first commit

core/modules/file/tests/file_module_test/file_module_test.info.yml

@@ -0,0 +1,10 @@
+name: 'File test'
+type: module
+description: 'Provides hooks for testing File module functionality.'
+package: Testing
+# version: VERSION
+
+# Information added by Drupal.org packaging script on 2024-07-04
+version: '10.3.1'
+project: 'drupal'
+datestamp: 1720094222

core/modules/file/tests/file_module_test/file_module_test.routing.yml

@@ -0,0 +1,10 @@
+file_module_test.managed_test:
+  path: '/file/test/{tree}/{extended}/{multiple}/{default_fids}'
+  defaults:
+    _form: '\Drupal\file_module_test\Form\FileModuleTestForm'
+    tree: TRUE
+    extended: TRUE
+    multiple: FALSE
+    default_fids: NULL
+  requirements:
+    _access: 'TRUE'

core/modules/file/tests/file_module_test/src/Form/FileModuleTestForm.php

@@ -0,0 +1,91 @@
+<?php
+
+namespace Drupal\file_module_test\Form;
+
+use Drupal\Core\Form\FormBase;
+use Drupal\Core\Form\FormStateInterface;
+
+/**
+ * Form controller for file_module_test module.
+ *
+ * @internal
+ */
+class FileModuleTestForm extends FormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'file_module_test_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   *
+   * @param array $form
+   *   An associative array containing the structure of the form.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
+   * @param bool $tree
+   *   (optional) If the form should use #tree. Defaults to TRUE.
+   * @param bool $extended
+   *   (optional) If the form should use #extended. Defaults to TRUE.
+   * @param bool $multiple
+   *   (optional) If the form should use #multiple. Defaults to FALSE.
+   * @param array $default_fids
+   *   (optional) Any default file IDs to use.
+   */
+  public function buildForm(array $form, FormStateInterface $form_state, $tree = TRUE, $extended = TRUE, $multiple = FALSE, $default_fids = NULL) {
+    $form['#tree'] = (bool) $tree;
+
+    $form['nested']['file'] = [
+      '#type' => 'managed_file',
+      '#title' => $this->t('Managed <em>@type</em>', ['@type' => 'file & butter']),
+      '#upload_location' => 'public://test',
+      '#progress_message' => $this->t('Processing...'),
+      '#extended' => (bool) $extended,
+      '#size' => 13,
+      '#multiple' => (bool) $multiple,
+    ];
+    if ($default_fids) {
+      $default_fids = explode(',', $default_fids);
+      $form['nested']['file']['#default_value'] = $extended ? ['fids' => $default_fids] : $default_fids;
+    }
+
+    $form['textfield'] = [
+      '#type' => 'textfield',
+      '#title' => $this->t('Type a value and ensure it stays'),
+    ];
+
+    $form['submit'] = [
+      '#type' => 'submit',
+      '#value' => $this->t('Save'),
+    ];
+
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {
+    if ($form['#tree']) {
+      $uploads = $form_state->getValue(['nested', 'file']);
+    }
+    else {
+      $uploads = $form_state->getValue('file');
+    }
+
+    if ($form['nested']['file']['#extended']) {
+      $uploads = $uploads['fids'];
+    }
+
+    $fids = [];
+    foreach ($uploads as $fid) {
+      $fids[] = $fid;
+    }
+
+    \Drupal::messenger()->addStatus($this->t('The file ids are %fids.', ['%fids' => implode(',', $fids)]));
+  }
+
+}

core/modules/file/tests/file_test/file_test.info.yml

@@ -0,0 +1,10 @@
+name: 'File test'
+type: module
+description: 'Support module for file handling tests.'
+package: Testing
+# version: VERSION
+
+# Information added by Drupal.org packaging script on 2024-07-04
+version: '10.3.1'
+project: 'drupal'
+datestamp: 1720094222

core/modules/file/tests/file_test/file_test.module

@@ -0,0 +1,354 @@
+<?php
+
+/**
+ * @file
+ * Helper module for the file tests.
+ *
+ * The caller is must call file_test_reset() to initializing this module before
+ * calling file_test_get_calls() or file_test_set_return().
+ */
+
+use Drupal\file\Entity\File;
+
+const FILE_URL_TEST_CDN_1 = 'http://cdn1.example.com';
+const FILE_URL_TEST_CDN_2 = 'http://cdn2.example.com';
+
+/**
+ * Reset/initialize the history of calls to the file_* hooks.
+ *
+ * @see file_test_get_calls()
+ * @see file_test_reset()
+ */
+function file_test_reset() {
+  // Keep track of calls to these hooks
+  $results = [
+    'load' => [],
+    'validate' => [],
+    'download' => [],
+    'insert' => [],
+    'update' => [],
+    'copy' => [],
+    'move' => [],
+    'delete' => [],
+  ];
+  \Drupal::state()->set('file_test.results', $results);
+
+  // These hooks will return these values, see file_test_set_return().
+  $return = [
+    'validate' => [],
+    'download' => NULL,
+  ];
+  \Drupal::state()->set('file_test.return', $return);
+}
+
+/**
+ * Gets the arguments passed to a given hook invocation.
+ *
+ * Arguments are gathered since file_test_reset() was last called.
+ *
+ * @param string $op
+ *   One of the hook_file_* operations: 'load', 'validate', 'download',
+ *   'insert', 'update', 'copy', 'move', 'delete'.
+ *
+ * @return array
+ *   Array of the parameters passed to each call.
+ *
+ * @see _file_test_log_call()
+ * @see file_test_reset()
+ */
+function file_test_get_calls($op) {
+  $results = \Drupal::state()->get('file_test.results', []);
+  return $results[$op];
+}
+
+/**
+ * Get an array with the calls for all hooks.
+ *
+ * @return array
+ *   An array keyed by hook name ('load', 'validate', 'download', 'insert',
+ *   'update', 'copy', 'move', 'delete') with values being arrays of parameters
+ *   passed to each call.
+ */
+function file_test_get_all_calls() {
+  return \Drupal::state()->get('file_test.results', []);
+}
+
+/**
+ * Store the values passed to a hook invocation.
+ *
+ * @param string $op
+ *   One of the hook_file_* operations: 'load', 'validate', 'download',
+ *   'insert', 'update', 'copy', 'move', 'delete'.
+ * @param array $args
+ *   Values passed to hook.
+ *
+ * @see file_test_get_calls()
+ * @see file_test_reset()
+ */
+function _file_test_log_call($op, $args) {
+  if (\Drupal::state()->get('file_test.count_hook_invocations', TRUE)) {
+    $results = \Drupal::state()->get('file_test.results', []);
+    $results[$op][] = $args;
+    \Drupal::state()->set('file_test.results', $results);
+  }
+}
+
+/**
+ * Load the appropriate return value.
+ *
+ * @param string $op
+ *   One of the hook_file_[validate,download] operations.
+ *
+ * @return mixed
+ *   Value set by file_test_set_return().
+ *
+ * @see file_test_set_return()
+ * @see file_test_reset()
+ */
+function _file_test_get_return($op) {
+  $return = \Drupal::state()->get('file_test.return', [$op => NULL]);
+  return $return[$op];
+}
+
+/**
+ * Assign a return value for a given operation.
+ *
+ * @param string $op
+ *   One of the hook_file_[validate,download] operations.
+ * @param mixed $value
+ *   Value for the hook to return.
+ *
+ * @see _file_test_get_return()
+ * @see file_test_reset()
+ */
+function file_test_set_return($op, $value) {
+  $return = \Drupal::state()->get('file_test.return', []);
+  $return[$op] = $value;
+  \Drupal::state()->set('file_test.return', $return);
+}
+
+/**
+ * Implements hook_ENTITY_TYPE_load() for file entities.
+ */
+function file_test_file_load($files) {
+  foreach ($files as $file) {
+    _file_test_log_call('load', [$file->id()]);
+    // Assign a value on the object so that we can test that the $file is passed
+    // by reference.
+    $file->file_test['loaded'] = TRUE;
+  }
+}
+
+/**
+ * Implements hook_file_download().
+ */
+function file_test_file_download($uri) {
+  if (\Drupal::state()->get('file_test.allow_all', FALSE)) {
+    $files = \Drupal::entityTypeManager()->getStorage('file')->loadByProperties(['uri' => $uri]);
+    $file = reset($files);
+    return file_get_content_headers($file);
+  }
+  _file_test_log_call('download', [$uri]);
+  return _file_test_get_return('download');
+}
+
+/**
+ * Implements hook_ENTITY_TYPE_insert() for file entities.
+ */
+function file_test_file_insert(File $file) {
+  _file_test_log_call('insert', [$file->id()]);
+}
+
+/**
+ * Implements hook_ENTITY_TYPE_update() for file entities.
+ */
+function file_test_file_update(File $file) {
+  _file_test_log_call('update', [$file->id()]);
+}
+
+/**
+ * Implements hook_file_copy().
+ */
+function file_test_file_copy(File $file, $source) {
+  _file_test_log_call('copy', [$file->id(), $source->id()]);
+}
+
+/**
+ * Implements hook_file_move().
+ */
+function file_test_file_move(File $file, File $source) {
+  _file_test_log_call('move', [$file->id(), $source->id()]);
+}
+
+/**
+ * Implements hook_ENTITY_TYPE_predelete() for file entities.
+ */
+function file_test_file_predelete(File $file) {
+  _file_test_log_call('delete', [$file->id()]);
+}
+
+/**
+ * Implements hook_file_url_alter().
+ */
+function file_test_file_url_alter(&$uri) {
+  /** @var \Drupal\Core\StreamWrapper\StreamWrapperManagerInterface $stream_wrapper_manager */
+  $stream_wrapper_manager = \Drupal::service('stream_wrapper_manager');
+
+  // Only run this hook when this variable is set. Otherwise, we'd have to add
+  // another hidden test module just for this hook.
+  $alter_mode = \Drupal::state()->get('file_test.hook_file_url_alter');
+  if (!$alter_mode) {
+    return;
+  }
+  // Test alteration of file URLs to use a CDN.
+  elseif ($alter_mode == 'cdn') {
+    $cdn_extensions = ['css', 'js', 'gif', 'jpg', 'jpeg', 'png'];
+
+    // Most CDNs don't support private file transfers without a lot of hassle,
+    // so don't support this in the common case.
+    $schemes = ['public'];
+
+    $scheme = $stream_wrapper_manager::getScheme($uri);
+
+    // Only serve shipped files and public created files from the CDN.
+    if (!$scheme || in_array($scheme, $schemes)) {
+      // Shipped files.
+      if (!$scheme) {
+        $path = $uri;
+      }
+      // Public created files.
+      else {
+        $wrapper = $stream_wrapper_manager->getViaScheme($scheme);
+        $path = $wrapper->getDirectoryPath() . '/' . $stream_wrapper_manager::getTarget($uri);
+      }
+
+      // Clean up Windows paths.
+      $path = str_replace('\\', '/', $path);
+
+      // Serve files with one of the CDN extensions from CDN 1, all others from
+      // CDN 2.
+      $pathinfo = pathinfo($path);
+      if (array_key_exists('extension', $pathinfo) && in_array($pathinfo['extension'], $cdn_extensions)) {
+        $uri = FILE_URL_TEST_CDN_1 . '/' . $path;
+      }
+      else {
+        $uri = FILE_URL_TEST_CDN_2 . '/' . $path;
+      }
+    }
+  }
+  // Test alteration of file URLs to use root-relative URLs.
+  elseif ($alter_mode == 'root-relative') {
+    // Only serve shipped files and public created files with root-relative
+    // URLs.
+    $scheme = $stream_wrapper_manager::getScheme($uri);
+    if (!$scheme || $scheme == 'public') {
+      // Shipped files.
+      if (!$scheme) {
+        $path = $uri;
+      }
+      // Public created files.
+      else {
+        $wrapper = $stream_wrapper_manager->getViaScheme($scheme);
+        $path = $wrapper->getDirectoryPath() . '/' . $stream_wrapper_manager::getTarget($uri);
+      }
+
+      // Clean up Windows paths.
+      $path = str_replace('\\', '/', $path);
+
+      // Generate a root-relative URL.
+      $uri = base_path() . '/' . $path;
+    }
+  }
+  // Test alteration of file URLs to use protocol-relative URLs.
+  elseif ($alter_mode == 'protocol-relative') {
+    // Only serve shipped files and public created files with protocol-relative
+    // URLs.
+    $scheme = $stream_wrapper_manager::getScheme($uri);
+    if (!$scheme || $scheme == 'public') {
+      // Shipped files.
+      if (!$scheme) {
+        $path = $uri;
+      }
+      // Public created files.
+      else {
+        $wrapper = $stream_wrapper_manager->getViaScheme($scheme);
+        $path = $wrapper->getDirectoryPath() . '/' . $stream_wrapper_manager::getTarget($uri);
+      }
+
+      // Clean up Windows paths.
+      $path = str_replace('\\', '/', $path);
+
+      // Generate a protocol-relative URL.
+      $uri = '/' . base_path() . '/' . $path;
+    }
+  }
+}
+
+/**
+ * Implements hook_file_mimetype_mapping_alter().
+ */
+function file_test_file_mimetype_mapping_alter(&$mapping) {
+  // Add new mappings.
+  $mapping['mimetypes']['file_test_mimetype_1'] = 'made_up/file_test_1';
+  $mapping['mimetypes']['file_test_mimetype_2'] = 'made_up/file_test_2';
+  $mapping['mimetypes']['file_test_mimetype_3'] = 'made_up/doc';
+  $mapping['extensions']['file_test_1'] = 'file_test_mimetype_1';
+  $mapping['extensions']['file_test_2'] = 'file_test_mimetype_2';
+  $mapping['extensions']['file_test_3'] = 'file_test_mimetype_2';
+  // Override existing mapping.
+  $mapping['extensions']['doc'] = 'file_test_mimetype_3';
+}
+
+/**
+ * Helper validator that returns the $errors parameter.
+ */
+function file_test_validator(File $file, $errors) {
+  return $errors;
+}
+
+/**
+ * Helper function for testing FileSystemInterface::scanDirectory().
+ *
+ * Each time the function is called the file is stored in a static variable.
+ * When the function is called with no $filepath parameter, the results are
+ * returned.
+ *
+ * @param string|null $filepath
+ *   File path
+ * @param bool $reset
+ *   (optional) If to reset the internal memory cache. If TRUE is passed, the
+ *   first parameter has no effect. Defaults to FALSE.
+ *
+ * @return array
+ *   If $filepath is NULL, an array of all previous $filepath parameters
+ */
+function file_test_file_scan_callback($filepath = NULL, $reset = FALSE) {
+  static $files = [];
+
+  if ($reset) {
+    $files = [];
+  }
+  elseif ($filepath) {
+    $files[] = $filepath;
+  }
+
+  return $files;
+}
+
+/**
+ * Reset static variables used by file_test_file_scan_callback().
+ */
+function file_test_file_scan_callback_reset() {
+  file_test_file_scan_callback(NULL, TRUE);
+}
+
+/**
+ * Implements hook_entity_info_alter().
+ */
+function file_test_entity_type_alter(&$entity_types) {
+  if (\Drupal::state()->get('file_test_alternate_access_handler', FALSE)) {
+    /** @var \Drupal\Core\Entity\EntityTypeInterface[] $entity_types */
+    $entity_types['file']
+      ->setAccessClass('Drupal\file_test\FileTestAccessControlHandler');
+  }
+}

core/modules/file/tests/file_test/file_test.routing.yml

@@ -0,0 +1,18 @@
+file.test:
+  path: '/file-test/upload'
+  defaults:
+    _form: '\Drupal\file_test\Form\FileTestForm'
+  requirements:
+    _access: 'TRUE'
+file.save_upload_from_form_test:
+  path: '/file-test/save_upload_from_form_test'
+  defaults:
+    _form: '\Drupal\file_test\Form\FileTestSaveUploadFromForm'
+  requirements:
+    _access: 'TRUE'
+file.required_test:
+  path: '/file-test/upload_required'
+  defaults:
+    _form: '\Drupal\file_test\Form\FileRequiredTestForm'
+  requirements:
+    _access: 'TRUE'

core/modules/file/tests/file_test/file_test.services.yml

@@ -0,0 +1,22 @@
+services:
+  stream_wrapper.dummy_readonly:
+    class: Drupal\file_test\StreamWrapper\DummyReadOnlyStreamWrapper
+    tags:
+      - { name: stream_wrapper, scheme: dummy-readonly }
+  stream_wrapper.dummy_remote:
+    class: Drupal\file_test\StreamWrapper\DummyRemoteStreamWrapper
+    tags:
+      - { name: stream_wrapper, scheme: dummy-remote }
+  stream_wrapper.dummy:
+    class: Drupal\file_test\StreamWrapper\DummyStreamWrapper
+    tags:
+      - { name: stream_wrapper, scheme: dummy }
+  stream_wrapper.dummy_external_readonly:
+    class: Drupal\file_test\StreamWrapper\DummyExternalReadOnlyWrapper
+    tags:
+      - { name: stream_wrapper, scheme: dummy-external-readonly }
+  stream_wrapper.dummy_multiple:
+    class: Drupal\file_test\StreamWrapper\DummyMultipleStreamWrapper
+    tags:
+      - { name: stream_wrapper, scheme: dummy1 }
+      - { name: stream_wrapper, scheme: dummy2 }

core/modules/file/tests/file_test/src/FileTestAccessControlHandler.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace Drupal\file_test;
+
+use Drupal\Core\Entity\EntityInterface;
+use Drupal\Core\Session\AccountInterface;
+use Drupal\file\FileAccessFormatterControlHandlerInterface;
+use Drupal\file\FileAccessControlHandler;
+
+/**
+ * Defines a class for an alternate file access control handler.
+ */
+class FileTestAccessControlHandler extends FileAccessControlHandler implements FileAccessFormatterControlHandlerInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function checkAccess(EntityInterface $entity, $operation, AccountInterface $account) {
+    \Drupal::state()->set('file_access_formatter_check', TRUE);
+    return parent::checkAccess($entity, $operation, $account);
+  }
+
+}

core/modules/file/tests/file_test/src/Form/FileRequiredTestForm.php

@@ -0,0 +1,28 @@
+<?php
+
+namespace Drupal\file_test\Form;
+
+use Drupal\Core\Form\FormStateInterface;
+
+/**
+ * File required test form class.
+ */
+class FileRequiredTestForm extends FileTestForm {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return '_file_required_test_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+    $form = parent::buildForm($form, $form_state);
+    $form['file_test_upload']['#required'] = TRUE;
+    return $form;
+  }
+
+}

core/modules/file/tests/file_test/src/Form/FileTestForm.php

@@ -0,0 +1,144 @@
+<?php
+
+namespace Drupal\file_test\Form;
+
+use Drupal\Core\File\FileExists;
+use Drupal\Core\File\FileSystemInterface;
+use Drupal\Core\Form\FormInterface;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\StringTranslation\TranslatableMarkup;
+
+/**
+ * File test form class.
+ */
+class FileTestForm implements FormInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return '_file_test_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+    $form['file_test_upload'] = [
+      '#type' => 'file',
+      '#title' => t('Upload a file'),
+    ];
+    $form['file_test_replace'] = [
+      '#type' => 'select',
+      '#title' => t('Replace existing image'),
+      '#options' => [
+        FileExists::Rename->name => new TranslatableMarkup('Appends number until name is unique'),
+        FileExists::Replace->name => new TranslatableMarkup('Replace the existing file'),
+        FileExists::Error->name => new TranslatableMarkup('Fail with an error'),
+      ],
+      '#default_value' => FileExists::Rename->name,
+    ];
+    $form['file_subdir'] = [
+      '#type' => 'textfield',
+      '#title' => t('Subdirectory for test file'),
+      '#default_value' => '',
+    ];
+
+    $form['extensions'] = [
+      '#type' => 'textfield',
+      '#title' => t('Allowed extensions.'),
+      '#default_value' => '',
+    ];
+
+    $form['allow_all_extensions'] = [
+      '#title' => t('Allow all extensions?'),
+      '#type' => 'radios',
+      '#options' => [
+        'false' => 'No',
+        'empty_array' => 'Empty array',
+        'empty_string' => 'Empty string',
+      ],
+      '#default_value' => 'false',
+    ];
+
+    $form['is_image_file'] = [
+      '#type' => 'checkbox',
+      '#title' => t('Is this an image file?'),
+      '#default_value' => TRUE,
+    ];
+
+    $form['submit'] = [
+      '#type' => 'submit',
+      '#value' => t('Submit'),
+    ];
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validateForm(array &$form, FormStateInterface $form_state) {}
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {
+    // Process the upload and perform validation. Note: we're using the
+    // form value for the $replace parameter.
+    if (!$form_state->isValueEmpty('file_subdir')) {
+      $destination = 'temporary://' . $form_state->getValue('file_subdir');
+      \Drupal::service('file_system')->prepareDirectory($destination, FileSystemInterface::CREATE_DIRECTORY);
+    }
+    else {
+      $destination = FALSE;
+    }
+
+    // Setup validators.
+    $validators = [];
+    if ($form_state->getValue('is_image_file')) {
+      $validators['FileIsImage'] = [];
+    }
+
+    $allow = $form_state->getValue('allow_all_extensions');
+    if ($allow === 'empty_array') {
+      $validators['FileExtension'] = [];
+    }
+    elseif ($allow === 'empty_string') {
+      $validators['FileExtension'] = ['extensions' => ''];
+    }
+    elseif (!$form_state->isValueEmpty('extensions')) {
+      $validators['FileExtension'] = ['extensions' => $form_state->getValue('extensions')];
+    }
+
+    // The test for \Drupal::service('file_system')->moveUploadedFile()
+    // triggering a warning is unavoidable. We're interested in what happens
+    // afterwards in file_save_upload().
+    if (\Drupal::state()->get('file_test.disable_error_collection')) {
+      define('SIMPLETEST_COLLECT_ERRORS', FALSE);
+    }
+
+    $file = file_save_upload('file_test_upload', $validators, $destination, 0, static::fileExistsFromName($form_state->getValue('file_test_replace')));
+    if ($file) {
+      $form_state->setValue('file_test_upload', $file);
+      \Drupal::messenger()->addStatus(t('File @filepath was uploaded.', ['@filepath' => $file->getFileUri()]));
+      \Drupal::messenger()->addStatus(t('File name is @filename.', ['@filename' => $file->getFilename()]));
+      \Drupal::messenger()->addStatus(t('File MIME type is @mimetype.', ['@mimetype' => $file->getMimeType()]));
+      \Drupal::messenger()->addStatus(t('You WIN!'));
+    }
+    elseif ($file === FALSE) {
+      \Drupal::messenger()->addError(t('Epic upload FAIL!'));
+    }
+  }
+
+  /**
+   * Get a FileExists enum from its name.
+   */
+  protected static function fileExistsFromName(string $name): FileExists {
+    return match ($name) {
+      FileExists::Replace->name => FileExists::Replace,
+      FileExists::Error->name => FileExists::Error,
+      default => FileExists::Rename,
+    };
+  }
+
+}

core/modules/file/tests/file_test/src/Form/FileTestSaveUploadFromForm.php

@@ -0,0 +1,202 @@
+<?php
+
+namespace Drupal\file_test\Form;
+
+use Drupal\Core\File\FileExists;
+use Drupal\Core\File\FileSystemInterface;
+use Drupal\Core\Form\FormBase;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Messenger\MessengerInterface;
+use Drupal\Core\State\StateInterface;
+use Drupal\Core\StringTranslation\TranslatableMarkup;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * File test form class.
+ */
+class FileTestSaveUploadFromForm extends FormBase {
+
+  /**
+   * Stores the state storage service.
+   *
+   * @var \Drupal\Core\State\StateInterface
+   */
+  protected $state;
+
+  /**
+   * The messenger.
+   *
+   * @var \Drupal\Core\Messenger\MessengerInterface
+   */
+  protected $messenger;
+
+  /**
+   * Constructs a FileTestSaveUploadFromForm object.
+   *
+   * @param \Drupal\Core\State\StateInterface $state
+   *   The state key value store.
+   * @param \Drupal\Core\Messenger\MessengerInterface $messenger
+   *   The messenger.
+   */
+  public function __construct(StateInterface $state, MessengerInterface $messenger) {
+    $this->state = $state;
+    $this->messenger = $messenger;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    return new static(
+      $container->get('state'),
+      $container->get('messenger')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return '_file_test_save_upload_from_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+    $form['file_test_upload'] = [
+      '#type' => 'file',
+      '#multiple' => TRUE,
+      '#title' => $this->t('Upload a file'),
+    ];
+    $form['file_test_replace'] = [
+      '#type' => 'select',
+      '#title' => $this->t('Replace existing image'),
+      '#options' => [
+        FileExists::Rename->name => new TranslatableMarkup('Appends number until name is unique'),
+        FileExists::Replace->name => new TranslatableMarkup('Replace the existing file'),
+        FileExists::Error->name => new TranslatableMarkup('Fail with an error'),
+      ],
+      '#default_value' => FileExists::Rename->name,
+    ];
+    $form['file_subdir'] = [
+      '#type' => 'textfield',
+      '#title' => $this->t('Subdirectory for test file'),
+      '#default_value' => '',
+    ];
+
+    $form['extensions'] = [
+      '#type' => 'textfield',
+      '#title' => $this->t('Allowed extensions.'),
+      '#default_value' => '',
+    ];
+
+    $form['allow_all_extensions'] = [
+      '#title' => t('Allow all extensions?'),
+      '#type' => 'radios',
+      '#options' => [
+        'false' => 'No',
+        'empty_array' => 'Empty array',
+        'empty_string' => 'Empty string',
+      ],
+      '#default_value' => 'false',
+    ];
+
+    $form['is_image_file'] = [
+      '#type' => 'checkbox',
+      '#title' => $this->t('Is this an image file?'),
+      '#default_value' => TRUE,
+    ];
+
+    $form['error_message'] = [
+      '#type' => 'textfield',
+      '#title' => $this->t('Custom error message.'),
+      '#default_value' => '',
+    ];
+
+    $form['submit'] = [
+      '#type' => 'submit',
+      '#value' => $this->t('Submit'),
+    ];
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validateForm(array &$form, FormStateInterface $form_state) {
+    // Process the upload and perform validation. Note: we're using the
+    // form value for the $replace parameter.
+    if (!$form_state->isValueEmpty('file_subdir')) {
+      $destination = 'temporary://' . $form_state->getValue('file_subdir');
+      \Drupal::service('file_system')->prepareDirectory($destination, FileSystemInterface::CREATE_DIRECTORY);
+    }
+    else {
+      $destination = FALSE;
+    }
+
+    // Preset custom error message if requested.
+    if ($form_state->getValue('error_message')) {
+      $this->messenger->addError($form_state->getValue('error_message'));
+    }
+
+    // Setup validators.
+    $validators = [];
+    if ($form_state->getValue('is_image_file')) {
+      $validators['FileIsImage'] = [];
+    }
+
+    $allow = $form_state->getValue('allow_all_extensions');
+    if ($allow === 'empty_array') {
+      $validators['FileExtension'] = [];
+    }
+    elseif ($allow === 'empty_string') {
+      $validators['FileExtension'] = ['extensions' => ''];
+    }
+    elseif (!$form_state->isValueEmpty('extensions')) {
+      $validators['FileExtension'] = ['extensions' => $form_state->getValue('extensions')];
+    }
+
+    // The test for \Drupal::service('file_system')->moveUploadedFile()
+    // triggering a warning is unavoidable. We're interested in what happens
+    // afterwards in _file_save_upload_from_form().
+    if ($this->state->get('file_test.disable_error_collection')) {
+      define('SIMPLETEST_COLLECT_ERRORS', FALSE);
+    }
+
+    $form['file_test_upload']['#upload_validators'] = $validators;
+    $form['file_test_upload']['#upload_location'] = $destination;
+
+    $this->messenger->addStatus($this->t('Number of error messages before _file_save_upload_from_form(): @count.', ['@count' => count($this->messenger->messagesByType(MessengerInterface::TYPE_ERROR))]));
+    $file = _file_save_upload_from_form($form['file_test_upload'], $form_state, 0, static::fileExistsFromName($form_state->getValue('file_test_replace')));
+    $this->messenger->addStatus($this->t('Number of error messages after _file_save_upload_from_form(): @count.', ['@count' => count($this->messenger->messagesByType(MessengerInterface::TYPE_ERROR))]));
+
+    if ($file) {
+      $form_state->setValue('file_test_upload', $file);
+      $this->messenger->addStatus($this->t('File @filepath was uploaded.', ['@filepath' => $file->getFileUri()]));
+      $this->messenger->addStatus($this->t('File name is @filename.', ['@filename' => $file->getFilename()]));
+      $this->messenger->addStatus($this->t('File MIME type is @mimetype.', ['@mimetype' => $file->getMimeType()]));
+      $this->messenger->addStatus($this->t('You WIN!'));
+    }
+    elseif ($file === FALSE) {
+      $this->messenger->addError($this->t('Epic upload FAIL!'));
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {}
+
+  /**
+   * Get a FileExists enum from its name.
+   */
+  protected static function fileExistsFromName(string $name): FileExists {
+    return match ($name) {
+      FileExists::Replace->name => FileExists::Replace,
+      FileExists::Error->name => FileExists::Error,
+      default => FileExists::Rename,
+    };
+  }
+
+}

core/modules/file/tests/file_test/src/StreamWrapper/DummyExternalReadOnlyWrapper.php

@@ -0,0 +1,149 @@
+<?php
+
+namespace Drupal\file_test\StreamWrapper;
+
+use Drupal\Core\StreamWrapper\ReadOnlyStream;
+use Drupal\Core\StreamWrapper\StreamWrapperInterface;
+
+/**
+ * Helper class for testing the stream wrapper registry.
+ *
+ * Dummy external stream wrapper implementation (dummy-external-readonly://).
+ */
+class DummyExternalReadOnlyWrapper extends ReadOnlyStream {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getType() {
+    return StreamWrapperInterface::READ_VISIBLE;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getName() {
+    return t('Dummy external stream wrapper (readonly)');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDescription() {
+    return t('Dummy external read-only stream wrapper for testing.');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getExternalUrl() {
+    [, $target] = explode('://', $this->uri, 2);
+    return 'https://www.dummy-external-readonly.com/' . $target;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function realpath() {
+    return FALSE;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function dirname($uri = NULL) {
+    return FALSE;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function dir_closedir() {
+    return FALSE;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function dir_opendir($path, $options) {
+    return FALSE;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function dir_readdir() {
+    return FALSE;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function dir_rewinddir() {
+    return FALSE;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function stream_cast($cast_as) {
+    return FALSE;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function stream_close() {
+    return FALSE;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function stream_eof() {
+    return FALSE;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function stream_read($count) {
+    return FALSE;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function stream_seek($offset, $whence = SEEK_SET) {
+    return FALSE;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function stream_set_option($option, $arg1, $arg2) {
+    return FALSE;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function stream_stat() {
+    return FALSE;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function stream_tell() {
+    return FALSE;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function url_stat($path, $flags) {
+    return FALSE;
+  }
+
+}

core/modules/file/tests/file_test/src/StreamWrapper/DummyMultipleStreamWrapper.php

@@ -0,0 +1,10 @@
+<?php
+
+namespace Drupal\file_test\StreamWrapper;
+
+/**
+ * Helper class for testing the stream wrapper registry.
+ *
+ * Dummy stream wrapper implementation (dummy1://, dummy2://).
+ */
+class DummyMultipleStreamWrapper extends DummyStreamWrapper {}

core/modules/file/tests/file_test/src/StreamWrapper/DummyReadOnlyStreamWrapper.php

@@ -0,0 +1,50 @@
+<?php
+
+namespace Drupal\file_test\StreamWrapper;
+
+use Drupal\Core\StreamWrapper\LocalReadOnlyStream;
+
+/**
+ * Helper class for testing the stream wrapper registry.
+ *
+ * Dummy stream wrapper implementation (dummy-readonly://).
+ */
+class DummyReadOnlyStreamWrapper extends LocalReadOnlyStream {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getName() {
+    return t('Dummy files (readonly)');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDescription() {
+    return t('Dummy wrapper for testing (readonly).');
+  }
+
+  public function getDirectoryPath() {
+    return \Drupal::getContainer()->getParameter('site.path') . '/files';
+  }
+
+  /**
+   * Override getInternalUri().
+   *
+   * Return a dummy path for testing.
+   */
+  public function getInternalUri() {
+    return '/dummy/example.txt';
+  }
+
+  /**
+   * Override getExternalUrl().
+   *
+   * Return the HTML URI of a public file.
+   */
+  public function getExternalUrl() {
+    return '/dummy/example.txt';
+  }
+
+}

core/modules/file/tests/file_test/src/StreamWrapper/DummyRemoteReadOnlyStreamWrapper.php

@@ -0,0 +1,33 @@
+<?php
+
+namespace Drupal\file_test\StreamWrapper;
+
+use Drupal\Core\StreamWrapper\StreamWrapperInterface;
+
+/**
+ * Dummy read-only remote stream wrapper (dummy-remote-readonly://).
+ */
+class DummyRemoteReadOnlyStreamWrapper extends DummyRemoteStreamWrapper {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getType() {
+    return StreamWrapperInterface::READ_VISIBLE;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getName() {
+    return t('Dummy remote read-only files');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDescription() {
+    return t('Dummy remote read-only stream wrapper for testing.');
+  }
+
+}

core/modules/file/tests/file_test/src/StreamWrapper/DummyRemoteStreamWrapper.php

@@ -0,0 +1,34 @@
+<?php
+
+namespace Drupal\file_test\StreamWrapper;
+
+use Drupal\Core\StreamWrapper\PublicStream;
+
+/**
+ * Helper class for testing the stream wrapper registry.
+ *
+ * Dummy remote stream wrapper implementation (dummy-remote://).
+ *
+ * Basically just the public scheme but not returning a local file for realpath.
+ */
+class DummyRemoteStreamWrapper extends PublicStream {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getName() {
+    return t('Dummy files (remote)');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDescription() {
+    return t('Dummy wrapper for testing (remote).');
+  }
+
+  public function realpath() {
+    return FALSE;
+  }
+
+}

core/modules/file/tests/file_test/src/StreamWrapper/DummyStreamWrapper.php

@@ -0,0 +1,50 @@
+<?php
+
+namespace Drupal\file_test\StreamWrapper;
+
+use Drupal\Core\StreamWrapper\LocalStream;
+
+/**
+ * Helper class for testing the stream wrapper registry.
+ *
+ * Dummy stream wrapper implementation (dummy://).
+ */
+class DummyStreamWrapper extends LocalStream {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getName() {
+    return t('Dummy files');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDescription() {
+    return t('Dummy wrapper for testing.');
+  }
+
+  public function getDirectoryPath() {
+    return \Drupal::getContainer()->getParameter('site.path') . '/files';
+  }
+
+  /**
+   * Override getInternalUri().
+   *
+   * Return a dummy path for testing.
+   */
+  public function getInternalUri() {
+    return '/dummy/example.txt';
+  }
+
+  /**
+   * Override getExternalUrl().
+   *
+   * Return the HTML URI of a public file.
+   */
+  public function getExternalUrl() {
+    return '/dummy/example.txt';
+  }
+
+}

core/modules/file/tests/modules/file_test_get_ids/file_test_get_ids.info.yml

@@ -0,0 +1,12 @@
+name: 'File test getIds'
+type: module
+description: 'Provides file source plugin restricted to used files.'
+package: Testing
+# version: VERSION
+dependencies:
+  - drupal:file
+
+# Information added by Drupal.org packaging script on 2024-07-04
+version: '10.3.1'
+project: 'drupal'
+datestamp: 1720094222

core/modules/file/tests/modules/file_test_get_ids/migrations/d7_file_used.yml

@@ -0,0 +1,33 @@
+id: d7_file_used
+migration_tags:
+  - Drupal 7
+  - Content
+source:
+  plugin: d7_file_used
+  scheme: public
+  constants:
+    source_base_path: ''
+process:
+  fid: fid
+  filename: filename
+  source_full_path:
+    -
+      plugin: concat
+      delimiter: /
+      source:
+        - constants/source_base_path
+        - filepath
+    -
+      plugin: urlencode
+  uri:
+    plugin: file_copy
+    source:
+      - '@source_full_path'
+      - uri
+  filemime: filemime
+  status: status
+  created: timestamp
+  changed: timestamp
+  uid: uid
+destination:
+  plugin: entity:file

core/modules/file/tests/modules/file_test_get_ids/src/Plugin/migrate/source/d7/FileUsed.php

@@ -0,0 +1,29 @@
+<?php
+
+namespace Drupal\file_test_get_ids\Plugin\migrate\source\d7;
+
+use Drupal\file\Plugin\migrate\source\d7\File;
+
+/**
+ * Drupal 7 file source from database restricted to used files.
+ *
+ * @MigrateSource(
+ *   id = "d7_file_used",
+ *   source_module = "file"
+ * )
+ */
+class FileUsed extends File {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function query() {
+    $query = parent::query();
+
+    // Join on file_usage table to only migrate used files.
+    $query->innerJoin('file_usage', 'fu', 'f.fid = fu.fid');
+
+    return $query;
+  }
+
+}

core/modules/file/tests/modules/file_test_views/file_test_views.info.yml

@@ -0,0 +1,13 @@
+name: 'File test views'
+type: module
+description: 'Provides default views for views file tests.'
+package: Testing
+# version: VERSION
+dependencies:
+  - drupal:file
+  - drupal:views
+
+# Information added by Drupal.org packaging script on 2024-07-04
+version: '10.3.1'
+project: 'drupal'
+datestamp: 1720094222

core/modules/file/tests/modules/file_test_views/test_views/views.view.file_extension_view.yml

@@ -0,0 +1,47 @@
+langcode: en
+status: true
+dependencies: {  }
+id: file_extension_view
+label: 'Test view for file extension views field handler'
+module: views
+description: ''
+tag: ''
+base_table: file_managed
+base_field: fid
+display:
+  default:
+    display_options:
+      defaults:
+        fields: false
+        pager: false
+        sorts: false
+      fields:
+        fid:
+          field: fid
+          id: fid
+          relationship: none
+          table: file_managed
+          plugin_id: field
+        extension:
+          field: extension
+          id: extension
+          relationship: none
+          table: file_managed
+          plugin_id: field
+          type: file_extension
+      pager:
+        options:
+          offset: 0
+        type: none
+      sorts:
+        fid:
+          field: fid
+          id: fid
+          order: ASC
+          relationship: none
+          table: file_managed
+          plugin_id: standard
+    display_plugin: default
+    display_title: Default
+    id: default
+    position: 0

core/modules/file/tests/modules/file_validator_test/file_validator_test.info.yml

@@ -0,0 +1,12 @@
+name: File validator test
+type: module
+description: Provides classes for file validator tests
+package: Testing
+# version: VERSION
+dependencies:
+  - drupal:file
+
+# Information added by Drupal.org packaging script on 2024-07-04
+version: '10.3.1'
+project: 'drupal'
+datestamp: 1720094222

core/modules/file/tests/modules/file_validator_test/file_validator_test.services.yml

@@ -0,0 +1,7 @@
+services:
+  _defaults:
+    autoconfigure: true
+  file_validation_test_subscriber:
+    class: Drupal\file_validator_test\EventSubscriber\FileValidationTestSubscriber
+  file_validation_sanitization_subscriber:
+    class: Drupal\file_validator_test\EventSubscriber\FileSanitizationEventSubscriber

core/modules/file/tests/modules/file_validator_test/src/EventSubscriber/FileSanitizationEventSubscriber.php

@@ -0,0 +1,44 @@
+<?php
+
+namespace Drupal\file_validator_test\EventSubscriber;
+
+use Drupal\Core\File\Event\FileUploadSanitizeNameEvent;
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+
+/**
+ * Provides a file sanitization listener for file upload tests.
+ */
+class FileSanitizationEventSubscriber implements EventSubscriberInterface {
+
+  /**
+   * The allowed extensions.
+   *
+   * @var string[]
+   */
+  protected array $allowedExtensions = [];
+
+  /**
+   * Handles the file sanitization event.
+   */
+  public function onFileSanitization(FileUploadSanitizeNameEvent $event) {
+    $this->allowedExtensions = $event->getAllowedExtensions();
+  }
+
+  /**
+   * Gets the allowed extensions.
+   *
+   * @return string[]
+   *   The allowed extensions.
+   */
+  public function getAllowedExtensions(): array {
+    return $this->allowedExtensions;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getSubscribedEvents(): array {
+    return [FileUploadSanitizeNameEvent::class => 'onFileSanitization'];
+  }
+
+}

core/modules/file/tests/modules/file_validator_test/src/EventSubscriber/FileValidationTestSubscriber.php

@@ -0,0 +1,32 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\file_validator_test\EventSubscriber;
+
+use Drupal\file\Validation\FileValidationEvent;
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+
+/**
+ * Provides a validation listener for file validation tests.
+ */
+class FileValidationTestSubscriber implements EventSubscriberInterface {
+
+  /**
+   * Handles the file validation event.
+   *
+   * @param \Drupal\file\Validation\FileValidationEvent $event
+   *   The event.
+   */
+  public function onFileValidation(FileValidationEvent $event): void {
+    _file_test_log_call('validate', [$event->file->id()]);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getSubscribedEvents(): array {
+    return [FileValidationEvent::class => 'onFileValidation'];
+  }
+
+}

core/modules/file/tests/src/Functional/DownloadTest.php

@@ -0,0 +1,224 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+use Drupal\Core\Database\Database;
+use Drupal\Core\File\FileSystemInterface;
+
+/**
+ * Tests for download/file transfer functions.
+ *
+ * @group file
+ */
+class DownloadTest extends FileManagedTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * The file URL generator.
+   *
+   * @var \Drupal\Core\File\FileUrlGeneratorInterface
+   */
+  protected $fileUrlGenerator;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+
+    // This test currently frequently causes the SQLite database to lock, so
+    // skip the test on SQLite until the issue can be resolved.
+    // @todo Fix root cause and re-enable in
+    //   https://www.drupal.org/project/drupal/issues/3311587
+    if (Database::getConnection()->driver() === 'sqlite') {
+      $this->markTestSkipped('Test frequently causes a locked database on SQLite');
+    }
+
+    $this->fileUrlGenerator = $this->container->get('file_url_generator');
+    // Clear out any hook calls.
+    file_test_reset();
+  }
+
+  /**
+   * Tests the public file transfer system.
+   */
+  public function testPublicFileTransfer(): void {
+    // Test generating a URL to a created file.
+    $file = $this->createFile();
+    $url = $this->fileUrlGenerator->generateAbsoluteString($file->getFileUri());
+    // URLs can't contain characters outside the ASCII set so $filename has to be
+    // encoded.
+    $filename = $GLOBALS['base_url'] . '/' . \Drupal::service('stream_wrapper_manager')->getViaScheme('public')->getDirectoryPath() . '/' . rawurlencode($file->getFilename());
+    $this->assertEquals($filename, $url, 'Correctly generated a URL for a created file.');
+    $http_client = $this->getHttpClient();
+    $response = $http_client->head($url);
+    $this->assertEquals(200, $response->getStatusCode(), 'Confirmed that the generated URL is correct by downloading the created file.');
+
+    // Test generating a URL to a shipped file (i.e. a file that is part of
+    // Drupal core, a module or a theme, for example a JavaScript file).
+    $filepath = 'core/assets/vendor/jquery/jquery.min.js';
+    $url = $this->fileUrlGenerator->generateAbsoluteString($filepath);
+    $this->assertEquals($GLOBALS['base_url'] . '/' . $filepath, $url, 'Correctly generated a URL for a shipped file.');
+    $response = $http_client->head($url);
+    $this->assertEquals(200, $response->getStatusCode(), 'Confirmed that the generated URL is correct by downloading the shipped file.');
+  }
+
+  /**
+   * Tests the private file transfer system.
+   */
+  public function testPrivateFileTransferWithoutPageCache(): void {
+    $this->doPrivateFileTransferTest();
+  }
+
+  /**
+   * Tests the private file transfer system.
+   */
+  protected function doPrivateFileTransferTest() {
+    // Set file downloads to private so handler functions get called.
+
+    // Create a file.
+    $contents = $this->randomMachineName(8);
+    $file = $this->createFile($contents . '.txt', $contents, 'private');
+    // Created private files without usage are by default not accessible
+    // for a user different from the owner, but createFile always uses uid 1
+    // as the owner of the files. Therefore make it permanent to allow access
+    // if a module allows it.
+    $file->setPermanent();
+    $file->save();
+
+    $url = $this->fileUrlGenerator->generateAbsoluteString($file->getFileUri());
+
+    // Set file_test access header to allow the download.
+    file_test_reset();
+    file_test_set_return('download', ['x-foo' => 'Bar']);
+    $this->drupalGet($url);
+    // Verify that header is set by file_test module on private download.
+    $this->assertSession()->responseHeaderEquals('x-foo', 'Bar');
+    // Verify that page cache is disabled on private file download.
+    $this->assertSession()->responseHeaderDoesNotExist('x-drupal-cache');
+    $this->assertSession()->statusCodeEquals(200);
+    // Ensure hook_file_download is fired correctly.
+    $this->assertEquals($file->getFileUri(), \Drupal::state()->get('file_test.results')['download'][0][0]);
+
+    // Test that the file transferred correctly.
+    $this->assertSame($contents, $this->getSession()->getPage()->getContent(), 'Contents of the file are correct.');
+    $http_client = $this->getHttpClient();
+
+    // Try non-existent file.
+    file_test_reset();
+    $not_found_url = $this->fileUrlGenerator->generateAbsoluteString('private://' . $this->randomMachineName() . '.txt');
+    $response = $http_client->head($not_found_url, ['http_errors' => FALSE]);
+    $this->assertSame(404, $response->getStatusCode(), 'Correctly returned 404 response for a non-existent file.');
+    // Assert that hook_file_download is not called.
+    $this->assertEquals([], \Drupal::state()->get('file_test.results')['download']);
+
+    // Having tried a non-existent file, try the original file again to ensure
+    // it's returned instead of a 404 response.
+    // Set file_test access header to allow the download.
+    file_test_reset();
+    file_test_set_return('download', ['x-foo' => 'Bar']);
+    $this->drupalGet($url);
+    // Verify that header is set by file_test module on private download.
+    $this->assertSession()->responseHeaderEquals('x-foo', 'Bar');
+    // Verify that page cache is disabled on private file download.
+    $this->assertSession()->responseHeaderDoesNotExist('x-drupal-cache');
+    $this->assertSession()->statusCodeEquals(200);
+    // Test that the file transferred correctly.
+    $this->assertSame($contents, $this->getSession()->getPage()->getContent(), 'Contents of the file are correct.');
+
+    // Deny access to all downloads via a -1 header.
+    file_test_set_return('download', -1);
+    $response = $http_client->head($url, ['http_errors' => FALSE]);
+    $this->assertSame(403, $response->getStatusCode(), 'Correctly denied access to a file when file_test sets the header to -1.');
+
+    // Try requesting the private file URL without a file specified.
+    file_test_reset();
+    $this->drupalGet('/system/files');
+    $this->assertSession()->statusCodeEquals(404);
+    // Assert that hook_file_download is not called.
+    $this->assertEquals([], \Drupal::state()->get('file_test.results')['download']);
+  }
+
+  /**
+   * Test FileUrlGeneratorInterface::generateString()
+   */
+  public function testFileCreateUrl(): void {
+    // "Special" ASCII characters.
+    $basename = " -._~!$'\"()*@[]?&+%#,;=:\n\x00" .
+      // Characters that look like a percent-escaped string.
+      "%23%25%26%2B%2F%3F" .
+      // Characters from various non-ASCII alphabets.
+      // cSpell:disable-next-line
+      "éøïвβ中國書۞";
+    $basename_encoded = '%20-._~%21%24%27%22%28%29%2A%40%5B%5D%3F%26%2B%25%23%2C%3B%3D%3A__' .
+      '%2523%2525%2526%252B%252F%253F' .
+      '%C3%A9%C3%B8%C3%AF%D0%B2%CE%B2%E4%B8%AD%E5%9C%8B%E6%9B%B8%DB%9E';
+
+    // Public files should not be served by Drupal, so their URLs should not be
+    // routed through Drupal, whereas private files should be served by Drupal,
+    // so they need to be. The difference is most apparent when $script_path
+    // is not empty (i.e., when not using clean URLs).
+    $clean_url_settings = [
+      'clean' => '',
+      'unclean' => 'index.php/',
+    ];
+    $public_directory_path = \Drupal::service('stream_wrapper_manager')->getViaScheme('public')->getDirectoryPath();
+    foreach ($clean_url_settings as $clean_url_setting => $script_path) {
+      $clean_urls = $clean_url_setting == 'clean';
+      $request = $this->prepareRequestForGenerator($clean_urls);
+      $base_path = $request->getSchemeAndHttpHost() . $request->getBasePath();
+      $this->checkUrl('public', '', $basename, $base_path . '/' . $public_directory_path . '/' . $basename_encoded);
+      $this->checkUrl('private', '', $basename, $base_path . '/' . $script_path . 'system/files/' . $basename_encoded);
+    }
+    $this->assertEquals('data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg==', $this->fileUrlGenerator->generateString('data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg==', FALSE));
+  }
+
+  /**
+   * Download a file from the URL generated by generateString().
+   *
+   * Create a file with the specified scheme, directory and filename; check that
+   * the URL generated by FileUrlGeneratorInterface::generateString() for the
+   * specified file equals the specified URL; fetch the URL and then compare the
+   * contents to the file.
+   *
+   * @param string $scheme
+   *   A scheme, e.g. "public".
+   * @param string $directory
+   *   A directory, possibly "".
+   * @param string $filename
+   *   A filename.
+   * @param string $expected_url
+   *   The expected URL.
+   */
+  private function checkUrl($scheme, $directory, $filename, $expected_url) {
+    // Convert $filename to a valid filename, i.e. strip characters not
+    // supported by the filesystem, and create the file in the specified
+    // directory.
+    $filepath = \Drupal::service('file_system')->createFilename($filename, $directory);
+    $directory_uri = $scheme . '://' . dirname($filepath);
+    \Drupal::service('file_system')->prepareDirectory($directory_uri, FileSystemInterface::CREATE_DIRECTORY);
+    $file = $this->createFile($filepath, NULL, $scheme);
+
+    $url = $this->fileUrlGenerator->generateAbsoluteString($file->getFileUri());
+    $this->assertEquals($expected_url, $url);
+
+    if ($scheme == 'private') {
+      // Tell the implementation of hook_file_download() in file_test.module
+      // that this file may be downloaded.
+      file_test_set_return('download', ['x-foo' => 'Bar']);
+    }
+
+    $this->drupalGet($url);
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->responseContains(file_get_contents($file->getFileUri()));
+
+    $file->delete();
+  }
+
+}

core/modules/file/tests/src/Functional/FileAddPermissionsUpdateTest.php

@@ -0,0 +1,56 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+use Drupal\FunctionalTests\Update\UpdatePathTestBase;
+use Drupal\user\Entity\Role;
+
+/**
+ * Tests file_post_update_add_permissions_to_roles().
+ *
+ * @group file
+ * @group legacy
+ *
+ * @see file_post_update_add_permissions_to_roles()
+ */
+class FileAddPermissionsUpdateTest extends UpdatePathTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setDatabaseDumpFiles(): void {
+    $this->databaseDumpFiles = [
+      __DIR__ . '/../../../../system/tests/fixtures/update/drupal-9.4.0.filled.standard.php.gz',
+    ];
+  }
+
+  /**
+   * Tests adding 'delete own files' permission.
+   */
+  public function testUpdate(): void {
+    $roles = Role::loadMultiple();
+    $this->assertGreaterThan(2, count($roles));
+    foreach ($roles as $role) {
+      $permissions = $role->toArray()['permissions'];
+      $this->assertNotContains('delete own files', $permissions);
+    }
+
+    $this->runUpdates();
+
+    $role = Role::load(Role::ANONYMOUS_ID);
+    $permissions = $role->toArray()['permissions'];
+    $this->assertNotContains('delete own files', $permissions);
+
+    $role = Role::load(Role::AUTHENTICATED_ID);
+    $permissions = $role->toArray()['permissions'];
+    $this->assertContains('delete own files', $permissions);
+
+    // Admin roles have the permission and do not need assigned.
+    $role = Role::load('administrator');
+    $permissions = $role->toArray()['permissions'];
+    $this->assertNotContains('delete own files', $permissions);
+  }
+
+}

core/modules/file/tests/src/Functional/FileFieldAnonymousSubmissionTest.php

@@ -0,0 +1,172 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+use Drupal\node\Entity\Node;
+use Drupal\user\RoleInterface;
+use Drupal\file\Entity\File;
+
+/**
+ * Confirm that file field submissions work correctly for anonymous visitors.
+ *
+ * @group file
+ */
+class FileFieldAnonymousSubmissionTest extends FileFieldTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    // Set up permissions for anonymous attacker user.
+    user_role_change_permissions(RoleInterface::ANONYMOUS_ID, [
+      'create article content' => TRUE,
+      'access content' => TRUE,
+    ]);
+  }
+
+  /**
+   * Tests the basic node submission for an anonymous visitor.
+   */
+  public function testAnonymousNode(): void {
+    $type = 'Article';
+    $title = 'test page';
+
+    // Load the node form.
+    $this->drupalLogout();
+    $this->drupalGet('node/add/article');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains("Create $type");
+
+    $edit = [
+      'title[0][value]' => $title,
+      'body[0][value]' => 'Test article',
+    ];
+    $this->submitForm($edit, 'Save');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains("$type $title has been created.");
+    $matches = [];
+    if (preg_match('@node/(\d+)$@', $this->getUrl(), $matches)) {
+      $nid = end($matches);
+      $this->assertNotEquals(0, $nid, 'The node ID was extracted from the URL.');
+      $node = Node::load($nid);
+      $this->assertNotNull($node, 'The node was loaded successfully.');
+    }
+  }
+
+  /**
+   * Tests file submission for an anonymous visitor.
+   */
+  public function testAnonymousNodeWithFile(): void {
+    $type = 'Article';
+    $title = 'Test page';
+    $this->createFileField('field_image', 'node', 'article', [], ['file_extensions' => 'txt png']);
+
+    // Load the node form.
+    $this->drupalLogout();
+    $this->drupalGet('node/add/article');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains("Create $type");
+
+    // Generate an image file.
+    $image = $this->getTestFile('image');
+
+    // Submit the form.
+    $edit = [
+      'title[0][value]' => $title,
+      'body[0][value]' => 'Test article',
+      'files[field_image_0]' => $this->container->get('file_system')->realpath($image->getFileUri()),
+    ];
+    $this->submitForm($edit, 'Save');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains("$type $title has been created.");
+    $matches = [];
+    if (preg_match('@node/(\d+)$@', $this->getUrl(), $matches)) {
+      $nid = end($matches);
+      $this->assertNotEquals(0, $nid, 'The node ID was extracted from the URL.');
+      $node = Node::load($nid);
+      $this->assertNotNull($node, 'The node was loaded successfully.');
+      $this->assertFileExists(File::load($node->field_image->target_id)->getFileUri());
+    }
+  }
+
+  /**
+   * Tests file submission for an anonymous visitor with a missing node title.
+   */
+  public function testAnonymousNodeWithFileWithoutTitle(): void {
+    $this->drupalLogout();
+    $this->doTestNodeWithFileWithoutTitle();
+  }
+
+  /**
+   * Tests file submission for an authenticated user with a missing node title.
+   */
+  public function testAuthenticatedNodeWithFileWithoutTitle(): void {
+    $admin_user = $this->drupalCreateUser([
+      'bypass node access',
+      'access content overview',
+      'administer nodes',
+    ]);
+    $this->drupalLogin($admin_user);
+    $this->doTestNodeWithFileWithoutTitle();
+  }
+
+  /**
+   * Helper method to test file submissions with missing node titles.
+   */
+  protected function doTestNodeWithFileWithoutTitle() {
+    $type = 'Article';
+    $title = 'Test page';
+    $this->createFileField('field_image', 'node', 'article', [], ['file_extensions' => 'txt png']);
+
+    // Load the node form.
+    $this->drupalGet('node/add/article');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains("Create $type");
+
+    // Generate an image file.
+    $image = $this->getTestFile('image');
+
+    // Submit the form but exclude the title field.
+    $edit = [
+      'body[0][value]' => 'Test article',
+      'files[field_image_0]' => $this->container->get('file_system')->realpath($image->getFileUri()),
+    ];
+    if (!$this->loggedInUser) {
+      $label = 'Save';
+    }
+    else {
+      $label = 'Save';
+    }
+    $this->submitForm($edit, $label);
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextNotContains("$type $title has been created.");
+    $this->assertSession()->pageTextContains('Title field is required.');
+
+    // Submit the form again but this time with the missing title field. This
+    // should still work.
+    $edit = [
+      'title[0][value]' => $title,
+    ];
+    $this->submitForm($edit, $label);
+
+    // Confirm the final submission actually worked.
+    $this->assertSession()->pageTextContains("$type $title has been created.");
+    $matches = [];
+    if (preg_match('@node/(\d+)$@', $this->getUrl(), $matches)) {
+      $nid = end($matches);
+      $this->assertNotEquals(0, $nid, 'The node ID was extracted from the URL.');
+      $node = Node::load($nid);
+      $this->assertNotNull($node, 'The node was loaded successfully.');
+      $this->assertFileExists(File::load($node->field_image->target_id)->getFileUri());
+    }
+  }
+
+}

core/modules/file/tests/src/Functional/FileFieldCreationTrait.php

@@ -0,0 +1,90 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+use Drupal\field\Entity\FieldStorageConfig;
+use Drupal\field\Entity\FieldConfig;
+
+/**
+ * Provides methods for creating file fields.
+ */
+trait FileFieldCreationTrait {
+
+  /**
+   * Creates a new file field.
+   *
+   * @param string $name
+   *   The name of the new field (all lowercase). The Field UI 'field_' prefix
+   *   is not added to the field name.
+   * @param string $entity_type
+   *   The entity type.
+   * @param string $bundle
+   *   The bundle that this field will be added to.
+   * @param array $storage_settings
+   *   A list of field storage settings that will be added to the defaults.
+   * @param array $field_settings
+   *   A list of instance settings that will be added to the instance defaults.
+   * @param array $widget_settings
+   *   A list of widget settings that will be added to the widget defaults.
+   *
+   * @return \Drupal\field\FieldStorageConfigInterface
+   *   The file field.
+   */
+  public function createFileField($name, $entity_type, $bundle, $storage_settings = [], $field_settings = [], $widget_settings = []) {
+    $field_storage = FieldStorageConfig::create([
+      'entity_type' => $entity_type,
+      'field_name' => $name,
+      'type' => 'file',
+      'settings' => $storage_settings,
+      'cardinality' => !empty($storage_settings['cardinality']) ? $storage_settings['cardinality'] : 1,
+    ]);
+    $field_storage->save();
+
+    $this->attachFileField($name, $entity_type, $bundle, $field_settings, $widget_settings);
+    return $field_storage;
+  }
+
+  /**
+   * Attaches a file field to an entity.
+   *
+   * @param string $name
+   *   The name of the new field (all lowercase). The Field UI 'field_' prefix
+   *   is not added to the field name.
+   * @param string $entity_type
+   *   The entity type this field will be added to.
+   * @param string $bundle
+   *   The bundle this field will be added to.
+   * @param array $field_settings
+   *   A list of field settings that will be added to the defaults.
+   * @param array $widget_settings
+   *   A list of widget settings that will be added to the widget defaults.
+   */
+  public function attachFileField($name, $entity_type, $bundle, $field_settings = [], $widget_settings = []) {
+    $field = [
+      'field_name' => $name,
+      'label' => $name,
+      'entity_type' => $entity_type,
+      'bundle' => $bundle,
+      'required' => !empty($field_settings['required']),
+      'settings' => $field_settings,
+    ];
+    FieldConfig::create($field)->save();
+
+    \Drupal::service('entity_display.repository')->getFormDisplay($entity_type, $bundle)
+      ->setComponent($name, [
+        'type' => 'file_generic',
+        'settings' => $widget_settings,
+      ])
+      ->save();
+    // Assign display settings.
+    \Drupal::service('entity_display.repository')->getViewDisplay($entity_type, $bundle)
+      ->setComponent($name, [
+        'label' => 'hidden',
+        'type' => 'file_default',
+      ])
+      ->save();
+  }
+
+}

core/modules/file/tests/src/Functional/FileFieldDisplayTest.php

@@ -0,0 +1,249 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+use Drupal\Core\Field\FieldStorageDefinitionInterface;
+use Drupal\file\Entity\File;
+use Drupal\node\Entity\Node;
+use Drupal\Tests\field_ui\Traits\FieldUiTestTrait;
+
+/**
+ * Tests the display of file fields in node and views.
+ *
+ * @group file
+ */
+class FileFieldDisplayTest extends FileFieldTestBase {
+
+  use FieldUiTestTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * Tests normal formatter display on node display.
+   */
+  public function testNodeDisplay(): void {
+    $field_name = $this->randomMachineName();
+    $type_name = 'article';
+    $field_storage_settings = [
+      'display_field' => '1',
+      'display_default' => '1',
+      'cardinality' => FieldStorageDefinitionInterface::CARDINALITY_UNLIMITED,
+    ];
+    $field_settings = [
+      'description_field' => '1',
+    ];
+    $widget_settings = [];
+    $this->createFileField($field_name, 'node', $type_name, $field_storage_settings, $field_settings, $widget_settings);
+
+    // Create a new node *without* the file field set, and check that the field
+    // is not shown for each node display.
+    $node = $this->drupalCreateNode(['type' => $type_name]);
+    // Check file_default last as the assertions below assume that this is the
+    // case.
+    $file_formatters = ['file_table', 'file_url_plain', 'hidden', 'file_default'];
+    foreach ($file_formatters as $formatter) {
+      if ($formatter === 'hidden') {
+        $edit = [
+          "fields[$field_name][region]" => 'hidden',
+        ];
+      }
+      else {
+        $edit = [
+          "fields[$field_name][type]" => $formatter,
+          "fields[$field_name][region]" => 'content',
+        ];
+      }
+      $this->drupalGet("admin/structure/types/manage/{$type_name}/display");
+      $this->submitForm($edit, 'Save');
+      $this->drupalGet('node/' . $node->id());
+      // Verify that the field label is hidden when no file is attached.
+      $this->assertSession()->pageTextNotContains($field_name);
+    }
+
+    $this->generateFile('escaped-&-text', 64, 10, 'text');
+    $test_file = File::create([
+      'uri' => 'public://escaped-&-text.txt',
+      'name' => 'escaped-&-text',
+      'filesize' => filesize('public://escaped-&-text.txt'),
+    ]);
+
+    // Create a new node with the uploaded file.
+    $nid = $this->uploadNodeFile($test_file, $field_name, $type_name);
+
+    // Check that the default formatter is displaying with the file name.
+    $node_storage = $this->container->get('entity_type.manager')->getStorage('node');
+    $node_storage->resetCache([$nid]);
+    $node = $node_storage->load($nid);
+    $node_file = File::load($node->{$field_name}->target_id);
+    $file_link = [
+      '#theme' => 'file_link',
+      '#file' => $node_file,
+    ];
+    $default_output = \Drupal::service('renderer')->renderRoot($file_link);
+    $this->assertSession()->responseContains($default_output);
+
+    // Turn the "display" option off and check that the file is no longer displayed.
+    $edit = [$field_name . '[0][display]' => FALSE];
+    $this->drupalGet('node/' . $nid . '/edit');
+    $this->submitForm($edit, 'Save');
+
+    $this->assertSession()->responseNotContains($default_output);
+
+    // Add a description and make sure that it is displayed.
+    $description = $this->randomMachineName();
+    $edit = [
+      $field_name . '[0][description]' => $description,
+      $field_name . '[0][display]' => TRUE,
+    ];
+    $this->drupalGet('node/' . $nid . '/edit');
+    $this->submitForm($edit, 'Save');
+    $this->assertSession()->pageTextContains($description);
+
+    // Ensure the filename in the link's title attribute is escaped.
+    $this->assertSession()->responseContains('title="escaped-&amp;-text.txt"');
+
+    // Test that fields appear as expected after during the preview.
+    // Add a second file.
+    $name = 'files[' . $field_name . '_1][]';
+    $edit_upload[$name] = \Drupal::service('file_system')->realpath($test_file->getFileUri());
+    $this->drupalGet("node/{$nid}/edit");
+    $this->submitForm($edit_upload, 'Upload');
+
+    // Uncheck the display checkboxes and go to the preview.
+    $edit[$field_name . '[0][display]'] = FALSE;
+    $edit[$field_name . '[1][display]'] = FALSE;
+    $this->submitForm($edit, 'Preview');
+    $this->clickLink('Back to content editing');
+    // First file.
+    $this->assertSession()->responseContains($field_name . '[0][display]');
+    // Second file.
+    $this->assertSession()->responseContains($field_name . '[1][display]');
+    $this->assertSession()->responseContains($field_name . '[1][description]');
+
+    // Check that the file fields don't contain duplicate HTML IDs.
+    $this->assertSession()->pageContainsNoDuplicateId();
+  }
+
+  /**
+   * Tests default display of File Field.
+   */
+  public function testDefaultFileFieldDisplay(): void {
+    $field_name = $this->randomMachineName();
+    $type_name = 'article';
+    $field_storage_settings = [
+      'display_field' => '1',
+      'display_default' => '0',
+      'cardinality' => FieldStorageDefinitionInterface::CARDINALITY_UNLIMITED,
+    ];
+    $field_settings = [
+      'description_field' => '1',
+    ];
+    $widget_settings = [];
+    $this->createFileField($field_name, 'node', $type_name, $field_storage_settings, $field_settings, $widget_settings);
+
+    $test_file = $this->getTestFile('text');
+
+    // Create a new node with the uploaded file.
+    $nid = $this->uploadNodeFile($test_file, $field_name, $type_name);
+
+    $this->drupalGet('node/' . $nid . '/edit');
+    $this->assertSession()->fieldExists($field_name . '[0][display]');
+    $this->assertSession()->checkboxNotChecked($field_name . '[0][display]');
+  }
+
+  /**
+   * Tests description toggle for field instance configuration.
+   */
+  public function testDescToggle(): void {
+    $type_name = 'test';
+    $field_type = 'file';
+    $field_name = $this->randomMachineName();
+    // Use the UI to add a new content type that also contains a file field.
+    $edit = [
+      'name' => $type_name,
+      'type' => $type_name,
+    ];
+    $this->drupalGet('admin/structure/types/add');
+    $this->submitForm($edit, 'Save and manage fields');
+    $field_edit = [
+      'settings[description_field]' => TRUE,
+    ];
+    $this->fieldUIAddNewField('/admin/structure/types/manage/' . $type_name, $field_name, $this->randomString(), $field_type, [], $field_edit);
+    // Add a node of our new type and upload a file to it.
+    $file = current($this->drupalGetTestFiles('text'));
+    $title = $this->randomString();
+    $edit = [
+      'title[0][value]' => $title,
+      'files[field_' . $field_name . '_0]' => \Drupal::service('file_system')->realpath($file->uri),
+    ];
+    $this->drupalGet('node/add/' . $type_name);
+    $this->submitForm($edit, 'Save');
+    $node = $this->drupalGetNodeByTitle($title);
+    $this->drupalGet('node/' . $node->id() . '/edit');
+    $this->assertSession()->pageTextContains('The description may be used as the label of the link to the file.');
+  }
+
+  /**
+   * Tests description display of File Field.
+   */
+  public function testDescriptionDefaultFileFieldDisplay(): void {
+    $field_name = $this->randomMachineName();
+    $type_name = 'article';
+    $field_storage_settings = [
+      'display_field' => '1',
+      'display_default' => '1',
+      'cardinality' => FieldStorageDefinitionInterface::CARDINALITY_UNLIMITED,
+    ];
+    $field_settings = [
+      'description_field' => '1',
+    ];
+    $widget_settings = [];
+    $this->createFileField($field_name, 'node', $type_name, $field_storage_settings, $field_settings, $widget_settings);
+
+    $test_file = $this->getTestFile('text');
+
+    // Create a new node with the uploaded file.
+    $nid = $this->uploadNodeFile($test_file, $field_name, $type_name);
+
+    // Add file description.
+    $description = 'This is the test file description';
+    $this->drupalGet("node/{$nid}/edit");
+    $this->submitForm([
+      $field_name . '[0][description]' => $description,
+    ], 'Save');
+
+    // Load uncached node.
+    \Drupal::entityTypeManager()->getStorage('node')->resetCache([$nid]);
+    $node = Node::load($nid);
+
+    // Test default formatter.
+    $this->drupalGet('node/' . $nid);
+    $this->assertSession()->elementTextContains('xpath', '//a[@href="' . $node->{$field_name}->entity->createFileUrl() . '"]', $description);
+
+    // Change formatter to "Table of files".
+    $display = \Drupal::entityTypeManager()->getStorage('entity_view_display')->load('node.' . $type_name . '.default');
+    $display->setComponent($field_name, [
+      'label' => 'hidden',
+      'type' => 'file_table',
+    ])->save();
+
+    $this->drupalGet('node/' . $nid);
+    $this->assertSession()->elementTextContains('xpath', '//a[@href="' . $node->{$field_name}->entity->createFileUrl() . '"]', $description);
+
+    // Test that null file size is rendered as "Unknown".
+    $nonexistent_file = File::create([
+      'uri' => 'temporary://' . $this->randomMachineName() . '.txt',
+    ]);
+    $nonexistent_file->save();
+    $node->set($field_name, $nonexistent_file->id());
+    $node->save();
+    $this->drupalGet('node/' . $nid);
+    $this->assertSession()->elementTextEquals('xpath', '//a[@href="' . $node->{$field_name}->entity->createFileUrl() . '"]/../../../td[2]', 'Unknown');
+  }
+
+}

core/modules/file/tests/src/Functional/FileFieldFormatterAccessTest.php

@@ -0,0 +1,40 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+/**
+ * Tests file formatter access.
+ * @group file
+ */
+class FileFieldFormatterAccessTest extends FileFieldTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  protected static $modules = ['node', 'file', 'field_ui', 'file_test'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * Tests the custom access handler is invoked.
+   */
+  public function testFileAccessHandler(): void {
+    $type_name = 'article';
+    $field_name = $this->randomMachineName();
+    $this->createFileField($field_name, 'node', $type_name);
+    \Drupal::state()->set('file_test_alternate_access_handler', TRUE);
+    \Drupal::entityTypeManager()->clearCachedDefinitions();
+    $test_file = $this->getTestFile('text');
+    $nid = $this->uploadNodeFile($test_file, $field_name, $type_name);
+    $this->drupalGet('node/' . $nid);
+    $this->assertTrue(\Drupal::state()->get('file_access_formatter_check', FALSE));
+  }
+
+}

core/modules/file/tests/src/Functional/FileFieldPathTest.php

@@ -0,0 +1,103 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+use Drupal\file\Entity\File;
+
+/**
+ * Tests that files are uploaded to proper locations.
+ *
+ * @group file
+ */
+class FileFieldPathTest extends FileFieldTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * Tests the normal formatter display on node display.
+   */
+  public function testUploadPath(): void {
+    /** @var \Drupal\node\NodeStorageInterface $node_storage */
+    $node_storage = $this->container->get('entity_type.manager')->getStorage('node');
+    $field_name = $this->randomMachineName();
+    $type_name = 'article';
+    $this->createFileField($field_name, 'node', $type_name);
+    /** @var \Drupal\file\FileInterface $test_file */
+    $test_file = $this->getTestFile('text');
+
+    // Create a new node.
+    $nid = $this->uploadNodeFile($test_file, $field_name, $type_name);
+
+    // Check that the file was uploaded to the correct location.
+    $node_storage->resetCache([$nid]);
+    $node = $node_storage->load($nid);
+    /** @var \Drupal\file\FileInterface $node_file */
+    $node_file = $node->{$field_name}->entity;
+    $date_formatter = $this->container->get('date.formatter');
+    $expected_filename =
+      'public://' .
+      $date_formatter->format(\Drupal::time()->getRequestTime(), 'custom', 'Y') . '-' .
+      $date_formatter->format(\Drupal::time()->getRequestTime(), 'custom', 'm') . '/' .
+      $test_file->getFilename();
+    $this->assertPathMatch($expected_filename, $node_file->getFileUri(), "The file {$node_file->getFileUri()} was uploaded to the correct path.");
+
+    // Change the path to contain multiple subdirectories.
+    $this->updateFileField($field_name, $type_name, ['file_directory' => 'foo/bar/baz']);
+
+    // Upload a new file into the subdirectories.
+    $nid = $this->uploadNodeFile($test_file, $field_name, $type_name);
+
+    // Check that the file was uploaded into the subdirectory.
+    $node_storage->resetCache([$nid]);
+    $node = $node_storage->load($nid);
+    $node_file = File::load($node->{$field_name}->target_id);
+    $this->assertPathMatch('public://foo/bar/baz/' . $test_file->getFilename(), $node_file->getFileUri(), "The file {$node_file->getFileUri()} was uploaded to the correct path.");
+
+    // Check the path when used with tokens.
+    // Change the path to contain multiple token directories.
+    $this->updateFileField($field_name, $type_name, ['file_directory' => '[current-user:uid]/[current-user:name]']);
+
+    // Upload a new file into the token subdirectories.
+    $nid = $this->uploadNodeFile($test_file, $field_name, $type_name);
+
+    // Check that the file was uploaded into the subdirectory.
+    $node_storage->resetCache([$nid]);
+    $node = $node_storage->load($nid);
+    $node_file = File::load($node->{$field_name}->target_id);
+    // Do token replacement using the same user which uploaded the file, not
+    // the user running the test case.
+    $data = ['user' => $this->adminUser];
+    $subdirectory = \Drupal::token()->replace('[user:uid]/[user:name]', $data);
+    $this->assertPathMatch('public://' . $subdirectory . '/' . $test_file->getFilename(), $node_file->getFileUri(), "The file {$node_file->getFileUri()} was uploaded to the correct path with token replacements.");
+  }
+
+  /**
+   * Asserts that a file is uploaded to the right location.
+   *
+   * @param string $expected_path
+   *   The location where the file is expected to be uploaded. Duplicate file
+   *   names to not need to be taken into account.
+   * @param string $actual_path
+   *   Where the file was actually uploaded.
+   * @param string $message
+   *   The message to display with this assertion.
+   *
+   * @internal
+   */
+  public function assertPathMatch(string $expected_path, string $actual_path, string $message): void {
+    // Strip off the extension of the expected path to allow for _0, _1, etc.
+    // suffixes when the file hits a duplicate name.
+    $pos = strrpos($expected_path, '.');
+    $base_path = substr($expected_path, 0, $pos);
+    $extension = substr($expected_path, $pos + 1);
+
+    $result = (bool) preg_match('/' . preg_quote($base_path, '/') . '(_[0-9]+)?\.' . preg_quote($extension, '/') . '/', $actual_path);
+    $this->assertTrue($result, $message);
+  }
+
+}

core/modules/file/tests/src/Functional/FileFieldRSSContentTest.php

@@ -0,0 +1,77 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+use Drupal\file\Entity\File;
+
+/**
+ * Ensure that files added to nodes appear correctly in RSS feeds.
+ *
+ * @group file
+ */
+class FileFieldRSSContentTest extends FileFieldTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  protected static $modules = ['node', 'views'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * Tests RSS enclosure formatter display for RSS feeds.
+   */
+  public function testFileFieldRSSContent(): void {
+    $node_storage = $this->container->get('entity_type.manager')->getStorage('node');
+    $field_name = $this->randomMachineName();
+    $type_name = 'article';
+
+    $this->createFileField($field_name, 'node', $type_name);
+
+    // RSS display must be added manually.
+    $this->drupalGet("admin/structure/types/manage/$type_name/display");
+    $edit = [
+      "display_modes_custom[rss]" => '1',
+    ];
+    $this->submitForm($edit, 'Save');
+
+    // Change the format to 'RSS enclosure'.
+    $this->drupalGet("admin/structure/types/manage/$type_name/display/rss");
+    $edit = [
+      "fields[$field_name][type]" => 'file_rss_enclosure',
+      "fields[$field_name][region]" => 'content',
+    ];
+    $this->submitForm($edit, 'Save');
+
+    // Create a new node with a file field set. Promote to frontpage
+    // needs to be set so this node will appear in the RSS feed.
+    $node = $this->drupalCreateNode(['type' => $type_name, 'promote' => 1]);
+    $test_file = $this->getTestFile('text');
+
+    // Create a new node with the uploaded file.
+    $nid = $this->uploadNodeFile($test_file, $field_name, $node->id());
+
+    // Get the uploaded file from the node.
+    $node_storage->resetCache([$nid]);
+    $node = $node_storage->load($nid);
+    $node_file = File::load($node->{$field_name}->target_id);
+
+    // Check that the RSS enclosure appears in the RSS feed.
+    $this->drupalGet('rss.xml');
+    $selector = sprintf(
+      '//enclosure[@url="%s" and @length="%s" and @type="%s"]',
+      $node_file->createFileUrl(FALSE),
+      $node_file->getSize(),
+      $node_file->getMimeType()
+    );
+    $this->assertNotEmpty($this->getSession()->getDriver()->find($selector), 'File field RSS enclosure is displayed when viewing the RSS feed.');
+  }
+
+}

core/modules/file/tests/src/Functional/FileFieldRevisionTest.php

@@ -0,0 +1,157 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+use Drupal\Core\Database\Database;
+use Drupal\file\Entity\File;
+
+/**
+ * Tests creating and deleting revisions with files attached.
+ *
+ * @group file
+ */
+class FileFieldRevisionTest extends FileFieldTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * Tests creating multiple revisions of a node and managing attached files.
+   *
+   * Expected behaviors:
+   *  - Adding a new revision will make another entry in the field table, but
+   *    the original file will not be duplicated.
+   *  - Deleting a revision should not delete the original file if the file
+   *    is in use by another revision.
+   *  - When the last revision that uses a file is deleted, the original file
+   *    should be deleted also.
+   */
+  public function testRevisions(): void {
+    // This test expects unused managed files to be marked as a temporary file
+    // and then deleted up by file_cron().
+    $this->config('file.settings')
+      ->set('make_unused_managed_files_temporary', TRUE)
+      ->save();
+    $node_storage = $this->container->get('entity_type.manager')->getStorage('node');
+    $type_name = 'article';
+    $field_name = $this->randomMachineName();
+    $this->createFileField($field_name, 'node', $type_name);
+    // Create the same fields for users.
+    $this->createFileField($field_name, 'user', 'user');
+
+    $test_file = $this->getTestFile('text');
+
+    // Create a new node with the uploaded file.
+    $nid = $this->uploadNodeFile($test_file, $field_name, $type_name);
+
+    // Check that the file exists on disk and in the database.
+    $node_storage->resetCache([$nid]);
+    $node = $node_storage->load($nid);
+    $node_file_r1 = File::load($node->{$field_name}->target_id);
+    $node_vid_r1 = $node->getRevisionId();
+    $this->assertFileExists($node_file_r1->getFileUri());
+    $this->assertFileEntryExists($node_file_r1, 'File entry exists in database on node creation.');
+    $this->assertFileIsPermanent($node_file_r1, 'File is permanent.');
+
+    // Upload another file to the same node in a new revision.
+    $this->replaceNodeFile($test_file, $field_name, $nid);
+    $node_storage->resetCache([$nid]);
+    $node = $node_storage->load($nid);
+    $node_file_r2 = File::load($node->{$field_name}->target_id);
+    $node_vid_r2 = $node->getRevisionId();
+    $this->assertFileExists($node_file_r2->getFileUri());
+    $this->assertFileEntryExists($node_file_r2, 'Replacement file entry exists in database after creating new revision.');
+    $this->assertFileIsPermanent($node_file_r2, 'Replacement file is permanent.');
+
+    // Check that the original file is still in place on the first revision.
+    $node = $node_storage->loadRevision($node_vid_r1);
+    $current_file = File::load($node->{$field_name}->target_id);
+    $this->assertEquals($node_file_r1->id(), $current_file->id(), 'Original file still in place after replacing file in new revision.');
+    $this->assertFileExists($node_file_r1->getFileUri());
+    $this->assertFileEntryExists($node_file_r1, 'Original file entry still in place after replacing file in new revision');
+    $this->assertFileIsPermanent($node_file_r1, 'Original file is still permanent.');
+
+    // Save a new version of the node without any changes.
+    // Check that the file is still the same as the previous revision.
+    $this->drupalGet('node/' . $nid . '/edit');
+    $this->submitForm(['revision' => '1'], 'Save');
+    $node_storage->resetCache([$nid]);
+    $node = $node_storage->load($nid);
+    $node_file_r3 = File::load($node->{$field_name}->target_id);
+    $node_vid_r3 = $node->getRevisionId();
+    $this->assertEquals($node_file_r2->id(), $node_file_r3->id(), 'Previous revision file still in place after creating a new revision without a new file.');
+    $this->assertFileIsPermanent($node_file_r3, 'New revision file is permanent.');
+
+    // Revert to the first revision and check that the original file is active.
+    $this->drupalGet('node/' . $nid . '/revisions/' . $node_vid_r1 . '/revert');
+    $this->submitForm([], 'Revert');
+    $node_storage->resetCache([$nid]);
+    $node = $node_storage->load($nid);
+    $node_file_r4 = File::load($node->{$field_name}->target_id);
+    $this->assertEquals($node_file_r1->id(), $node_file_r4->id(), 'Original revision file still in place after reverting to the original revision.');
+    $this->assertFileIsPermanent($node_file_r4, 'Original revision file still permanent after reverting to the original revision.');
+
+    // Delete the second revision and check that the file is kept (since it is
+    // still being used by the third revision).
+    $this->drupalGet('node/' . $nid . '/revisions/' . $node_vid_r2 . '/delete');
+    $this->submitForm([], 'Delete');
+    $this->assertFileExists($node_file_r3->getFileUri());
+    $this->assertFileEntryExists($node_file_r3, 'Second file entry is still available after deleting second revision, since it is being used by the third revision.');
+    $this->assertFileIsPermanent($node_file_r3, 'Second file entry is still permanent after deleting second revision, since it is being used by the third revision.');
+
+    // Attach the second file to a user.
+    $user = $this->drupalCreateUser();
+    $user->$field_name->target_id = $node_file_r3->id();
+    $user->$field_name->display = 1;
+    $user->save();
+    $this->drupalGet('user/' . $user->id() . '/edit');
+
+    // Delete the third revision and check that the file is not deleted yet.
+    $this->drupalGet('node/' . $nid . '/revisions/' . $node_vid_r3 . '/delete');
+    $this->submitForm([], 'Delete');
+    $this->assertFileExists($node_file_r3->getFileUri());
+    $this->assertFileEntryExists($node_file_r3, 'Second file entry is still available after deleting third revision, since it is being used by the user.');
+    $this->assertFileIsPermanent($node_file_r3, 'Second file entry is still permanent after deleting third revision, since it is being used by the user.');
+
+    // Delete the user and check that the file is also deleted.
+    $user->delete();
+
+    // Call file_cron() to clean up the file. Make sure the changed timestamp
+    // of the file is older than the system.file.temporary_maximum_age
+    // configuration value. We use an UPDATE statement because using the API
+    // would set the timestamp.
+    $connection = Database::getConnection();
+    $connection->update('file_managed')
+      ->fields([
+        'changed' => \Drupal::time()->getRequestTime() - ($this->config('system.file')->get('temporary_maximum_age') + 1),
+      ])
+      ->condition('fid', $node_file_r3->id())
+      ->execute();
+    \Drupal::service('cron')->run();
+
+    $this->assertFileDoesNotExist($node_file_r3->getFileUri());
+    $this->assertFileEntryNotExists($node_file_r3, 'Second file entry is now deleted after deleting third revision, since it is no longer being used by any other nodes.');
+
+    // Delete the entire node and check that the original file is deleted.
+    $this->drupalGet('node/' . $nid . '/delete');
+    $this->submitForm([], 'Delete');
+    // Call file_cron() to clean up the file. Make sure the changed timestamp
+    // of the file is older than the system.file.temporary_maximum_age
+    // configuration value. We use an UPDATE statement because using the API
+    // would set the timestamp.
+    $connection->update('file_managed')
+      ->fields([
+        'changed' => \Drupal::time()->getRequestTime() - ($this->config('system.file')->get('temporary_maximum_age') + 1),
+      ])
+      ->condition('fid', $node_file_r1->id())
+      ->execute();
+    \Drupal::service('cron')->run();
+    $this->assertFileDoesNotExist($node_file_r1->getFileUri());
+    $this->assertFileEntryNotExists($node_file_r1, 'Original file entry is deleted after deleting the entire node with two revisions remaining.');
+  }
+
+}

core/modules/file/tests/src/Functional/FileFieldTestBase.php

@@ -0,0 +1,248 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+use Drupal\Component\Render\FormattableMarkup;
+use Drupal\field\Entity\FieldStorageConfig;
+use Drupal\field\Entity\FieldConfig;
+use Drupal\file\FileInterface;
+use Drupal\Tests\BrowserTestBase;
+use Drupal\file\Entity\File;
+use Drupal\Tests\TestFileCreationTrait;
+
+/**
+ * Provides methods specifically for testing File module's field handling.
+ */
+abstract class FileFieldTestBase extends BrowserTestBase {
+
+  use FileFieldCreationTrait;
+  use TestFileCreationTrait {
+    getTestFiles as drupalGetTestFiles;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['node', 'file', 'file_module_test', 'field_ui'];
+
+  /**
+   * A user with administration permissions.
+   *
+   * @var \Drupal\user\UserInterface
+   */
+  protected $adminUser;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    $this->adminUser = $this->drupalCreateUser([
+      'access content',
+      'access administration pages',
+      'administer site configuration',
+      'administer users',
+      'administer permissions',
+      'administer content types',
+      'administer node fields',
+      'administer node display',
+      'administer nodes',
+      'bypass node access',
+    ]);
+    $this->drupalLogin($this->adminUser);
+    $this->drupalCreateContentType(['type' => 'article', 'name' => 'Article']);
+  }
+
+  /**
+   * Retrieves a sample file of the specified type.
+   *
+   * @return \Drupal\file\FileInterface
+   *   The new unsaved file entity.
+   */
+  public function getTestFile($type_name, $size = NULL) {
+    // Get a file to upload.
+    $file = current($this->drupalGetTestFiles($type_name, $size));
+
+    // Add a filesize property to files as would be read by
+    // \Drupal\file\Entity\File::load().
+    $file->filesize = filesize($file->uri);
+
+    return File::create((array) $file);
+  }
+
+  /**
+   * Retrieves the fid of the last inserted file.
+   */
+  public function getLastFileId() {
+    return (int) \Drupal::entityQueryAggregate('file')
+      ->accessCheck(FALSE)
+      ->aggregate('fid', 'max')
+      ->execute()[0]['fid_max'];
+  }
+
+  /**
+   * Updates an existing file field with new settings.
+   */
+  public function updateFileField($name, $type_name, $field_settings = [], $widget_settings = []) {
+    $field = FieldConfig::loadByName('node', $type_name, $name);
+    $field->setSettings(array_merge($field->getSettings(), $field_settings));
+    $field->save();
+
+    \Drupal::service('entity_display.repository')->getFormDisplay('node', $type_name)
+      ->setComponent($name, [
+        'settings' => $widget_settings,
+      ])
+      ->save();
+  }
+
+  /**
+   * Uploads a file to a node.
+   *
+   * @param \Drupal\file\FileInterface $file
+   *   The File to be uploaded.
+   * @param string $field_name
+   *   The name of the field on which the files should be saved.
+   * @param $nid_or_type
+   *   A numeric node id to upload files to an existing node, or a string
+   *   indicating the desired bundle for a new node.
+   * @param bool $new_revision
+   *   The revision number.
+   * @param array $extras
+   *   Additional values when a new node is created.
+   *
+   * @return int
+   *   The node id.
+   */
+  public function uploadNodeFile(FileInterface $file, $field_name, $nid_or_type, $new_revision = TRUE, array $extras = []) {
+    return $this->uploadNodeFiles([$file], $field_name, $nid_or_type, $new_revision, $extras);
+  }
+
+  /**
+   * Uploads multiple files to a node.
+   *
+   * @param \Drupal\file\FileInterface[] $files
+   *   The files to be uploaded.
+   * @param string $field_name
+   *   The name of the field on which the files should be saved.
+   * @param $nid_or_type
+   *   A numeric node id to upload files to an existing node, or a string
+   *   indicating the desired bundle for a new node.
+   * @param bool $new_revision
+   *   The revision number.
+   * @param array $extras
+   *   Additional values when a new node is created.
+   *
+   * @return int
+   *   The node id.
+   */
+  public function uploadNodeFiles(array $files, $field_name, $nid_or_type, $new_revision = TRUE, array $extras = []) {
+    $edit = [
+      'title[0][value]' => $this->randomMachineName(),
+      'revision' => (string) (int) $new_revision,
+    ];
+
+    $node_storage = $this->container->get('entity_type.manager')->getStorage('node');
+    if (is_numeric($nid_or_type)) {
+      $nid = $nid_or_type;
+      $node_storage->resetCache([$nid]);
+      $node = $node_storage->load($nid);
+    }
+    else {
+      // Add a new node.
+      $extras['type'] = $nid_or_type;
+      $node = $this->drupalCreateNode($extras);
+      $nid = $node->id();
+      // Save at least one revision to better simulate a real site.
+      $node->setNewRevision();
+      $node->save();
+      $node_storage->resetCache([$nid]);
+      $node = $node_storage->load($nid);
+      $this->assertNotEquals($nid, $node->getRevisionId(), 'Node revision exists.');
+    }
+    $this->drupalGet("node/$nid/edit");
+    $page = $this->getSession()->getPage();
+
+    // Attach files to the node.
+    $field_storage = FieldStorageConfig::loadByName('node', $field_name);
+    // File input name depends on number of files already uploaded.
+    $field_num = count($node->{$field_name});
+    foreach ($files as $i => $file) {
+      $delta = $field_num + $i;
+      $file_path = $this->container->get('file_system')->realpath($file->getFileUri());
+      $name = 'files[' . $field_name . '_' . $delta . ']';
+      if ($field_storage->getCardinality() != 1) {
+        $name .= '[]';
+      }
+      if (count($files) == 1) {
+        $edit[$name] = $file_path;
+      }
+      else {
+        $page->attachFileToField($name, $file_path);
+        $this->submitForm([], 'Upload');
+      }
+    }
+
+    $this->submitForm($edit, 'Save');
+
+    return $nid;
+  }
+
+  /**
+   * Removes a file from a node.
+   *
+   * Note that if replacing a file, it must first be removed then added again.
+   */
+  public function removeNodeFile($nid, $new_revision = TRUE) {
+    $edit = [
+      'revision' => (string) (int) $new_revision,
+    ];
+
+    $this->drupalGet('node/' . $nid . '/edit');
+    $this->submitForm([], 'Remove');
+    $this->submitForm($edit, 'Save');
+  }
+
+  /**
+   * Replaces a file within a node.
+   */
+  public function replaceNodeFile($file, $field_name, $nid, $new_revision = TRUE) {
+    $edit = [
+      'files[' . $field_name . '_0]' => \Drupal::service('file_system')->realpath($file->getFileUri()),
+      'revision' => (string) (int) $new_revision,
+    ];
+
+    $this->drupalGet('node/' . $nid . '/edit');
+    $this->submitForm([], 'Remove');
+    $this->submitForm($edit, 'Save');
+  }
+
+  /**
+   * Asserts that a file exists in the database.
+   */
+  public function assertFileEntryExists($file, $message = NULL) {
+    $this->container->get('entity_type.manager')->getStorage('file')->resetCache();
+    $db_file = File::load($file->id());
+    $message = $message ?? new FormattableMarkup('File %file exists in database at the correct path.', ['%file' => $file->getFileUri()]);
+    $this->assertEquals($file->getFileUri(), $db_file->getFileUri(), $message);
+  }
+
+  /**
+   * Asserts that a file does not exist in the database.
+   */
+  public function assertFileEntryNotExists($file, $message) {
+    $this->container->get('entity_type.manager')->getStorage('file')->resetCache();
+    $message = $message ?? new FormattableMarkup('File %file exists in database at the correct path.', ['%file' => $file->getFileUri()]);
+    $this->assertNull(File::load($file->id()), $message);
+  }
+
+  /**
+   * Asserts that a file's status is set to permanent in the database.
+   */
+  public function assertFileIsPermanent(FileInterface $file, $message = NULL) {
+    $message = $message ?? new FormattableMarkup('File %file is permanent.', ['%file' => $file->getFileUri()]);
+    $this->assertTrue($file->isPermanent(), $message);
+  }
+
+}

core/modules/file/tests/src/Functional/FileFieldValidateTest.php

@@ -0,0 +1,202 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+use Drupal\Core\Field\FieldStorageDefinitionInterface;
+use Drupal\Core\StringTranslation\ByteSizeMarkup;
+use Drupal\field\Entity\FieldConfig;
+use Drupal\file\Entity\File;
+
+/**
+ * Tests file field validation functions.
+ *
+ * Values validated include the file type, max file size, max size per node,
+ * and whether the field is required.
+ *
+ * @group file
+ */
+class FileFieldValidateTest extends FileFieldTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * Tests the required property on file fields.
+   */
+  public function testRequired(): void {
+    $node_storage = $this->container->get('entity_type.manager')->getStorage('node');
+    $type_name = 'article';
+    $field_name = $this->randomMachineName();
+    $storage = $this->createFileField($field_name, 'node', $type_name, [], ['required' => '1']);
+    $field = FieldConfig::loadByName('node', $type_name, $field_name);
+
+    $test_file = $this->getTestFile('text');
+
+    // Try to post a new node without uploading a file.
+    $edit = [];
+    $edit['title[0][value]'] = $this->randomMachineName();
+    $this->drupalGet('node/add/' . $type_name);
+    $this->submitForm($edit, 'Save');
+    $this->assertSession()->pageTextContains("{$field->getLabel()} field is required.");
+
+    // Create a new node with the uploaded file.
+    $nid = $this->uploadNodeFile($test_file, $field_name, $type_name);
+    $this->assertNotFalse($nid, "uploadNodeFile({$test_file->getFileUri()}, $field_name, $type_name) succeeded");
+
+    $node_storage->resetCache([$nid]);
+    $node = $node_storage->load($nid);
+
+    $node_file = File::load($node->{$field_name}->target_id);
+    $this->assertFileExists($node_file->getFileUri());
+    $this->assertFileEntryExists($node_file, 'File entry exists after uploading to the required field.');
+
+    // Try again with a multiple value field.
+    $storage->delete();
+    $this->createFileField($field_name, 'node', $type_name, ['cardinality' => FieldStorageDefinitionInterface::CARDINALITY_UNLIMITED], ['required' => '1']);
+
+    // Try to post a new node without uploading a file in the multivalue field.
+    $edit = [];
+    $edit['title[0][value]'] = $this->randomMachineName();
+    $this->drupalGet('node/add/' . $type_name);
+    $this->submitForm($edit, 'Save');
+    $this->assertSession()->pageTextContains("{$field->getLabel()} field is required.");
+
+    // Create a new node with the uploaded file into the multivalue field.
+    $nid = $this->uploadNodeFile($test_file, $field_name, $type_name);
+    $node_storage->resetCache([$nid]);
+    $node = $node_storage->load($nid);
+    $node_file = File::load($node->{$field_name}->target_id);
+    $this->assertFileExists($node_file->getFileUri());
+    $this->assertFileEntryExists($node_file, 'File entry exists after uploading to the required multiple value field.');
+  }
+
+  /**
+   * Tests the max file size validator.
+   */
+  public function testFileMaxSize(): void {
+    $node_storage = $this->container->get('entity_type.manager')->getStorage('node');
+    $type_name = 'article';
+    $field_name = $this->randomMachineName();
+    $this->createFileField($field_name, 'node', $type_name, [], ['required' => '1']);
+
+    // 128KB.
+    $small_file = $this->getTestFile('text', 131072);
+    // 1.2MB
+    $large_file = $this->getTestFile('text', 1310720);
+
+    // Test uploading both a large and small file with different increments.
+    $sizes = [
+      '1M' => 1048576,
+      '1024K' => 1048576,
+      '1048576' => 1048576,
+    ];
+
+    foreach ($sizes as $max_filesize => $file_limit) {
+      // Set the max file upload size.
+      $this->updateFileField($field_name, $type_name, ['max_filesize' => $max_filesize]);
+
+      // Create a new node with the small file, which should pass.
+      $nid = $this->uploadNodeFile($small_file, $field_name, $type_name);
+      $node_storage->resetCache([$nid]);
+      $node = $node_storage->load($nid);
+      $node_file = File::load($node->{$field_name}->target_id);
+      $this->assertFileExists($node_file->getFileUri());
+      $this->assertFileEntryExists($node_file, sprintf('File entry exists after uploading a file (%s) under the max limit (%s).', ByteSizeMarkup::create($small_file->getSize()), $max_filesize));
+
+      // Check that uploading the large file fails (1M limit).
+      $this->uploadNodeFile($large_file, $field_name, $type_name);
+      $filesize = ByteSizeMarkup::create($large_file->getSize());
+      $maxsize = ByteSizeMarkup::create($file_limit);
+      $this->assertSession()->pageTextContains("The file is {$filesize} exceeding the maximum file size of {$maxsize}.");
+    }
+
+    // Turn off the max filesize.
+    $this->updateFileField($field_name, $type_name, ['max_filesize' => '']);
+
+    // Upload the big file successfully.
+    $nid = $this->uploadNodeFile($large_file, $field_name, $type_name);
+    $node_storage->resetCache([$nid]);
+    $node = $node_storage->load($nid);
+    $node_file = File::load($node->{$field_name}->target_id);
+    $this->assertFileExists($node_file->getFileUri());
+    $this->assertFileEntryExists($node_file, sprintf('File entry exists after uploading a file (%s) with no max limit.', ByteSizeMarkup::create($large_file->getSize())));
+  }
+
+  /**
+   * Tests file extension checking.
+   */
+  public function testFileExtension(): void {
+    $node_storage = $this->container->get('entity_type.manager')->getStorage('node');
+    $type_name = 'article';
+    $field_name = $this->randomMachineName();
+    $this->createFileField($field_name, 'node', $type_name);
+
+    $test_file = $this->getTestFile('image');
+    [, $test_file_extension] = explode('.', $test_file->getFilename());
+
+    // Disable extension checking.
+    $this->updateFileField($field_name, $type_name, ['file_extensions' => '']);
+
+    // Check that the file can be uploaded with no extension checking.
+    $nid = $this->uploadNodeFile($test_file, $field_name, $type_name);
+    $node_storage->resetCache([$nid]);
+    $node = $node_storage->load($nid);
+    $node_file = File::load($node->{$field_name}->target_id);
+    $this->assertFileExists($node_file->getFileUri());
+    $this->assertFileEntryExists($node_file, 'File entry exists after uploading a file with no extension checking.');
+
+    // Enable extension checking for text files.
+    $this->updateFileField($field_name, $type_name, ['file_extensions' => 'txt']);
+
+    // Check that the file with the wrong extension cannot be uploaded.
+    $this->uploadNodeFile($test_file, $field_name, $type_name);
+    $this->assertSession()->pageTextContains("Only files with the following extensions are allowed: txt.");
+
+    // Enable extension checking for text and image files.
+    $this->updateFileField($field_name, $type_name, ['file_extensions' => "txt $test_file_extension"]);
+
+    // Check that the file can be uploaded with extension checking.
+    $nid = $this->uploadNodeFile($test_file, $field_name, $type_name);
+    $node_storage->resetCache([$nid]);
+    $node = $node_storage->load($nid);
+    $node_file = File::load($node->{$field_name}->target_id);
+    $this->assertFileExists($node_file->getFileUri());
+    $this->assertFileEntryExists($node_file, 'File entry exists after uploading a file with extension checking.');
+  }
+
+  /**
+   * Checks that a file can always be removed if it does not pass validation.
+   */
+  public function testFileRemoval(): void {
+    $node_storage = $this->container->get('entity_type.manager')->getStorage('node');
+    $type_name = 'article';
+    $field_name = 'file_test';
+    $this->createFileField($field_name, 'node', $type_name);
+
+    $test_file = $this->getTestFile('image');
+
+    // Disable extension checking.
+    $this->updateFileField($field_name, $type_name, ['file_extensions' => '']);
+
+    // Check that the file can be uploaded with no extension checking.
+    $nid = $this->uploadNodeFile($test_file, $field_name, $type_name);
+    $node_storage->resetCache([$nid]);
+    $node = $node_storage->load($nid);
+    $node_file = File::load($node->{$field_name}->target_id);
+    $this->assertFileExists($node_file->getFileUri());
+    $this->assertFileEntryExists($node_file, 'File entry exists after uploading a file with no extension checking.');
+
+    // Enable extension checking for text files.
+    $this->updateFileField($field_name, $type_name, ['file_extensions' => 'txt']);
+
+    // Check that the file can still be removed.
+    $this->removeNodeFile($nid);
+    $this->assertSession()->pageTextNotContains('Only files with the following extensions are allowed: txt.');
+    $this->assertSession()->pageTextContains('Article ' . $node->getTitle() . ' has been updated.');
+  }
+
+}

core/modules/file/tests/src/Functional/FileFieldWidgetTest.php

@@ -0,0 +1,614 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+use Drupal\comment\Entity\Comment;
+use Drupal\comment\Tests\CommentTestTrait;
+use Drupal\Component\Serialization\Json;
+use Drupal\Core\Url;
+use Drupal\field\Entity\FieldConfig;
+use Drupal\field\Entity\FieldStorageConfig;
+use Drupal\Tests\field_ui\Traits\FieldUiTestTrait;
+use Drupal\user\RoleInterface;
+use Drupal\file\Entity\File;
+use Drupal\user\Entity\User;
+use Drupal\user\UserInterface;
+
+/**
+ * Tests the file field widget with public and private files.
+ *
+ * @group file
+ * @group #slow
+ */
+class FileFieldWidgetTest extends FileFieldTestBase {
+
+  use CommentTestTrait;
+  use FieldUiTestTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['comment', 'block'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    $this->drupalPlaceBlock('system_breadcrumb_block');
+  }
+
+  /**
+   * Creates a temporary file, for a specific user.
+   *
+   * @param string $data
+   *   A string containing the contents of the file.
+   * @param \Drupal\user\UserInterface $user
+   *   The user of the file owner.
+   *
+   * @return \Drupal\file\FileInterface
+   *   A file object, or FALSE on error.
+   */
+  protected function createTemporaryFile($data, ?UserInterface $user = NULL) {
+    /** @var \Drupal\file\FileRepositoryInterface $file_repository */
+    $file_repository = \Drupal::service('file.repository');
+    $file = $file_repository->writeData($data, "public://");
+
+    if ($file) {
+      if ($user) {
+        $file->setOwner($user);
+      }
+      else {
+        $file->setOwner($this->adminUser);
+      }
+      // Change the file status to be temporary.
+      $file->setTemporary();
+      // Save the changes.
+      $file->save();
+    }
+
+    return $file;
+  }
+
+  /**
+   * Tests upload and remove buttons for a single-valued File field.
+   */
+  public function testSingleValuedWidget(): void {
+    $node_storage = $this->container->get('entity_type.manager')->getStorage('node');
+    $type_name = 'article';
+    $field_name = $this->randomMachineName();
+    $this->createFileField($field_name, 'node', $type_name);
+
+    $test_file = $this->getTestFile('text');
+
+    // Create a new node with the uploaded file and ensure it got uploaded
+    // successfully.
+    $nid = $this->uploadNodeFile($test_file, $field_name, $type_name);
+    $node = $node_storage->loadUnchanged($nid);
+    $node_file = File::load($node->{$field_name}->target_id);
+    $this->assertFileExists($node_file->getFileUri());
+
+    // Ensure the file can be downloaded.
+    $this->drupalGet($node_file->createFileUrl());
+    $this->assertSession()->statusCodeEquals(200);
+
+    // Ensure the edit page has a remove button instead of an upload button.
+    $this->drupalGet("node/$nid/edit");
+    $this->assertSession()->buttonNotExists('Upload');
+    $this->assertSession()->buttonExists('Remove');
+    $this->submitForm([], 'Remove');
+
+    // Ensure the page now has an upload button instead of a remove button.
+    $this->assertSession()->buttonNotExists('Remove');
+    $this->assertSession()->buttonExists('Upload');
+    // Test label has correct 'for' attribute.
+    $input = $this->assertSession()->fieldExists("files[{$field_name}_0]");
+    $this->assertSession()->elementExists('xpath', '//label[@for="' . $input->getAttribute('id') . '"]');
+
+    // Save the node and ensure it does not have the file.
+    $this->submitForm([], 'Save');
+    $node = $node_storage->loadUnchanged($nid);
+    $this->assertEmpty($node->{$field_name}->target_id, 'File was successfully removed from the node.');
+  }
+
+  /**
+   * Tests upload and remove buttons for multiple multi-valued File fields.
+   */
+  public function testMultiValuedWidget(): void {
+    $node_storage = $this->container->get('entity_type.manager')->getStorage('node');
+    $type_name = 'article';
+    // Use explicit names instead of random names for those fields, because of a
+    // bug in submitForm() with multiple file uploads in one form, where the
+    // order of uploads depends on the order in which the upload elements are
+    // added to the $form (which, in the current implementation of
+    // FileStorage::listAll(), comes down to the alphabetical order on field
+    // names).
+    $field_name = 'test_file_field_1';
+    $field_name2 = 'test_file_field_2';
+    $cardinality = 3;
+    $this->createFileField($field_name, 'node', $type_name, ['cardinality' => $cardinality]);
+    $this->createFileField($field_name2, 'node', $type_name, ['cardinality' => $cardinality]);
+
+    $test_file = $this->getTestFile('text');
+
+    // Visit the node creation form, and upload 3 files for each field. Since
+    // the field has cardinality of 3, ensure the "Upload" button is displayed
+    // until after the 3rd file, and after that, isn't displayed. Because
+    // the last button with a given name is triggered by default, upload to the
+    // second field first.
+    $this->drupalGet("node/add/$type_name");
+    foreach ([$field_name2, $field_name] as $each_field_name) {
+      for ($delta = 0; $delta < 3; $delta++) {
+        $edit = ['files[' . $each_field_name . '_' . $delta . '][]' => \Drupal::service('file_system')->realpath($test_file->getFileUri())];
+        // If the Upload button doesn't exist, submitForm() will
+        // automatically fail with an assertion message.
+        $this->submitForm($edit, 'Upload');
+      }
+    }
+    $this->assertSession()->buttonNotExists('Upload');
+
+    $num_expected_remove_buttons = 6;
+
+    foreach ([$field_name, $field_name2] as $current_field_name) {
+      // How many uploaded files for the current field are remaining.
+      $remaining = 3;
+      // Test clicking each "Remove" button. For extra robustness, test them out
+      // of sequential order. They are 0-indexed, and get renumbered after each
+      // iteration, so array(1, 1, 0) means:
+      // - First remove the 2nd file.
+      // - Then remove what is then the 2nd file (was originally the 3rd file).
+      // - Then remove the first file.
+      foreach ([1, 1, 0] as $delta) {
+        // Ensure we have the expected number of Remove buttons, and that they
+        // are numbered sequentially.
+        $buttons = $this->xpath('//input[@type="submit" and @value="Remove"]');
+        $this->assertCount($num_expected_remove_buttons, $buttons, "There are $num_expected_remove_buttons \"Remove\" buttons displayed.");
+        foreach ($buttons as $i => $button) {
+          $key = $i >= $remaining ? $i - $remaining : $i;
+          $check_field_name = $field_name2;
+          if ($current_field_name == $field_name && $i < $remaining) {
+            $check_field_name = $field_name;
+          }
+
+          $this->assertSame($check_field_name . '_' . $key . '_remove_button', $button->getAttribute('name'));
+        }
+
+        // "Click" the remove button (emulating either a nojs or js submission).
+        $button_name = $current_field_name . '_' . $delta . '_remove_button';
+        $this->getSession()->getPage()->findButton($button_name)->press();
+        $num_expected_remove_buttons--;
+        $remaining--;
+
+        // Ensure an "Upload" button for the current field is displayed with the
+        // correct name.
+        $upload_button_name = $current_field_name . '_' . $remaining . '_upload_button';
+        $button = $this->assertSession()->buttonExists($upload_button_name);
+        $this->assertSame('Upload', $button->getValue());
+
+        // Ensure only at most one button per field is displayed.
+        $expected = $current_field_name == $field_name ? 1 : 2;
+        $this->assertSession()->elementsCount('xpath', '//input[@type="submit" and @value="Upload"]', $expected);
+      }
+    }
+
+    // Ensure the page now has no Remove buttons.
+    $this->assertSession()->buttonNotExists('Remove');
+
+    // Save the node and ensure it does not have any files.
+    $this->submitForm(['title[0][value]' => $this->randomMachineName()], 'Save');
+    preg_match('/node\/([0-9])/', $this->getUrl(), $matches);
+    $nid = $matches[1];
+    $node = $node_storage->loadUnchanged($nid);
+    $this->assertEmpty($node->{$field_name}->target_id, 'Node was successfully saved without any files.');
+
+    // Try to upload more files than allowed on revision.
+    $upload_files_node_revision = [$test_file, $test_file, $test_file, $test_file];
+    foreach ($upload_files_node_revision as $i => $file) {
+      $edit['files[test_file_field_1_0][' . $i . ']'] = \Drupal::service('file_system')->realpath($test_file->getFileUri());
+    }
+
+    // @todo Replace after https://www.drupal.org/project/drupal/issues/2917885
+    $this->drupalGet('node/' . $node->id() . '/edit');
+    $this->assertSession()->fieldExists('files[test_file_field_1_0][]');
+    $submit_xpath = $this->assertSession()->buttonExists('Save')->getXpath();
+    $client = $this->getSession()->getDriver()->getClient();
+    $form = $client->getCrawler()->filterXPath($submit_xpath)->form();
+    $client->request($form->getMethod(), $form->getUri(), $form->getPhpValues(), $edit);
+
+    $node = $node_storage->loadUnchanged($nid);
+    $this->assertCount($cardinality, $node->{$field_name}, 'More files than allowed could not be saved to node.');
+
+    $upload_files_node_creation = [$test_file, $test_file];
+    // Try to upload multiple files, but fewer than the maximum.
+    $nid = $this->uploadNodeFiles($upload_files_node_creation, $field_name, $type_name, TRUE, []);
+    $node = $node_storage->loadUnchanged($nid);
+    $this->assertSameSize($upload_files_node_creation, $node->{$field_name}, 'Node was successfully saved with multiple files.');
+
+    // Try to upload exactly the allowed number of files on revision.
+    $this->uploadNodeFile($test_file, $field_name, $node->id(), 1);
+    $node = $node_storage->loadUnchanged($nid);
+    $this->assertCount($cardinality, $node->{$field_name}, 'Node was successfully revised to maximum number of files.');
+
+    // Try to upload exactly the allowed number of files, new node.
+    $upload_files = [$test_file, $test_file, $test_file];
+    $nid = $this->uploadNodeFiles($upload_files, $field_name, $type_name, TRUE, []);
+    $node = $node_storage->loadUnchanged($nid);
+    $this->assertCount($cardinality, $node->{$field_name}, 'Node was successfully saved with maximum number of files.');
+  }
+
+  /**
+   * Tests a file field with a "Private files" upload destination setting.
+   */
+  public function testPrivateFileSetting(): void {
+    $node_storage = $this->container->get('entity_type.manager')->getStorage('node');
+    // Grant the admin user required permissions.
+    user_role_grant_permissions($this->adminUser->roles[0]->target_id, ['administer node fields']);
+
+    $type_name = 'article';
+    $field_name = $this->randomMachineName();
+    $this->createFileField($field_name, 'node', $type_name);
+    $field = FieldConfig::loadByName('node', $type_name, $field_name);
+    $field_id = $field->id();
+
+    $test_file = $this->getTestFile('text');
+
+    // Change the field setting to make its files private, and upload a file.
+    $edit = ['field_storage[subform][settings][uri_scheme]' => 'private'];
+    $this->drupalGet("admin/structure/types/manage/{$type_name}/fields/{$field_id}");
+    $this->submitForm($edit, 'Save');
+    $nid = $this->uploadNodeFile($test_file, $field_name, $type_name);
+    $node = $node_storage->loadUnchanged($nid);
+    $node_file = File::load($node->{$field_name}->target_id);
+    $this->assertFileExists($node_file->getFileUri());
+
+    // Ensure the private file is available to the user who uploaded it.
+    $this->drupalGet($node_file->createFileUrl());
+    $this->assertSession()->statusCodeEquals(200);
+
+    // Ensure we can't change 'uri_scheme' field settings while there are some
+    // entities with uploaded files.
+    $this->drupalGet("admin/structure/types/manage/$type_name/fields/$field_id");
+    $this->assertSession()->fieldDisabled("edit-field-storage-subform-settings-uri-scheme-public");
+
+    // Delete node and confirm that setting could be changed.
+    $node->delete();
+    $this->drupalGet("admin/structure/types/manage/$type_name/fields/$field_id");
+    $this->assertSession()->fieldEnabled("edit-field-storage-subform-settings-uri-scheme-public");
+  }
+
+  /**
+   * Tests that download restrictions on private files work on comments.
+   */
+  public function testPrivateFileComment(): void {
+    $user = $this->drupalCreateUser(['access comments']);
+
+    // Grant the admin user required comment permissions.
+    $roles = $this->adminUser->getRoles();
+    user_role_grant_permissions($roles[1], ['administer comment fields', 'administer comments']);
+
+    // Revoke access comments permission from anon user, grant post to
+    // authenticated.
+    user_role_revoke_permissions(RoleInterface::ANONYMOUS_ID, ['access comments']);
+    user_role_grant_permissions(RoleInterface::AUTHENTICATED_ID, ['post comments', 'skip comment approval']);
+
+    // Create a new field.
+    $this->addDefaultCommentField('node', 'article');
+
+    $name = $this->randomMachineName();
+    $label = $this->randomMachineName();
+    $storage_edit = ['settings[uri_scheme]' => 'private'];
+    $this->fieldUIAddNewField('admin/structure/comment/manage/comment', $name, $label, 'file', $storage_edit);
+
+    // Manually clear cache on the tester side.
+    \Drupal::service('entity_field.manager')->clearCachedFieldDefinitions();
+
+    // Create node.
+    $edit = [
+      'title[0][value]' => $this->randomMachineName(),
+    ];
+    $this->drupalGet('node/add/article');
+    $this->submitForm($edit, 'Save');
+    $node = $this->drupalGetNodeByTitle($edit['title[0][value]']);
+
+    // Add a comment with a file.
+    $text_file = $this->getTestFile('text');
+    $edit = [
+      'files[field_' . $name . '_' . 0 . ']' => \Drupal::service('file_system')->realpath($text_file->getFileUri()),
+      'comment_body[0][value]' => $comment_body = $this->randomMachineName(),
+    ];
+    $this->drupalGet('node/' . $node->id());
+    $this->submitForm($edit, 'Save');
+
+    // Get the comment ID.
+    preg_match('/comment-([0-9]+)/', $this->getUrl(), $matches);
+    $cid = $matches[1];
+
+    // Log in as normal user.
+    $this->drupalLogin($user);
+
+    $comment = Comment::load($cid);
+    $comment_file = $comment->{'field_' . $name}->entity;
+    $this->assertFileExists($comment_file->getFileUri());
+    // Test authenticated file download.
+    $url = $comment_file->createFileUrl();
+    $this->assertNotNull($url, 'Confirmed that the URL is valid');
+    $this->drupalGet($comment_file->createFileUrl());
+    $this->assertSession()->statusCodeEquals(200);
+
+    // Ensure that the anonymous user cannot download the file.
+    $this->drupalLogout();
+    $this->drupalGet($comment_file->createFileUrl());
+    $this->assertSession()->statusCodeEquals(403);
+
+    // Unpublishes node.
+    $this->drupalLogin($this->adminUser);
+    $edit = ['status[value]' => FALSE];
+    $this->drupalGet('node/' . $node->id() . '/edit');
+    $this->submitForm($edit, 'Save');
+
+    // Ensures normal user can no longer download the file.
+    $this->drupalLogin($user);
+    $this->drupalGet($comment_file->createFileUrl());
+    $this->assertSession()->statusCodeEquals(403);
+  }
+
+  /**
+   * Tests validation with the Upload button.
+   */
+  public function testWidgetValidation(): void {
+    $type_name = 'article';
+    $field_name = $this->randomMachineName();
+    $this->createFileField($field_name, 'node', $type_name);
+    $this->updateFileField($field_name, $type_name, ['file_extensions' => 'txt']);
+
+    $type = 'nojs';
+    // Create node and prepare files for upload.
+    $node = $this->drupalCreateNode(['type' => 'article']);
+    $nid = $node->id();
+    $this->drupalGet("node/$nid/edit");
+    $test_file_text = $this->getTestFile('text');
+    $test_file_image = $this->getTestFile('image');
+    $name = 'files[' . $field_name . '_0]';
+
+    // Upload file with incorrect extension, check for validation error.
+    $edit[$name] = \Drupal::service('file_system')->realpath($test_file_image->getFileUri());
+    $this->submitForm($edit, 'Upload');
+
+    $this->assertSession()->pageTextContains("Only files with the following extensions are allowed: txt.");
+
+    // Upload file with correct extension, check that error message is removed.
+    $edit[$name] = \Drupal::service('file_system')->realpath($test_file_text->getFileUri());
+    $this->submitForm($edit, 'Upload');
+    $this->assertSession()->pageTextNotContains("Only files with the following extensions are allowed: txt.");
+  }
+
+  /**
+   * Tests file widget element.
+   */
+  public function testWidgetElement(): void {
+    $field_name = $this->randomMachineName();
+    $html_name = str_replace('_', '-', $field_name);
+    $this->createFileField($field_name, 'node', 'article', ['cardinality' => FieldStorageConfig::CARDINALITY_UNLIMITED]);
+    $file = $this->getTestFile('text');
+    $xpath = "//details[@data-drupal-selector='edit-$html_name']/table";
+
+    $this->drupalGet('node/add/article');
+
+    // If the field has no item, the table should not be visible.
+    $this->assertSession()->elementNotExists('xpath', $xpath);
+
+    // Upload a file.
+    $edit['files[' . $field_name . '_0][]'] = $this->container->get('file_system')->realpath($file->getFileUri());
+    $this->submitForm($edit, "{$field_name}_0_upload_button");
+
+    // If the field has at least one item, the table should be visible.
+    $this->assertSession()->elementsCount('xpath', $xpath, 1);
+
+    // Test for AJAX error when using progress bar on file field widget.
+    $http_client = $this->getHttpClient();
+    $key = $this->randomMachineName();
+    $post_request = $http_client->request('POST', $this->buildUrl('file/progress/' . $key), [
+      'headers' => [
+        'Accept' => 'application/json',
+        'Content-Type' => 'application/x-www-form-urlencoded',
+      ],
+      'http_errors' => FALSE,
+    ]);
+    $this->assertNotEquals(500, $post_request->getStatusCode());
+    $body = Json::decode($post_request->getBody());
+    $this->assertStringContainsString('Starting upload...', $body['message']);
+  }
+
+  /**
+   * Tests exploiting the temporary file removal of another user using fid.
+   */
+  public function testTemporaryFileRemovalExploit(): void {
+    // Create a victim user.
+    $victim_user = $this->drupalCreateUser();
+
+    // Create an attacker user.
+    $attacker_user = $this->drupalCreateUser([
+      'access content',
+      'create article content',
+      'edit any article content',
+    ]);
+
+    // Log in as the attacker user.
+    $this->drupalLogin($attacker_user);
+
+    // Perform tests using the newly created users.
+    $this->doTestTemporaryFileRemovalExploit($victim_user, $attacker_user);
+  }
+
+  /**
+   * Tests exploiting the temporary file removal for anonymous users using fid.
+   */
+  public function testTemporaryFileRemovalExploitAnonymous(): void {
+    // Set up an anonymous victim user.
+    $victim_user = User::getAnonymousUser();
+
+    // Set up an anonymous attacker user.
+    $attacker_user = User::getAnonymousUser();
+
+    // Set up permissions for anonymous attacker user.
+    user_role_change_permissions(RoleInterface::ANONYMOUS_ID, [
+      'access content' => TRUE,
+      'create article content' => TRUE,
+      'edit any article content' => TRUE,
+    ]);
+
+    // Log out so as to be the anonymous attacker user.
+    $this->drupalLogout();
+
+    // Perform tests using the newly set up anonymous users.
+    $this->doTestTemporaryFileRemovalExploit($victim_user, $attacker_user);
+  }
+
+  /**
+   * Tests maximum upload file size validation.
+   */
+  public function testMaximumUploadFileSizeValidation(): void {
+    // Grant the admin user required permissions.
+    user_role_grant_permissions($this->adminUser->roles[0]->target_id, ['administer node fields']);
+
+    $type_name = 'article';
+    $field_name = $this->randomMachineName();
+    $this->createFileField($field_name, 'node', $type_name);
+    /** @var \Drupal\Field\FieldConfigInterface $field */
+    $field = FieldConfig::loadByName('node', $type_name, $field_name);
+    $field_id = $field->id();
+    $this->drupalGet("admin/structure/types/manage/$type_name/fields/$field_id");
+
+    // Tests that form validation trims the user input.
+    $edit = ['settings[max_filesize]' => ' 5.1 megabytes '];
+    $this->submitForm($edit, 'Save settings');
+    $this->assertSession()->pageTextContains('Saved ' . $field_name . ' configuration.');
+
+    // Reload the field config to check for the saved value.
+    /** @var \Drupal\Field\FieldConfigInterface $field */
+    $field = FieldConfig::loadByName('node', $type_name, $field_name);
+    $settings = $field->getSettings();
+    $this->assertEquals('5.1 megabytes', $settings['max_filesize'], 'The max filesize value had been trimmed on save.');
+  }
+
+  /**
+   * Tests configuring file field's allowed file extensions setting.
+   */
+  public function testFileExtensionsSetting(): void {
+    // Grant the admin user required permissions.
+    user_role_grant_permissions($this->adminUser->roles[0]->target_id, ['administer node fields']);
+
+    $type_name = 'article';
+    $field_name = $this->randomMachineName();
+    $this->createFileField($field_name, 'node', $type_name);
+    $field = FieldConfig::loadByName('node', $type_name, $field_name);
+    $field_id = $field->id();
+
+    // By default allowing .php files without .txt is not permitted.
+    $this->drupalGet("admin/structure/types/manage/$type_name/fields/$field_id");
+    $edit = ['settings[file_extensions]' => 'jpg php'];
+    $this->submitForm($edit, 'Save settings');
+    $this->assertSession()->pageTextContains('Add txt to the list of allowed extensions to securely upload files with a php extension. The txt extension will then be added automatically.');
+
+    // Test allowing .php and .txt.
+    $edit = ['settings[file_extensions]' => 'jpg php txt'];
+    $this->submitForm($edit, 'Save settings');
+    $this->assertSession()->pageTextContains('Saved ' . $field_name . ' configuration.');
+
+    // If the system is configured to allow insecure uploads, .txt is not
+    // required when allowing .php.
+    $this->config('system.file')->set('allow_insecure_uploads', TRUE)->save();
+    $this->drupalGet("admin/structure/types/manage/$type_name/fields/$field_id");
+    $edit = ['settings[file_extensions]' => 'jpg php'];
+    $this->submitForm($edit, 'Save settings');
+    $this->assertSession()->pageTextContains('Saved ' . $field_name . ' configuration.');
+
+    // Check that a file extension with an underscore can be configured.
+    $edit = [
+      'settings[file_extensions]' => 'x_t x.t xt x_y_t',
+    ];
+    $this->drupalGet("admin/structure/types/manage/$type_name/fields/$field_id");
+    $this->submitForm($edit, 'Save settings');
+    $field = FieldConfig::loadByName('node', $type_name, $field_name);
+    $this->assertEquals('x_t x.t xt x_y_t', $field->getSetting('file_extensions'));
+
+    // Check that a file field with an invalid value in allowed extensions
+    // property throws an error message.
+    $invalid_extensions = ['x_.t', 'x._t', 'xt_', 'x__t', '_xt'];
+    foreach ($invalid_extensions as $value) {
+      $edit = [
+        'settings[file_extensions]' => $value,
+      ];
+      $this->drupalGet("admin/structure/types/manage/$type_name/fields/$field_id");
+      $this->submitForm($edit, 'Save settings');
+      $this->assertSession()->pageTextContains("The list of allowed extensions is not valid. Allowed characters are a-z, 0-9, '.', and '_'. The first and last characters cannot be '.' or '_', and these two characters cannot appear next to each other. Separate extensions with a comma or space.");
+    }
+  }
+
+  /**
+   * Helper for testing exploiting the temporary file removal using fid.
+   *
+   * @param \Drupal\user\UserInterface $victim_user
+   *   The victim user.
+   * @param \Drupal\user\UserInterface $attacker_user
+   *   The attacker user.
+   */
+  protected function doTestTemporaryFileRemovalExploit(UserInterface $victim_user, UserInterface $attacker_user) {
+    $type_name = 'article';
+    $field_name = 'test_file_field';
+    $this->createFileField($field_name, 'node', $type_name);
+
+    $test_file = $this->getTestFile('text');
+    $type = 'no-js';
+    // Create a temporary file owned by the victim user. This will be as if
+    // they had uploaded the file, but not saved the node they were editing
+    // or creating.
+    $victim_tmp_file = $this->createTemporaryFile('some text', $victim_user);
+    $victim_tmp_file = File::load($victim_tmp_file->id());
+    $this->assertTrue($victim_tmp_file->isTemporary(), 'New file saved to disk is temporary.');
+    $this->assertNotEmpty($victim_tmp_file->id(), 'New file has an fid.');
+    $this->assertEquals($victim_user->id(), $victim_tmp_file->getOwnerId(), 'New file belongs to the victim.');
+
+    // Have attacker create a new node with a different uploaded file and
+    // ensure it got uploaded successfully.
+    $edit = [
+      'title[0][value]' => $type . '-title',
+    ];
+
+    // Attach a file to a node.
+    $edit['files[' . $field_name . '_0]'] = $this->container->get('file_system')->realpath($test_file->getFileUri());
+    $this->drupalGet(Url::fromRoute('node.add', ['node_type' => $type_name]));
+    $this->submitForm($edit, 'Save');
+    $node = $this->drupalGetNodeByTitle($edit['title[0][value]']);
+
+    /** @var \Drupal\file\FileInterface $node_file */
+    $node_file = File::load($node->{$field_name}->target_id);
+    $this->assertFileExists($node_file->getFileUri());
+    $this->assertEquals($attacker_user->id(), $node_file->getOwnerId(), 'New file belongs to the attacker.');
+
+    // Ensure the file can be downloaded.
+    $this->drupalGet($node_file->createFileUrl());
+    $this->assertSession()->statusCodeEquals(200);
+
+    // "Click" the remove button (emulating either a nojs or js submission).
+    // In this POST request, the attacker "guesses" the fid of the victim's
+    // temporary file and uses that to remove this file.
+    $this->drupalGet($node->toUrl('edit-form'));
+
+    $file_id_field = $this->assertSession()->hiddenFieldExists($field_name . '[0][fids]');
+    $file_id_field->setValue((string) $victim_tmp_file->id());
+    $this->submitForm([], 'Remove');
+
+    // The victim's temporary file should not be removed by the attacker's
+    // POST request.
+    $this->assertFileExists($victim_tmp_file->getFileUri());
+  }
+
+}

core/modules/file/tests/src/Functional/FileListingTest.php

@@ -0,0 +1,284 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+use Drupal\node\Entity\Node;
+use Drupal\file\Entity\File;
+use Drupal\entity_test\Entity\EntityTestConstraints;
+use Drupal\user\Entity\Role;
+
+/**
+ * Tests file listing page functionality.
+ *
+ * @group file
+ */
+class FileListingTest extends FileFieldTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  protected static $modules = ['views', 'file', 'image', 'entity_test'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * An authenticated user.
+   *
+   * @var \Drupal\user\UserInterface
+   */
+  protected $baseUser;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+
+    // This test expects unused managed files to be marked as a temporary file.
+    $this->config('file.settings')
+      ->set('make_unused_managed_files_temporary', TRUE)
+      ->save();
+
+    $this->adminUser = $this->drupalCreateUser([
+      'access files overview',
+      'bypass node access',
+      'delete any file',
+    ]);
+    $this->baseUser = $this->drupalCreateUser();
+    $this->createFileField('file', 'node', 'article', [], ['file_extensions' => 'txt png']);
+  }
+
+  /**
+   * Calculates total count of usages for a file.
+   *
+   * @param array $usage
+   *   Array of file usage information as returned from file_usage subsystem.
+   *
+   * @return int
+   *   Total usage count.
+   */
+  protected function sumUsages($usage) {
+    $count = 0;
+    foreach ($usage as $module) {
+      foreach ($module as $entity_type) {
+        foreach ($entity_type as $entity) {
+          $count += $entity;
+        }
+      }
+    }
+
+    return $count;
+  }
+
+  /**
+   * Tests file overview with different user permissions.
+   */
+  public function testFileListingPages(): void {
+    $file_usage = $this->container->get('file.usage');
+    // Users without sufficient permissions should not see file listing.
+    $this->drupalLogin($this->baseUser);
+    $this->drupalGet('admin/content/files');
+    $this->assertSession()->statusCodeEquals(403);
+
+    // Log in with user with right permissions and test listing.
+    $this->drupalLogin($this->adminUser);
+
+    for ($i = 0; $i < 5; $i++) {
+      $nodes[] = $this->drupalCreateNode(['type' => 'article']);
+    }
+
+    $this->drupalGet('admin/content/files');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains('No files available.');
+    $this->drupalGet('admin/content/files');
+    $this->assertSession()->statusCodeEquals(200);
+
+    // Create a file with no usage.
+    $file = $this->createFile();
+
+    $this->drupalGet('admin/content/files/usage/' . $file->id());
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->titleEquals('File usage information for ' . $file->getFilename() . ' | Drupal');
+
+    foreach ($nodes as &$node) {
+      $this->drupalGet('node/' . $node->id() . '/edit');
+      $file = $this->getTestFile('image');
+
+      $edit = [
+        'files[file_0]' => \Drupal::service('file_system')->realpath($file->getFileUri()),
+      ];
+      $this->submitForm($edit, 'Save');
+      $node = Node::load($node->id());
+    }
+
+    $this->drupalGet('admin/content/files');
+
+    foreach ($nodes as $node) {
+      $file = File::load($node->file->target_id);
+      $this->assertSession()->pageTextContains($file->getFilename());
+      $this->assertSession()->linkByHrefExists($file->createFileUrl());
+      $this->assertSession()->linkByHrefExists('admin/content/files/usage/' . $file->id());
+      $this->assertSession()->linkByHrefExists($file->toUrl('delete-form')->toString());
+    }
+    $this->assertSession()->elementTextNotContains('css', '.views-element-container table', 'Temporary');
+    $this->assertSession()->elementTextContains('css', '.views-element-container table', 'Permanent');
+
+    // Use one file two times and check usage information.
+    $orphaned_file = $nodes[1]->file->target_id;
+    $used_file = $nodes[0]->file->target_id;
+    $nodes[1]->file->target_id = $used_file;
+    $nodes[1]->save();
+
+    $this->drupalGet('admin/content/files');
+    $file = File::load($orphaned_file);
+    $usage = $this->sumUsages($file_usage->listUsage($file));
+    $this->assertSession()->responseContains('admin/content/files/usage/' . $file->id() . '">' . $usage);
+
+    $file = File::load($used_file);
+    $usage = $this->sumUsages($file_usage->listUsage($file));
+    $this->assertSession()->responseContains('admin/content/files/usage/' . $file->id() . '">' . $usage);
+
+    $this->assertSession()->elementsCount('xpath', "//td[contains(@class, 'views-field-status') and contains(text(), 'Temporary')]", 1);
+
+    // Test file usage page.
+    foreach ($nodes as $node) {
+      $file = File::load($node->file->target_id);
+      $usage = $file_usage->listUsage($file);
+      $this->drupalGet('admin/content/files/usage/' . $file->id());
+      $this->assertSession()->statusCodeEquals(200);
+      $this->assertSession()->pageTextContains($node->getTitle());
+      // Verify that registering entity type is found on usage page.
+      $this->assertSession()->pageTextContains('node');
+      // Verify that registering module is found on usage page.
+      $this->assertSession()->pageTextContains('file');
+      foreach ($usage as $module) {
+        foreach ($module as $entity_type) {
+          foreach ($entity_type as $entity) {
+            // Verify that usage count is found on usage page.
+            $this->assertSession()->pageTextContains($entity);
+          }
+        }
+      }
+      $this->assertSession()->linkByHrefExists('node/' . $node->id(), 0, 'Link to registering entity found on usage page.');
+    }
+
+    // Log in as another user that has access to the file list but cannot delete
+    // files.
+    $role_id = $this->drupalCreateRole([
+      'access files overview',
+      'bypass node access',
+    ]);
+    $this->drupalLogin($this->drupalCreateUser(values: ['roles' => [$role_id]]));
+
+    $this->drupalGet('admin/content/files');
+    foreach ($nodes as $node) {
+      $file = File::load($node->file->target_id);
+      $this->assertSession()->pageTextContains($file->getFilename());
+      $this->assertSession()->linkByHrefExists($file->createFileUrl());
+      $this->assertSession()->linkByHrefExists('admin/content/files/usage/' . $file->id());
+      $this->assertSession()->linkByHrefNotExists($file->toUrl('delete-form')->toString());
+    }
+    // Give the user's role permission to delete files.
+    Role::load($role_id)->grantPermission('delete any file')->save();
+    $this->drupalGet('admin/content/files');
+    foreach ($nodes as $node) {
+      $file = File::load($node->file->target_id);
+      $this->assertSession()->pageTextContains($file->getFilename());
+      $this->assertSession()->linkByHrefExists($file->createFileUrl());
+      $this->assertSession()->linkByHrefExists('admin/content/files/usage/' . $file->id());
+      $this->assertSession()->linkByHrefExists($file->toUrl('delete-form')->toString());
+    }
+    // Load the page in a definite order.
+    $this->drupalGet('admin/content/files', ['query' => ['order' => 'filename', 'sort' => 'asc']]);
+    $this->clickLink('Delete');
+    $file_uri = File::load(1)->getFileUri();
+    $this->assertSession()->addressMatches('#file/1/delete$#');
+    $this->assertSession()->pageTextContains('Are you sure you want to delete the file druplicon.txt?');
+    $this->assertFileExists($file_uri);
+    $this->assertSession()->buttonExists('Delete')->press();
+    $this->assertSession()->pageTextContains('The file druplicon.txt has been deleted.');
+    $this->assertFileDoesNotExist($file_uri);
+  }
+
+  /**
+   * Tests file listing usage page for entities with no canonical link template.
+   */
+  public function testFileListingUsageNoLink(): void {
+    // Login with user with right permissions and test listing.
+    $this->drupalLogin($this->adminUser);
+
+    // Create a bundle and attach a File field to the bundle.
+    $bundle = $this->randomMachineName();
+    entity_test_create_bundle($bundle, NULL, 'entity_test_constraints');
+    $this->createFileField('field_test_file', 'entity_test_constraints', $bundle, [], ['file_extensions' => 'txt png']);
+
+    // Create file to attach to entity.
+    $file = File::create([
+      'filename' => 'druplicon.txt',
+      'uri' => 'public://druplicon.txt',
+      'filemime' => 'text/plain',
+    ]);
+    $file->setPermanent();
+    file_put_contents($file->getFileUri(), 'hello world');
+    $file->save();
+
+    // Create entity and attach the created file.
+    $entity_name = $this->randomMachineName();
+    $entity = EntityTestConstraints::create([
+      'uid' => 1,
+      'name' => $entity_name,
+      'type' => $bundle,
+      'field_test_file' => [
+        'target_id' => $file->id(),
+      ],
+    ]);
+    $entity->save();
+
+    // Create node entity and attach the created file.
+    $node = $this->drupalCreateNode(['type' => 'article', 'file' => $file]);
+    $node->save();
+
+    // Load the file usage page for the created and attached file.
+    $this->drupalGet('admin/content/files/usage/' . $file->id());
+
+    $this->assertSession()->statusCodeEquals(200);
+    // Entity name should be displayed, but not linked if Entity::toUrl
+    // throws an exception
+    $this->assertSession()->pageTextContains($entity_name);
+    $this->assertSession()->linkNotExists($entity_name, 'Linked entity name not added to file usage listing.');
+    $this->assertSession()->linkExists($node->getTitle());
+  }
+
+  /**
+   * Creates and saves a test file.
+   *
+   * @return \Drupal\Core\Entity\EntityInterface
+   *   A file entity.
+   */
+  protected function createFile() {
+    // Create a new file entity.
+    $file = File::create([
+      'uid' => 1,
+      'filename' => 'druplicon.txt',
+      'uri' => 'public://druplicon.txt',
+      'filemime' => 'text/plain',
+      'created' => 1,
+      'changed' => 1,
+    ]);
+    $file->setPermanent();
+    file_put_contents($file->getFileUri(), 'hello world');
+
+    // Save it, inserting a new record.
+    $file->save();
+
+    return $file;
+  }
+
+}

core/modules/file/tests/src/Functional/FileManagedFileElementTest.php

@@ -0,0 +1,258 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+use Drupal\file\Entity\File;
+
+/**
+ * Tests the 'managed_file' element type.
+ *
+ * @group file
+ * @group #slow
+ * @todo Create a FileTestBase class and move FileFieldTestBase methods
+ *   that aren't related to fields into it.
+ */
+class FileManagedFileElementTest extends FileFieldTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * Tests the managed_file element type.
+   */
+  public function testManagedFile(): void {
+    // Check that $element['#size'] is passed to the child upload element.
+    $this->drupalGet('file/test');
+    $field = $this->assertSession()->fieldExists("files[nested_file]");
+    $this->assertEquals(13, $field->getAttribute('size'));
+
+    // Perform the tests with all permutations of $form['#tree'],
+    // $element['#extended'], and $element['#multiple'].
+    $test_file = $this->getTestFile('text');
+    foreach ([0, 1] as $tree) {
+      foreach ([0, 1] as $extended) {
+        foreach ([0, 1] as $multiple) {
+          $path = 'file/test/' . $tree . '/' . $extended . '/' . $multiple;
+          $input_base_name = $tree ? 'nested_file' : 'file';
+          $file_field_name = $multiple ? 'files[' . $input_base_name . '][]' : 'files[' . $input_base_name . ']';
+
+          // Submit without a file.
+          $this->drupalGet($path);
+          $this->submitForm([], 'Save');
+          $this->assertSession()->pageTextContains("The file ids are .");
+
+          // Submit with a file, but with an invalid form token. Ensure the file
+          // was not saved.
+          $last_fid_prior = $this->getLastFileId();
+          $this->drupalGet($path);
+          $form_token_field = $this->assertSession()->hiddenFieldExists('form_token');
+          $form_token_field->setValue('invalid token');
+          $edit = [
+            $file_field_name => \Drupal::service('file_system')->realpath($test_file->getFileUri()),
+          ];
+          $this->submitForm($edit, 'Save');
+          $this->assertSession()->pageTextContains('The form has become outdated.');
+          $last_fid = $this->getLastFileId();
+          $this->assertEquals($last_fid_prior, $last_fid, 'File was not saved when uploaded with an invalid form token.');
+
+          // Submit a new file, without using the Upload button.
+          $last_fid_prior = $this->getLastFileId();
+          $edit = [$file_field_name => \Drupal::service('file_system')->realpath($test_file->getFileUri())];
+          $this->drupalGet($path);
+          $this->submitForm($edit, 'Save');
+          $last_fid = $this->getLastFileId();
+          $this->assertGreaterThan($last_fid_prior, $last_fid, 'New file got saved.');
+          $this->assertSession()->pageTextContains("The file ids are $last_fid.");
+
+          // Submit no new input, but with a default file.
+          $this->drupalGet($path . '/' . $last_fid);
+          $this->submitForm([], 'Save');
+          $this->assertSession()->pageTextContains("The file ids are $last_fid.");
+
+          // Upload, then Submit.
+          $last_fid_prior = $this->getLastFileId();
+          $this->drupalGet($path);
+          $edit = [$file_field_name => \Drupal::service('file_system')->realpath($test_file->getFileUri())];
+          $this->submitForm($edit, 'Upload');
+          $last_fid = $this->getLastFileId();
+          $this->assertGreaterThan($last_fid_prior, $last_fid, 'New file got uploaded.');
+          $this->submitForm([], 'Save');
+          $this->assertSession()->pageTextContains("The file ids are $last_fid.");
+
+          // Remove, then Submit.
+          $remove_button_title = $multiple ? 'Remove selected' : 'Remove';
+          $remove_edit = [];
+          if ($multiple) {
+            $selected_checkbox = ($tree ? 'nested[file]' : 'file') . '[file_' . $last_fid . '][selected]';
+            $remove_edit = [$selected_checkbox => '1'];
+          }
+          $this->drupalGet($path . '/' . $last_fid);
+          $this->submitForm($remove_edit, $remove_button_title);
+          $this->submitForm([], 'Save');
+          $this->assertSession()->pageTextContains("The file ids are .");
+
+          // Upload, then Remove, then Submit.
+          $this->drupalGet($path);
+          $edit = [$file_field_name => \Drupal::service('file_system')->realpath($test_file->getFileUri())];
+          $this->submitForm($edit, 'Upload');
+          $remove_edit = [];
+          if ($multiple) {
+            $selected_checkbox = ($tree ? 'nested[file]' : 'file') . '[file_' . $this->getLastFileId() . '][selected]';
+            $remove_edit = [$selected_checkbox => '1'];
+          }
+          $this->submitForm($remove_edit, $remove_button_title);
+
+          $this->submitForm([], 'Save');
+          $this->assertSession()->pageTextContains("The file ids are .");
+        }
+      }
+    }
+
+    // The multiple file upload has additional conditions that need checking.
+    $path = 'file/test/1/1/1';
+    $edit = ['files[nested_file][]' => \Drupal::service('file_system')->realpath($test_file->getFileUri())];
+    $fid_list = [];
+
+    $this->drupalGet($path);
+
+    // Add a single file to the upload field.
+    $this->submitForm($edit, 'Upload');
+    $fid_list[] = $this->getLastFileId();
+    $this->assertSession()->fieldExists("nested[file][file_{$fid_list[0]}][selected]");
+
+    // Add another file to the same upload field.
+    $this->submitForm($edit, 'Upload');
+    $fid_list[] = $this->getLastFileId();
+    $this->assertSession()->fieldExists("nested[file][file_{$fid_list[1]}][selected]");
+
+    // Save the entire form.
+    $this->submitForm([], 'Save');
+    // Check that two files are saved into a single multiple file element.
+    $this->assertSession()->pageTextContains("The file ids are " . implode(',', $fid_list) . ".");
+
+    // Delete only the first file.
+    $edit = [
+      'nested[file][file_' . $fid_list[0] . '][selected]' => '1',
+    ];
+    $this->drupalGet($path . '/' . implode(',', $fid_list));
+    $this->submitForm($edit, 'Remove selected');
+
+    // Check that the first file has been deleted but not the second.
+    $this->assertSession()->fieldNotExists("nested[file][file_{$fid_list[0]}][selected]");
+    $this->assertSession()->fieldExists("nested[file][file_{$fid_list[1]}][selected]");
+  }
+
+  /**
+   * Ensure that warning is shown if file on the field has been removed.
+   */
+  public function testManagedFileRemoved(): void {
+    $this->drupalGet('file/test/1/0/1');
+    $test_file = $this->getTestFile('text');
+    $file_field_name = 'files[nested_file][]';
+
+    $edit = [$file_field_name => \Drupal::service('file_system')->realpath($test_file->getFileUri())];
+    $this->submitForm($edit, 'Upload');
+
+    $fid = $this->getLastFileId();
+    $file = \Drupal::entityTypeManager()->getStorage('file')->load($fid);
+    $file->delete();
+
+    $this->submitForm($edit, 'Upload');
+    // We expect the title 'Managed <em>file & butter</em>' which got escaped
+    // via a t() call before.
+    $this->assertSession()->responseContains('The file referenced by the Managed <em>file &amp; butter</em> field does not exist.');
+  }
+
+  /**
+   * Tests file names have leading . removed.
+   */
+  public function testFileNameTrim(): void {
+    file_put_contents('public://.leading-period.txt', $this->randomString(32));
+    $last_fid_prior = $this->getLastFileId();
+    $this->drupalGet('file/test/0/0/0');
+    $this->submitForm(['files[file]' => \Drupal::service('file_system')->realpath('public://.leading-period.txt')], 'Save');
+    $next_fid = $this->getLastFileId();
+    $this->assertGreaterThan($last_fid_prior, $next_fid);
+    $file = File::load($next_fid);
+    $this->assertEquals('leading-period.txt', $file->getFilename());
+  }
+
+  /**
+   * Ensure a file entity can be saved when the file does not exist on disk.
+   */
+  public function testFileRemovedFromDisk(): void {
+    $this->drupalGet('file/test/1/0/1');
+    $test_file = $this->getTestFile('text');
+    $file_field_name = 'files[nested_file][]';
+
+    $edit = [$file_field_name => \Drupal::service('file_system')->realpath($test_file->getFileUri())];
+    $this->submitForm($edit, 'Upload');
+    $this->submitForm([], 'Save');
+
+    $fid = $this->getLastFileId();
+    /** @var \Drupal\file\FileInterface $file */
+    $file = $this->container->get('entity_type.manager')->getStorage('file')->load($fid);
+    $file->setPermanent();
+    $file->save();
+    $this->assertTrue(\Drupal::service('file_system')->delete($file->getFileUri()));
+    $file->save();
+    $this->assertTrue($file->isPermanent());
+    $file->delete();
+  }
+
+  /**
+   * Verify that unused permanent files can be used.
+   */
+  public function testUnusedPermanentFileValidation(): void {
+
+    // Create a permanent file without usages.
+    $file = $this->getTestFile('image');
+    $file->setPermanent();
+    $file->save();
+
+    // By default, unused files are no longer marked temporary, and it must be
+    // allowed to reference an unused file.
+    $this->drupalGet('file/test/1/0/1/' . $file->id());
+    $this->submitForm([], 'Save');
+    $this->assertSession()->pageTextNotContains('The file used in the Managed file & butter field may not be referenced.');
+    $this->assertSession()->pageTextContains('The file ids are ' . $file->id());
+
+    // Enable marking unused files as temporary, unused permanent files must not
+    // be referenced now.
+    $this->config('file.settings')
+      ->set('make_unused_managed_files_temporary', TRUE)
+      ->save();
+    $this->drupalGet('file/test/1/0/1/' . $file->id());
+    $this->submitForm([], 'Save');
+    $this->assertSession()->pageTextContains('The file used in the Managed file & butter field may not be referenced.');
+    $this->assertSession()->pageTextNotContains('The file ids are ' . $file->id());
+
+    // Make the file temporary, now using it is allowed.
+    $file->setTemporary();
+    $file->save();
+
+    $this->drupalGet('file/test/1/0/1/' . $file->id());
+    $this->submitForm([], 'Save');
+    $this->assertSession()->pageTextNotContains('The file used in the Managed file & butter field may not be referenced.');
+    $this->assertSession()->pageTextContains('The file ids are ' . $file->id());
+
+    // Make the file permanent again and add a usage from itself, referencing is
+    // still allowed.
+    $file->setPermanent();
+    $file->save();
+
+    /** @var \Drupal\file\FileUsage\FileUsageInterface $file_usage */
+    $file_usage = \Drupal::service('file.usage');
+    $file_usage->add($file, 'file', 'file', $file->id());
+
+    $this->drupalGet('file/test/1/0/1/' . $file->id());
+    $this->submitForm([], 'Save');
+    $this->assertSession()->pageTextNotContains('The file used in the Managed file & butter field may not be referenced.');
+    $this->assertSession()->pageTextContains('The file ids are ' . $file->id());
+  }
+
+}

core/modules/file/tests/src/Functional/FileManagedTestBase.php

@@ -0,0 +1,206 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+use Drupal\Component\Render\FormattableMarkup;
+use Drupal\file\Entity\File;
+use Drupal\file\FileInterface;
+use Drupal\Tests\BrowserTestBase;
+
+/**
+ * Provides a base class for testing files with the file_test module.
+ */
+abstract class FileManagedTestBase extends BrowserTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  protected static $modules = ['file_test', 'file'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    // Clear out any hook calls.
+    file_test_reset();
+  }
+
+  /**
+   * Asserts that the specified file hooks were called only once.
+   *
+   * @param string[] $expected
+   *   An array of strings containing with the hook name; for example, 'load',
+   *   'save', 'insert', etc.
+   */
+  public function assertFileHooksCalled($expected) {
+    \Drupal::state()->resetCache();
+
+    // Determine which hooks were called.
+    $actual = array_keys(array_filter(file_test_get_all_calls()));
+
+    // Determine if there were any expected that were not called.
+    $uncalled = array_diff($expected, $actual);
+    if (count($uncalled)) {
+      $this->assertTrue(FALSE, sprintf('Expected hooks %s to be called but %s was not called.', implode(', ', $expected), implode(', ', $uncalled)));
+    }
+    else {
+      $this->assertTrue(TRUE, sprintf('All the expected hooks were called: %s', empty($expected) ? '(none)' : implode(', ', $expected)));
+    }
+
+    // Determine if there were any unexpected calls.
+    $unexpected = array_diff($actual, $expected);
+    if (count($unexpected)) {
+      $this->assertTrue(FALSE, sprintf('Unexpected hooks were called: %s.', empty($unexpected) ? '(none)' : implode(', ', $unexpected)));
+    }
+    else {
+      $this->assertTrue(TRUE, 'No unexpected hooks were called.');
+    }
+  }
+
+  /**
+   * Assert that a hook_file_* hook was called a certain number of times.
+   *
+   * @param string $hook
+   *   String with the hook name; for instance, 'load', 'save', 'insert', etc.
+   * @param int $expected_count
+   *   Optional integer count.
+   * @param string|null $message
+   *   Optional translated string message.
+   */
+  public function assertFileHookCalled($hook, $expected_count = 1, $message = NULL) {
+    $actual_count = count(file_test_get_calls($hook));
+
+    if (!isset($message)) {
+      if ($actual_count == $expected_count) {
+        $message = new FormattableMarkup('hook_file_@name was called correctly.', ['@name' => $hook]);
+      }
+      elseif ($expected_count == 0) {
+        $message = \Drupal::translation()->formatPlural($actual_count, 'hook_file_@name was not expected to be called but was actually called once.', 'hook_file_@name was not expected to be called but was actually called @count times.', ['@name' => $hook, '@count' => $actual_count]);
+      }
+      else {
+        $message = new FormattableMarkup('hook_file_@name was expected to be called %expected times but was called %actual times.', ['@name' => $hook, '%expected' => $expected_count, '%actual' => $actual_count]);
+      }
+    }
+    $this->assertEquals($expected_count, $actual_count, $message);
+  }
+
+  /**
+   * Asserts that two files have the same values (except timestamp).
+   *
+   * @param \Drupal\file\FileInterface $before
+   *   File object to compare.
+   * @param \Drupal\file\FileInterface $after
+   *   File object to compare.
+   */
+  public function assertFileUnchanged(FileInterface $before, FileInterface $after) {
+    $this->assertEquals($before->id(), $after->id());
+    $this->assertEquals($before->getOwner()->id(), $after->getOwner()->id());
+    $this->assertEquals($before->getFilename(), $after->getFilename());
+    $this->assertEquals($before->getFileUri(), $after->getFileUri());
+    $this->assertEquals($before->getMimeType(), $after->getMimeType());
+    $this->assertEquals($before->getSize(), $after->getSize());
+    $this->assertEquals($before->isPermanent(), $after->isPermanent());
+  }
+
+  /**
+   * Asserts that two files are not the same by comparing the fid and filepath.
+   *
+   * @param \Drupal\file\FileInterface $file1
+   *   File object to compare.
+   * @param \Drupal\file\FileInterface $file2
+   *   File object to compare.
+   */
+  public function assertDifferentFile(FileInterface $file1, FileInterface $file2) {
+    $this->assertNotEquals($file1->id(), $file2->id());
+    $this->assertNotEquals($file1->getFileUri(), $file2->getFileUri());
+  }
+
+  /**
+   * Asserts that two files are the same by comparing the fid and filepath.
+   *
+   * @param \Drupal\file\FileInterface $file1
+   *   File object to compare.
+   * @param \Drupal\file\FileInterface $file2
+   *   File object to compare.
+   */
+  public function assertSameFile(FileInterface $file1, FileInterface $file2) {
+    $this->assertEquals($file1->id(), $file2->id());
+    $this->assertEquals($file1->getFileUri(), $file2->getFileUri());
+  }
+
+  /**
+   * Creates and saves a file, asserting that it was saved.
+   *
+   * @param string $filepath
+   *   Optional string specifying the file path. If none is provided then a
+   *   randomly named file will be created in the site's files directory.
+   * @param string $contents
+   *   Optional contents to save into the file. If a NULL value is provided an
+   *   arbitrary string will be used.
+   * @param string $scheme
+   *   Optional string indicating the stream scheme to use. Drupal core includes
+   *   public, private, and temporary. The public wrapper is the default.
+   *
+   * @return \Drupal\file\FileInterface
+   *   File entity.
+   */
+  public function createFile($filepath = NULL, $contents = NULL, $scheme = NULL) {
+    // Don't count hook invocations caused by creating the file.
+    \Drupal::state()->set('file_test.count_hook_invocations', FALSE);
+    $file = File::create([
+      'uri' => $this->createUri($filepath, $contents, $scheme),
+      'uid' => 1,
+    ]);
+    $file->save();
+    // Write the record directly rather than using the API so we don't invoke
+    // the hooks.
+    // Verify that the file was added to the database.
+    $this->assertGreaterThan(0, $file->id());
+
+    \Drupal::state()->set('file_test.count_hook_invocations', TRUE);
+    return $file;
+  }
+
+  /**
+   * Creates a file and returns its URI.
+   *
+   * @param string $filepath
+   *   Optional string specifying the file path. If none is provided then a
+   *   randomly named file will be created in the site's files directory.
+   * @param string $contents
+   *   Optional contents to save into the file. If a NULL value is provided an
+   *   arbitrary string will be used.
+   * @param string $scheme
+   *   Optional string indicating the stream scheme to use. Drupal core includes
+   *   public, private, and temporary. The public wrapper is the default.
+   *
+   * @return string
+   *   File URI.
+   */
+  public function createUri($filepath = NULL, $contents = NULL, $scheme = NULL) {
+    if (!isset($filepath)) {
+      // Prefix with non-latin characters to ensure that all file-related
+      // tests work with international filenames.
+      // cSpell:disable-next-line
+      $filepath = 'Файл для тестирования ' . $this->randomMachineName();
+    }
+    if (!isset($scheme)) {
+      $scheme = 'public';
+    }
+    $filepath = $scheme . '://' . $filepath;
+
+    if (!isset($contents)) {
+      $contents = "file_put_contents() doesn't seem to appreciate empty strings so let's put in some data.";
+    }
+
+    file_put_contents($filepath, $contents);
+    $this->assertFileExists($filepath);
+    return $filepath;
+  }
+
+}

core/modules/file/tests/src/Functional/FileOnTranslatedEntityTest.php

@@ -0,0 +1,249 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+use Drupal\file\Entity\File;
+use Drupal\Tests\content_translation\Traits\ContentTranslationTestTrait;
+
+// cspell:ignore Scarlett Johansson
+
+/**
+ * Uploads files to translated nodes.
+ *
+ * @group file
+ */
+class FileOnTranslatedEntityTest extends FileFieldTestBase {
+
+  use ContentTranslationTestTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['language', 'content_translation'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * The name of the file field used in the test.
+   *
+   * @var string
+   */
+  protected $fieldName;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+
+    // This test expects unused managed files to be marked as temporary a file.
+    $this->config('file.settings')
+      ->set('make_unused_managed_files_temporary', TRUE)
+      ->save();
+
+    // Create the "Basic page" node type.
+    // @todo Remove the disabling of new revision creation in
+    //   https://www.drupal.org/node/1239558.
+    $this->drupalCreateContentType(['type' => 'page', 'name' => 'Basic page', 'new_revision' => FALSE]);
+
+    // Create a file field on the "Basic page" node type.
+    $this->fieldName = $this->randomMachineName();
+    $this->createFileField($this->fieldName, 'node', 'page');
+
+    // Create and log in user.
+    $permissions = [
+      'access administration pages',
+      'administer content translation',
+      'administer content types',
+      'administer languages',
+      'create content translations',
+      'create page content',
+      'edit any page content',
+      'translate any entity',
+      'delete any page content',
+    ];
+    $admin_user = $this->drupalCreateUser($permissions);
+    $this->drupalLogin($admin_user);
+
+    // Add a second and third language.
+    static::createLanguageFromLangcode('fr');
+    static::createLanguageFromLangcode('nl');
+
+    // Enable translation for "Basic page" nodes.
+    static::enableContentTranslation('node', 'page');
+    static::setFieldTranslatable('node', 'page', $this->fieldName, TRUE);
+  }
+
+  /**
+   * Tests synced file fields on translated nodes.
+   */
+  public function testSyncedFiles(): void {
+    // Verify that the file field on the "Basic page" node type is translatable.
+    $definitions = \Drupal::service('entity_field.manager')->getFieldDefinitions('node', 'page');
+    $this->assertTrue($definitions[$this->fieldName]->isTranslatable(), 'Node file field is translatable.');
+
+    // Create a default language node.
+    $default_language_node = $this->drupalCreateNode(['type' => 'page', 'title' => 'Lost in translation']);
+
+    // Edit the node to upload a file.
+    $edit = [];
+    $name = 'files[' . $this->fieldName . '_0]';
+    $edit[$name] = \Drupal::service('file_system')->realpath($this->drupalGetTestFiles('text')[0]->uri);
+    $this->drupalGet('node/' . $default_language_node->id() . '/edit');
+    $this->submitForm($edit, 'Save');
+    $first_fid = $this->getLastFileId();
+
+    // Translate the node into French: remove the existing file.
+    $this->drupalGet('node/' . $default_language_node->id() . '/translations/add/en/fr');
+    $this->submitForm([], 'Remove');
+
+    // Upload a different file.
+    $edit = [];
+    $edit['title[0][value]'] = 'Bill Murray';
+    $name = 'files[' . $this->fieldName . '_0]';
+    $edit[$name] = \Drupal::service('file_system')->realpath($this->drupalGetTestFiles('text')[1]->uri);
+    $this->submitForm($edit, 'Save (this translation)');
+    // This inspects the HTML after the post of the translation, the file
+    // should be displayed on the original node.
+    $this->assertSession()->responseContains('file--mime-text-plain');
+    $second_fid = $this->getLastFileId();
+
+    \Drupal::entityTypeManager()->getStorage('file')->resetCache();
+
+    /** @var \Drupal\file\FileInterface $file */
+
+    // Ensure the file status of the first file permanent.
+    $file = File::load($first_fid);
+    $this->assertTrue($file->isPermanent());
+
+    // Ensure the file status of the second file is permanent.
+    $file = File::load($second_fid);
+    $this->assertTrue($file->isPermanent());
+
+    // Translate the node into dutch: remove the existing file.
+    $this->drupalGet('node/' . $default_language_node->id() . '/translations/add/en/nl');
+    $this->submitForm([], 'Remove');
+
+    // Upload a different file.
+    $edit = [];
+    $edit['title[0][value]'] = 'Scarlett Johansson';
+    $name = 'files[' . $this->fieldName . '_0]';
+    $edit[$name] = \Drupal::service('file_system')->realpath($this->drupalGetTestFiles('text')[2]->uri);
+    $this->submitForm($edit, 'Save (this translation)');
+    $third_fid = $this->getLastFileId();
+
+    \Drupal::entityTypeManager()->getStorage('file')->resetCache();
+
+    // Ensure the first file is untouched.
+    $file = File::load($first_fid);
+    $this->assertTrue($file->isPermanent(), 'First file still exists and is permanent.');
+    // This inspects the HTML after the post of the translation, the file
+    // should be displayed on the original node.
+    $this->assertSession()->responseContains('file--mime-text-plain');
+
+    // Ensure the file status of the second file is permanent.
+    $file = File::load($second_fid);
+    $this->assertTrue($file->isPermanent());
+
+    // Ensure the file status of the third file is permanent.
+    $file = File::load($third_fid);
+    $this->assertTrue($file->isPermanent());
+
+    // Edit the second translation: remove the existing file.
+    $this->drupalGet('fr/node/' . $default_language_node->id() . '/edit');
+    $this->submitForm([], 'Remove');
+
+    // Upload a different file.
+    $edit = [];
+    $edit['title[0][value]'] = 'David Bowie';
+    $name = 'files[' . $this->fieldName . '_0]';
+    $edit[$name] = \Drupal::service('file_system')->realpath($this->drupalGetTestFiles('text')[3]->uri);
+    $this->submitForm($edit, 'Save (this translation)');
+    $replaced_second_fid = $this->getLastFileId();
+
+    \Drupal::entityTypeManager()->getStorage('file')->resetCache();
+
+    // Ensure the first and third files are untouched.
+    $file = File::load($first_fid);
+    $this->assertTrue($file->isPermanent(), 'First file still exists and is permanent.');
+
+    $file = File::load($third_fid);
+    $this->assertTrue($file->isPermanent());
+
+    // Ensure the file status of the replaced second file is permanent.
+    $file = File::load($replaced_second_fid);
+    $this->assertTrue($file->isPermanent());
+
+    // Delete the third translation.
+    $this->drupalGet('nl/node/' . $default_language_node->id() . '/delete');
+    $this->submitForm([], 'Delete Dutch translation');
+
+    \Drupal::entityTypeManager()->getStorage('file')->resetCache();
+
+    // Ensure the first and replaced second files are untouched.
+    $file = File::load($first_fid);
+    $this->assertTrue($file->isPermanent(), 'First file still exists and is permanent.');
+
+    $file = File::load($replaced_second_fid);
+    $this->assertTrue($file->isPermanent());
+
+    // Ensure the file status of the third file is now temporary.
+    $file = File::load($third_fid);
+    $this->assertTrue($file->isTemporary());
+
+    // Delete the all translations.
+    $this->drupalGet('node/' . $default_language_node->id() . '/delete');
+    $this->submitForm([], 'Delete all translations');
+
+    \Drupal::entityTypeManager()->getStorage('file')->resetCache();
+
+    // Ensure the file status of the all files are now temporary.
+    $file = File::load($first_fid);
+    $this->assertTrue($file->isTemporary(), 'First file still exists and is temporary.');
+
+    $file = File::load($replaced_second_fid);
+    $this->assertTrue($file->isTemporary());
+  }
+
+  /**
+   * Tests if file field tracks file usages correctly on translated nodes.
+   */
+  public function testFileUsage(): void {
+    /** @var \Drupal\file\FileUsage\FileUsageInterface $file_usage */
+    $file_usage = \Drupal::service('file.usage');
+
+    // Enable language selector on the page edit form.
+    $edit = [
+      'language_configuration[language_alterable]' => 1,
+    ];
+    $this->drupalGet('admin/structure/types/manage/page');
+    $this->submitForm($edit, 'Save');
+
+    // Create a node and upload a file.
+    $node = $this->drupalCreateNode(['type' => 'page']);
+    $edit = [
+      'files[' . $this->fieldName . '_0]' => \Drupal::service('file_system')->realpath($this->drupalGetTestFiles('text')[0]->uri),
+    ];
+    $this->drupalGet('node/' . $node->id() . '/edit');
+    $this->submitForm($edit, 'Save');
+
+    // Check if the file usage is correct.
+    $file = File::load($this->getLastFileId());
+    $this->assertEquals($file_usage->listUsage($file), ['file' => ['node' => [$node->id() => '1']]]);
+
+    // Check if the file usage is tracked correctly when changing the original
+    // language of an entity.
+    $edit = [
+      'langcode[0][value]' => 'fr',
+    ];
+    $this->drupalGet('node/' . $node->id() . '/edit');
+    $this->submitForm($edit, 'Save');
+    $this->assertEquals($file_usage->listUsage($file), ['file' => ['node' => [$node->id() => '1']]]);
+  }
+
+}

core/modules/file/tests/src/Functional/FilePrivateTest.php

@@ -0,0 +1,250 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+use Drupal\file\Entity\File;
+use Drupal\node\Entity\NodeType;
+use Drupal\user\RoleInterface;
+
+/**
+ * Uploads a test to a private node and checks access.
+ *
+ * @group file
+ */
+class FilePrivateTest extends FileFieldTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  protected static $modules = ['node_access_test', 'field_test'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    node_access_test_add_field(NodeType::load('article'));
+    node_access_rebuild();
+    \Drupal::state()->set('node_access_test.private', TRUE);
+    // This test expects unused managed files to be marked as a temporary file.
+    $this->config('file.settings')
+      ->set('make_unused_managed_files_temporary', TRUE)
+      ->save();
+  }
+
+  /**
+   * Tests file access for file uploaded to a private node.
+   */
+  public function testPrivateFile(): void {
+    $node_storage = $this->container->get('entity_type.manager')->getStorage('node');
+    /** @var \Drupal\Core\File\FileSystemInterface $file_system */
+    $file_system = \Drupal::service('file_system');
+    $type_name = 'article';
+    $field_name = $this->randomMachineName();
+    $this->createFileField($field_name, 'node', $type_name, ['uri_scheme' => 'private']);
+
+    $test_file = $this->getTestFile('text');
+    $nid = $this->uploadNodeFile($test_file, $field_name, $type_name, TRUE, ['private' => TRUE]);
+    \Drupal::entityTypeManager()->getStorage('node')->resetCache([$nid]);
+    /** @var \Drupal\node\NodeInterface $node */
+    $node = $node_storage->load($nid);
+    $node_file = File::load($node->{$field_name}->target_id);
+    // Ensure the file can be viewed.
+    $this->drupalGet('node/' . $node->id());
+    $this->assertSession()->responseContains($node_file->getFilename());
+    // Ensure the file can be downloaded.
+    $this->drupalGet($node_file->createFileUrl(FALSE));
+    $this->assertSession()->statusCodeEquals(200);
+    $this->drupalLogOut();
+    // Ensure the file cannot be downloaded after logging out.
+    $this->drupalGet($node_file->createFileUrl(FALSE));
+    $this->assertSession()->statusCodeEquals(403);
+
+    // Create a field with no view access. See
+    // field_test_entity_field_access().
+    $no_access_field_name = 'field_no_view_access';
+    $this->createFileField($no_access_field_name, 'node', $type_name, ['uri_scheme' => 'private']);
+    // Test with the field that should deny access through field access.
+    $this->drupalLogin($this->adminUser);
+    $nid = $this->uploadNodeFile($test_file, $no_access_field_name, $type_name, TRUE, ['private' => TRUE]);
+    \Drupal::entityTypeManager()->getStorage('node')->resetCache([$nid]);
+    $node = $node_storage->load($nid);
+    $node_file = File::load($node->{$no_access_field_name}->target_id);
+
+    // Ensure the file cannot be downloaded.
+    $file_url = $node_file->createFileUrl(FALSE);
+    $this->drupalGet($file_url);
+    $this->assertSession()->statusCodeEquals(403);
+
+    // Attempt to reuse the file when editing a node.
+    $edit = [];
+    $edit['title[0][value]'] = $this->randomMachineName();
+    $this->drupalGet('node/add/' . $type_name);
+    $this->submitForm($edit, 'Save');
+    $new_node = $this->drupalGetNodeByTitle($edit['title[0][value]']);
+
+    // Can't use submitForm() to set hidden fields.
+    $this->drupalGet('node/' . $new_node->id() . '/edit');
+    $this->getSession()->getPage()->find('css', 'input[name="' . $field_name . '[0][fids]"]')->setValue($node_file->id());
+    $this->getSession()->getPage()->pressButton('Save');
+    $this->assertSession()->addressEquals('node/' . $new_node->id());
+    // Make sure the submitted hidden file field is empty.
+    $new_node = \Drupal::entityTypeManager()->getStorage('node')->loadUnchanged($new_node->id());
+    $this->assertTrue($new_node->get($field_name)->isEmpty());
+    // Attempt to reuse the existing file when creating a new node, and confirm
+    // that access is still denied.
+    $edit = [];
+    $edit['title[0][value]'] = $this->randomMachineName();
+    // Can't use submitForm() to set hidden fields.
+    $this->drupalGet('node/add/' . $type_name);
+    $this->getSession()->getPage()->find('css', 'input[name="title[0][value]"]')->setValue($edit['title[0][value]']);
+    $this->getSession()->getPage()->find('css', 'input[name="' . $field_name . '[0][fids]"]')->setValue($node_file->id());
+    $this->getSession()->getPage()->pressButton('Save');
+    $new_node = $this->drupalGetNodeByTitle($edit['title[0][value]']);
+    $this->assertSession()->addressEquals('node/' . $new_node->id());
+    // Make sure the submitted hidden file field is empty.
+    $new_node = \Drupal::entityTypeManager()->getStorage('node')->loadUnchanged($new_node->id());
+    $this->assertTrue($new_node->get($field_name)->isEmpty());
+
+    // Now make file_test_file_download() return everything.
+    \Drupal::state()->set('file_test.allow_all', TRUE);
+    // Delete the node.
+    $node->delete();
+    // Ensure the temporary file can still be downloaded by the owner.
+    $this->drupalGet($file_url);
+    $this->assertSession()->statusCodeEquals(200);
+
+    // Ensure the temporary file cannot be downloaded by an anonymous user.
+    $this->drupalLogout();
+    $this->drupalGet($file_url);
+    $this->assertSession()->statusCodeEquals(403);
+
+    // Ensure the temporary file cannot be downloaded by another user.
+    $account = $this->drupalCreateUser();
+    $this->drupalLogin($account);
+    $this->drupalGet($file_url);
+    $this->assertSession()->statusCodeEquals(403);
+
+    // As an anonymous user, create a temporary file with no references and
+    // confirm that only the session that uploaded it may view it.
+    $this->drupalLogout();
+    user_role_change_permissions(
+      RoleInterface::ANONYMOUS_ID,
+      [
+        "create $type_name content" => TRUE,
+        'access content' => TRUE,
+      ]
+    );
+    $test_file = $this->getTestFile('text');
+    $this->drupalGet('node/add/' . $type_name);
+    $edit = ['files[' . $field_name . '_0]' => $file_system->realpath($test_file->getFileUri())];
+    $this->submitForm($edit, 'Upload');
+    /** @var \Drupal\file\FileStorageInterface $file_storage */
+    $file_storage = $this->container->get('entity_type.manager')->getStorage('file');
+    $files = $file_storage->loadByProperties(['uid' => 0]);
+    $this->assertCount(1, $files, 'Loaded one anonymous file.');
+    $file = end($files);
+    $this->assertTrue($file->isTemporary(), 'File is temporary.');
+    $usage = $this->container->get('file.usage')->listUsage($file);
+    $this->assertEmpty($usage, 'No file usage found.');
+    $file_url = $file->createFileUrl(FALSE);
+    // Ensure the anonymous uploader has access to the temporary file.
+    $this->drupalGet($file_url);
+    $this->assertSession()->statusCodeEquals(200);
+    // Close the prior connection and remove the session cookie.
+    $this->getSession()->reset();
+    // Ensure that a different anonymous user cannot access the temporary file.
+    $this->drupalGet($file_url);
+    $this->assertSession()->statusCodeEquals(403);
+
+    // As an anonymous user, create a permanent file, then remove all
+    // references to the file (so that it becomes temporary again) and confirm
+    // that only the session that uploaded it may view it.
+    $test_file = $this->getTestFile('text');
+    $this->drupalGet('node/add/' . $type_name);
+    $edit = [];
+    $edit['title[0][value]'] = $this->randomMachineName();
+    $edit['files[' . $field_name . '_0]'] = $file_system->realpath($test_file->getFileUri());
+    $this->submitForm($edit, 'Save');
+    $new_node = $this->drupalGetNodeByTitle($edit['title[0][value]']);
+    $file_id = $new_node->{$field_name}->target_id;
+    $file = File::load($file_id);
+    $this->assertTrue($file->isPermanent(), 'File is permanent.');
+    // Remove the reference to this file.
+    $new_node->{$field_name} = [];
+    $new_node->save();
+    $file = File::load($file_id);
+    $this->assertTrue($file->isTemporary(), 'File is temporary.');
+    $usage = $this->container->get('file.usage')->listUsage($file);
+    $this->assertEmpty($usage, 'No file usage found.');
+    $file_url = $file->createFileUrl(FALSE);
+    // Ensure the anonymous uploader has access to the temporary file.
+    $this->drupalGet($file_url);
+    $this->assertSession()->statusCodeEquals(200);
+    // Close the prior connection and remove the session cookie.
+    $this->getSession()->reset();
+    // Ensure that a different anonymous user cannot access the temporary file.
+    $this->drupalGet($file_url);
+    $this->assertSession()->statusCodeEquals(403);
+
+    // As an anonymous user, create a permanent file that is referenced by a
+    // published node and confirm that all anonymous users may view it.
+    $test_file = $this->getTestFile('text');
+    $this->drupalGet('node/add/' . $type_name);
+    $edit = [];
+    $edit['title[0][value]'] = $this->randomMachineName();
+    $edit['files[' . $field_name . '_0]'] = $file_system->realpath($test_file->getFileUri());
+    $this->submitForm($edit, 'Save');
+    $new_node = $this->drupalGetNodeByTitle($edit['title[0][value]']);
+    $file = File::load($new_node->{$field_name}->target_id);
+    $this->assertTrue($file->isPermanent(), 'File is permanent.');
+    $usage = $this->container->get('file.usage')->listUsage($file);
+    $this->assertCount(1, $usage, 'File usage found.');
+    $file_url = $file->createFileUrl(FALSE);
+    // Ensure the anonymous uploader has access to the file.
+    $this->drupalGet($file_url);
+    $this->assertSession()->statusCodeEquals(200);
+    // Close the prior connection and remove the session cookie.
+    $this->getSession()->reset();
+    // Ensure that a different anonymous user can access the file.
+    $this->drupalGet($file_url);
+    $this->assertSession()->statusCodeEquals(200);
+
+    // As an anonymous user, create a permanent file that is referenced by an
+    // unpublished node and confirm that no anonymous users may view it (even
+    // the session that uploaded the file) because they cannot view the
+    // unpublished node.
+    $test_file = $this->getTestFile('text');
+    $this->drupalGet('node/add/' . $type_name);
+    $edit = [];
+    $edit['title[0][value]'] = $this->randomMachineName();
+    $edit['files[' . $field_name . '_0]'] = $file_system->realpath($test_file->getFileUri());
+    $this->submitForm($edit, 'Save');
+    $new_node = $this->drupalGetNodeByTitle($edit['title[0][value]']);
+    $new_node->setUnpublished();
+    $new_node->save();
+    $file = File::load($new_node->{$field_name}->target_id);
+    $this->assertTrue($file->isPermanent(), 'File is permanent.');
+    $usage = $this->container->get('file.usage')->listUsage($file);
+    $this->assertCount(1, $usage, 'File usage found.');
+    $file_url = $file->createFileUrl(FALSE);
+    // Ensure the anonymous uploader cannot access to the file.
+    $this->drupalGet($file_url);
+    $this->assertSession()->statusCodeEquals(403);
+    // Close the prior connection and remove the session cookie.
+    $this->getSession()->reset();
+    // Ensure that a different anonymous user cannot access the temporary file.
+    $this->drupalGet($file_url);
+    $this->assertSession()->statusCodeEquals(403);
+  }
+
+}

core/modules/file/tests/src/Functional/FileTokenReplaceTest.php

@@ -0,0 +1,108 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+use Drupal\Component\Utility\Html;
+use Drupal\Core\Render\BubbleableMetadata;
+use Drupal\Core\StringTranslation\ByteSizeMarkup;
+use Drupal\file\Entity\File;
+
+/**
+ * Tests file token replacement.
+ *
+ * @group file
+ */
+class FileTokenReplaceTest extends FileFieldTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * Creates a file, then tests the tokens generated from it.
+   */
+  public function testFileTokenReplacement(): void {
+    $node_storage = $this->container->get('entity_type.manager')->getStorage('node');
+    $token_service = \Drupal::token();
+    $language_interface = \Drupal::languageManager()->getCurrentLanguage();
+    /** @var \Drupal\Core\Datetime\DateFormatterInterface $date_formatter */
+    $date_formatter = $this->container->get('date.formatter');
+
+    // Create file field.
+    $type_name = 'article';
+    $field_name = 'field_' . $this->randomMachineName();
+    $this->createFileField($field_name, 'node', $type_name);
+
+    $test_file = $this->getTestFile('text');
+    // Coping a file to test uploads with non-latin filenames.
+    // cSpell:disable-next-line
+    $filename = \Drupal::service('file_system')->dirname($test_file->getFileUri()) . '/текстовый файл.txt';
+    $test_file = \Drupal::service('file.repository')->copy($test_file, $filename);
+
+    // Create a new node with the uploaded file.
+    $nid = $this->uploadNodeFile($test_file, $field_name, $type_name);
+
+    // Load the node and the file.
+    $node_storage->resetCache([$nid]);
+    $node = $node_storage->load($nid);
+    $file = File::load($node->{$field_name}->target_id);
+
+    // Generate and test sanitized tokens.
+    $tests = [];
+    $tests['[file:fid]'] = $file->id();
+    $tests['[file:name]'] = Html::escape($file->getFilename());
+    $tests['[file:path]'] = Html::escape($file->getFileUri());
+    $tests['[file:mime]'] = Html::escape($file->getMimeType());
+    $tests['[file:size]'] = ByteSizeMarkup::create($file->getSize());
+    $tests['[file:url]'] = Html::escape($file->createFileUrl(FALSE));
+    $tests['[file:created]'] = $date_formatter->format($file->getCreatedTime(), 'medium', '', NULL, $language_interface->getId());
+    $tests['[file:created:short]'] = $date_formatter->format($file->getCreatedTime(), 'short', '', NULL, $language_interface->getId());
+    $tests['[file:changed]'] = $date_formatter->format($file->getChangedTime(), 'medium', '', NULL, $language_interface->getId());
+    $tests['[file:changed:short]'] = $date_formatter->format($file->getChangedTime(), 'short', '', NULL, $language_interface->getId());
+    $tests['[file:owner]'] = Html::escape($this->adminUser->getDisplayName());
+    $tests['[file:owner:uid]'] = $file->getOwnerId();
+
+    $base_bubbleable_metadata = BubbleableMetadata::createFromObject($file);
+    $metadata_tests = [];
+    $metadata_tests['[file:fid]'] = $base_bubbleable_metadata;
+    $metadata_tests['[file:name]'] = $base_bubbleable_metadata;
+    $metadata_tests['[file:path]'] = $base_bubbleable_metadata;
+    $metadata_tests['[file:mime]'] = $base_bubbleable_metadata;
+    $metadata_tests['[file:size]'] = $base_bubbleable_metadata;
+    $bubbleable_metadata = clone $base_bubbleable_metadata;
+    $metadata_tests['[file:url]'] = $bubbleable_metadata->addCacheContexts(['url.site']);
+    $bubbleable_metadata = clone $base_bubbleable_metadata;
+    $metadata_tests['[file:created]'] = $bubbleable_metadata->addCacheTags(['rendered']);
+    $metadata_tests['[file:created:short]'] = $bubbleable_metadata;
+    $metadata_tests['[file:changed]'] = $bubbleable_metadata;
+    $metadata_tests['[file:changed:short]'] = $bubbleable_metadata;
+    $bubbleable_metadata = clone $base_bubbleable_metadata;
+    $metadata_tests['[file:owner]'] = $bubbleable_metadata->addCacheTags(['user:2']);
+    $metadata_tests['[file:owner:uid]'] = $bubbleable_metadata;
+
+    // Test to make sure that we generated something for each token.
+    $this->assertNotContains(0, array_map('strlen', $tests), 'No empty tokens generated.');
+
+    foreach ($tests as $input => $expected) {
+      $bubbleable_metadata = new BubbleableMetadata();
+      $output = $token_service->replace($input, ['file' => $file], ['langcode' => $language_interface->getId()], $bubbleable_metadata);
+      $this->assertEquals($expected, $output, "Sanitized file token $input replaced.");
+      $this->assertEquals($metadata_tests[$input], $bubbleable_metadata);
+    }
+
+    // Generate and test unsanitized tokens.
+    $tests['[file:name]'] = $file->getFilename();
+    $tests['[file:path]'] = $file->getFileUri();
+    $tests['[file:mime]'] = $file->getMimeType();
+    $tests['[file:size]'] = ByteSizeMarkup::create($file->getSize());
+
+    foreach ($tests as $input => $expected) {
+      $output = $token_service->replace($input, ['file' => $file], ['langcode' => $language_interface->getId(), 'sanitize' => FALSE]);
+      $this->assertEquals($expected, $output, "Unsanitized file token $input replaced.");
+    }
+  }
+
+}

core/modules/file/tests/src/Functional/FileUploadJsonBasicAuthTest.php

@@ -0,0 +1,43 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+use Drupal\Tests\rest\Functional\BasicAuthResourceTestTrait;
+use Drupal\Tests\rest\Functional\FileUploadResourceTestBase;
+
+/**
+ * @group file
+ * @group #slow
+ */
+class FileUploadJsonBasicAuthTest extends FileUploadResourceTestBase {
+
+  use BasicAuthResourceTestTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['basic_auth'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $format = 'json';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $mimeType = 'application/json';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $auth = 'basic_auth';
+
+}

core/modules/file/tests/src/Functional/FileUploadJsonCookieTest.php

@@ -0,0 +1,45 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+use Drupal\Tests\rest\Functional\CookieResourceTestTrait;
+use Drupal\Tests\rest\Functional\FileUploadResourceTestBase;
+
+/**
+ * @group file
+ * @group #slow
+ */
+class FileUploadJsonCookieTest extends FileUploadResourceTestBase {
+
+  use CookieResourceTestTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $format = 'json';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $mimeType = 'application/json';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $auth = 'cookie';
+
+  /**
+   * Entity type ID for this storage.
+   *
+   * @var string
+   */
+  protected static string $entityTypeId;
+
+}

core/modules/file/tests/src/Functional/Formatter/FileAudioFormatterTest.php

@@ -0,0 +1,65 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional\Formatter;
+
+use Drupal\entity_test\Entity\EntityTest;
+use Drupal\file\Entity\File;
+
+/**
+ * @coversDefaultClass \Drupal\file\Plugin\Field\FieldFormatter\FileAudioFormatter
+ * @group file
+ */
+class FileAudioFormatterTest extends FileMediaFormatterTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * @covers ::viewElements
+   *
+   * @dataProvider dataProvider
+   */
+  public function testRender($tag_count, $formatter_settings): void {
+    $field_config = $this->createMediaField('file_audio', 'mp3', $formatter_settings);
+
+    file_put_contents('public://file.mp3', str_repeat('t', 10));
+    $file1 = File::create([
+      'uri' => 'public://file.mp3',
+      'filename' => 'file.mp3',
+    ]);
+    $file1->save();
+
+    $file2 = File::create([
+      'uri' => 'public://file.mp3',
+      'filename' => 'file.mp3',
+    ]);
+    $file2->save();
+
+    $entity = EntityTest::create([
+      $field_config->getName() => [
+        [
+          'target_id' => $file1->id(),
+        ],
+        [
+          'target_id' => $file2->id(),
+        ],
+      ],
+    ]);
+    $entity->save();
+
+    $this->drupalGet($entity->toUrl());
+
+    $file1_url = $file1->createFileUrl();
+    $file2_url = $file2->createFileUrl();
+
+    $assert_session = $this->assertSession();
+    $assert_session->elementsCount('css', 'audio[controls="controls"]', $tag_count);
+    $assert_session->elementExists('css', "audio > source[src='$file1_url'][type='audio/mpeg']");
+    $assert_session->elementExists('css', "audio > source[src='$file2_url'][type='audio/mpeg']");
+  }
+
+}

core/modules/file/tests/src/Functional/Formatter/FileMediaFormatterTestBase.php

@@ -0,0 +1,96 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional\Formatter;
+
+use Drupal\Core\Field\FieldStorageDefinitionInterface;
+use Drupal\field\Entity\FieldConfig;
+use Drupal\field\Entity\FieldStorageConfig;
+use Drupal\Tests\BrowserTestBase;
+
+/**
+ * Provides methods specifically for testing File module's media formatter's.
+ */
+abstract class FileMediaFormatterTestBase extends BrowserTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = [
+    'entity_test',
+    'field',
+    'file',
+    'user',
+    'system',
+  ];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    $this->drupalLogin($this->drupalCreateUser(['view test entity']));
+  }
+
+  /**
+   * Creates a file field and set's the correct formatter.
+   *
+   * @param string $formatter
+   *   The formatter ID.
+   * @param string $file_extensions
+   *   The file extensions of the new field.
+   * @param array $formatter_settings
+   *   Settings for the formatter.
+   *
+   * @return \Drupal\field\Entity\FieldConfig
+   *   Newly created file field.
+   */
+  protected function createMediaField($formatter, $file_extensions, array $formatter_settings = []) {
+    $entity_type = $bundle = 'entity_test';
+    $field_name = $this->randomMachineName();
+
+    FieldStorageConfig::create([
+      'entity_type' => $entity_type,
+      'field_name' => $field_name,
+      'type' => 'file',
+      'cardinality' => FieldStorageDefinitionInterface::CARDINALITY_UNLIMITED,
+    ])->save();
+    $field_config = FieldConfig::create([
+      'entity_type' => $entity_type,
+      'field_name' => $field_name,
+      'bundle' => $bundle,
+      'settings' => [
+        'file_extensions' => trim($file_extensions),
+      ],
+    ]);
+    $field_config->save();
+
+    $this->container->get('entity_display.repository')
+      ->getViewDisplay('entity_test', 'entity_test', 'full')
+      ->setComponent($field_name, [
+        'type' => $formatter,
+        'settings' => $formatter_settings,
+      ])
+      ->save();
+
+    return $field_config;
+  }
+
+  /**
+   * Data provider for testRender.
+   *
+   * @return array
+   *   An array of data arrays.
+   *   The data array contains:
+   *     - The number of expected HTML tags.
+   *     - An array of settings for the field formatter.
+   */
+  public static function dataProvider(): array {
+    return [
+      [2, []],
+      [1, ['multiple_file_display_type' => 'sources']],
+    ];
+  }
+
+}

core/modules/file/tests/src/Functional/Formatter/FileVideoFormatterTest.php

@@ -0,0 +1,143 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional\Formatter;
+
+use Drupal\entity_test\Entity\EntityTest;
+use Drupal\file\Entity\File;
+
+/**
+ * @coversDefaultClass \Drupal\file\Plugin\Field\FieldFormatter\FileVideoFormatter
+ * @group file
+ */
+class FileVideoFormatterTest extends FileMediaFormatterTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * @covers ::viewElements
+   *
+   * @dataProvider dataProvider
+   */
+  public function testRender($tag_count, $formatter_settings): void {
+    $field_config = $this->createMediaField('file_video', 'mp4', $formatter_settings);
+
+    file_put_contents('public://file.mp4', str_repeat('t', 10));
+    $file1 = File::create([
+      'uri' => 'public://file.mp4',
+      'filename' => 'file.mp4',
+    ]);
+    $file1->save();
+
+    $file2 = File::create([
+      'uri' => 'public://file.mp4',
+      'filename' => 'file.mp4',
+    ]);
+    $file2->save();
+
+    $entity = EntityTest::create([
+      $field_config->getName() => [
+        [
+          'target_id' => $file1->id(),
+        ],
+        [
+          'target_id' => $file2->id(),
+        ],
+      ],
+    ]);
+    $entity->save();
+
+    $this->drupalGet($entity->toUrl());
+
+    $file1_url = $file1->createFileUrl();
+    $file2_url = $file2->createFileUrl();
+
+    $assert_session = $this->assertSession();
+    $assert_session->elementsCount('css', 'video[controls="controls"]', $tag_count);
+    $assert_session->elementExists('css', "video > source[src='$file1_url'][type='video/mp4']");
+    $assert_session->elementExists('css', "video > source[src='$file2_url'][type='video/mp4']");
+  }
+
+  /**
+   * Tests that the attributes added to the formatter are applied on render.
+   */
+  public function testAttributes(): void {
+    $field_config = $this->createMediaField(
+      'file_video',
+      'mp4',
+      [
+        'autoplay' => TRUE,
+        'loop' => TRUE,
+        'muted' => TRUE,
+        'width' => 800,
+        'height' => 600,
+      ]
+    );
+
+    file_put_contents('public://file.mp4', str_repeat('t', 10));
+    $file = File::create([
+      'uri' => 'public://file.mp4',
+      'filename' => 'file.mp4',
+    ]);
+    $file->save();
+
+    $entity = EntityTest::create([
+      $field_config->getName() => [
+        [
+          'target_id' => $file->id(),
+        ],
+      ],
+    ]);
+    $entity->save();
+
+    $this->drupalGet($entity->toUrl());
+
+    $file_url = \Drupal::service('file_url_generator')->generateString($file->getFileUri());
+
+    $assert_session = $this->assertSession();
+    $assert_session->elementExists('css', "video[autoplay='autoplay'] > source[src='$file_url'][type='video/mp4']");
+    $assert_session->elementExists('css', "video[loop='loop'] > source[src='$file_url'][type='video/mp4']");
+    $assert_session->elementExists('css', "video[muted='muted'] > source[src='$file_url'][type='video/mp4']");
+    $assert_session->elementExists('css', "video[width='800'] > source[src='$file_url'][type='video/mp4']");
+    $assert_session->elementExists('css', "video[height='600'] > source[src='$file_url'][type='video/mp4']");
+
+    /** @var \Drupal\Core\Entity\EntityDisplayRepositoryInterface $displayRepository */
+    $displayRepository = $this->container->get('entity_display.repository');
+    $entityDisplay = $displayRepository->getViewDisplay('entity_test', 'entity_test', 'full');
+    $fieldName = $field_config->get('field_name');
+    $fieldDisplay = $entityDisplay->getComponent($fieldName);
+
+    // Tests only setting width.
+    $fieldDisplay['settings']['height'] = NULL;
+    $entityDisplay->setComponent($fieldName, $fieldDisplay);
+    $entityDisplay->save();
+
+    $this->drupalGet($entity->toUrl());
+    $assert_session->elementAttributeNotExists('css', 'video', 'height');
+
+    // Tests only setting height.
+    $fieldDisplay['settings']['height'] = 600;
+    $fieldDisplay['settings']['width'] = NULL;
+    $entityDisplay->setComponent($fieldName, $fieldDisplay);
+    $entityDisplay->save();
+
+    $this->drupalGet($entity->toUrl());
+    $assert_session->elementAttributeNotExists('css', 'video', 'width');
+
+    // Tests both height and width empty.
+    $fieldDisplay['settings']['height'] = NULL;
+    $fieldDisplay['settings']['width'] = NULL;
+    $entityDisplay->setComponent($fieldName, $fieldDisplay);
+    $entityDisplay->save();
+
+    $this->drupalGet($entity->toUrl());
+    $assert_session->elementAttributeNotExists('css', 'video', 'height');
+    $assert_session->elementAttributeNotExists('css', 'video', 'width');
+
+  }
+
+}

core/modules/file/tests/src/Functional/GenericTest.php

@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+use Drupal\Tests\system\Functional\Module\GenericModuleTestBase;
+
+/**
+ * Generic module test for file.
+ *
+ * @group file
+ */
+class GenericTest extends GenericModuleTestBase {}

core/modules/file/tests/src/Functional/MultipleFileUploadTest.php

@@ -0,0 +1,66 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+use Drupal\Tests\BrowserTestBase;
+
+/**
+ * Tests multiple file upload.
+ *
+ * @group file
+ */
+class MultipleFileUploadTest extends BrowserTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['file'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+
+    $admin = $this->drupalCreateUser(['administer themes']);
+    $this->drupalLogin($admin);
+  }
+
+  /**
+   * Tests multiple file field with all file extensions.
+   */
+  public function testMultipleFileFieldWithAllFileExtensions(): void {
+    $theme = 'test_theme_settings';
+    \Drupal::service('theme_installer')->install([$theme]);
+    $this->drupalGet("admin/appearance/settings/$theme");
+
+    $edit = [];
+    // Create few files with non-typical extensions.
+    foreach (['file1.wtf', 'file2.wtf'] as $i => $file) {
+      $file_path = $this->root . "/sites/default/files/simpletest/$file";
+      file_put_contents($file_path, 'File with non-default extension.', FILE_APPEND | LOCK_EX);
+      $edit["files[multi_file][$i]"] = $file_path;
+    }
+
+    // @todo Replace after https://www.drupal.org/project/drupal/issues/2917885
+    $this->drupalGet("admin/appearance/settings/$theme");
+    $submit_xpath = $this->assertSession()->buttonExists('Save configuration')->getXpath();
+    $client = $this->getSession()->getDriver()->getClient();
+    $form = $client->getCrawler()->filterXPath($submit_xpath)->form();
+    $client->request($form->getMethod(), $form->getUri(), $form->getPhpValues(), $edit);
+
+    $page = $this->getSession()->getPage();
+    $this->assertStringNotContainsString('Only files with the following extensions are allowed', $page->getContent());
+    $this->assertStringContainsString('The configuration options have been saved.', $page->getContent());
+    $this->assertStringContainsString('file1.wtf', $page->getContent());
+    $this->assertStringContainsString('file2.wtf', $page->getContent());
+  }
+
+}

core/modules/file/tests/src/Functional/PrivateFileOnTranslatedEntityTest.php

@@ -0,0 +1,147 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+use Drupal\file\Entity\File;
+use Drupal\node\Entity\Node;
+use Drupal\Tests\content_translation\Traits\ContentTranslationTestTrait;
+
+/**
+ * Uploads private files to translated node and checks access.
+ *
+ * @group file
+ */
+class PrivateFileOnTranslatedEntityTest extends FileFieldTestBase {
+
+  use ContentTranslationTestTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['language', 'content_translation'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * The name of the file field used in the test.
+   *
+   * @var string
+   */
+  protected $fieldName;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+
+    // Create the "Basic page" node type.
+    $this->drupalCreateContentType(['type' => 'page', 'name' => 'Basic page']);
+
+    // Create a file field on the "Basic page" node type.
+    $this->fieldName = $this->randomMachineName();
+    $this->createFileField($this->fieldName, 'node', 'page', ['uri_scheme' => 'private']);
+
+    // Create and log in user.
+    $permissions = [
+      'access administration pages',
+      'administer content translation',
+      'administer content types',
+      'administer languages',
+      'create content translations',
+      'create page content',
+      'edit any page content',
+      'translate any entity',
+    ];
+    $admin_user = $this->drupalCreateUser($permissions);
+    $this->drupalLogin($admin_user);
+
+    // Add a second language.
+    static::createLanguageFromLangcode('fr');
+
+    // Enable translation for "Basic page" nodes.
+    static::enableContentTranslation('node', 'page');
+    static::setFieldTranslatable('node', 'page', $this->fieldName, TRUE);
+  }
+
+  /**
+   * Tests private file fields on translated nodes.
+   */
+  public function testPrivateLanguageFile(): void {
+    // Verify that the file field on the "Basic page" node type is translatable.
+    $definitions = \Drupal::service('entity_field.manager')->getFieldDefinitions('node', 'page');
+    $this->assertTrue($definitions[$this->fieldName]->isTranslatable(), 'Node file field is translatable.');
+
+    // Create a default language node.
+    $default_language_node = $this->drupalCreateNode(['type' => 'page']);
+
+    // Edit the node to upload a file.
+    $file = File::create(
+      [
+        'uri' => $this->drupalGetTestFiles('text')[0]->uri,
+      ]
+    );
+    $file->save();
+
+    $default_language_node->set($this->fieldName, $file->id());
+    $default_language_node->save();
+    $last_fid_prior = $this->getLastFileId();
+
+    // Languages are cached on many levels, and we need to clear those caches.
+    $this->rebuildContainer();
+
+    // Ensure the file can be downloaded.
+    \Drupal::entityTypeManager()->getStorage('node')->resetCache([$default_language_node->id()]);
+    $node = Node::load($default_language_node->id());
+    $node_file = File::load($node->{$this->fieldName}->target_id);
+    $this->drupalGet($node_file->createFileUrl(FALSE));
+    $this->assertSession()->statusCodeEquals(200);
+
+    // Translate the node into French.
+    $node->addTranslation(
+      'fr', [
+        'title' => $this->randomString(),
+      ]
+    );
+    $node->save();
+
+    // Remove the existing file.
+    $existing_file = $node->{$this->fieldName}->entity;
+    if ($existing_file) {
+      $node->set($this->fieldName, NULL);
+      $existing_file->delete();
+      $node->save();
+    }
+
+    // Upload a different file.
+    $default_language_node = $node->getTranslation('fr');
+    $file = File::create(
+      [
+        'uri' => $this->drupalGetTestFiles('text')[1]->uri,
+      ]
+    );
+    $file->save();
+    $default_language_node->set($this->fieldName, $file->id());
+    $default_language_node->save();
+    $last_fid = $this->getLastFileId();
+
+    // Verify the translation was created.
+    \Drupal::entityTypeManager()->getStorage('node')->resetCache([$default_language_node->id()]);
+    $default_language_node = Node::load($default_language_node->id());
+    $this->assertTrue($default_language_node->hasTranslation('fr'), 'Node found in database.');
+    // Verify that the new file got saved.
+    $this->assertGreaterThan($last_fid_prior, $last_fid);
+
+    // Ensure the file attached to the translated node can be downloaded.
+    $french_node = $default_language_node->getTranslation('fr');
+    $node_file = File::load($french_node->{$this->fieldName}->target_id);
+    $this->drupalGet($node_file->createFileUrl(FALSE));
+    $this->assertSession()->statusCodeEquals(200);
+  }
+
+}

core/modules/file/tests/src/Functional/RemoteFileSaveUploadTest.php

@@ -0,0 +1,35 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+/**
+ * Tests the file uploading functions.
+ *
+ * @group file
+ * @group #slow
+ */
+class RemoteFileSaveUploadTest extends SaveUploadTest {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  protected static $modules = ['file_test'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    $this->config('system.file')->set('default_scheme', 'dummy-remote')->save();
+  }
+
+}

core/modules/file/tests/src/Functional/Rest/FileJsonAnonTest.php

@@ -0,0 +1,31 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional\Rest;
+
+use Drupal\Tests\rest\Functional\AnonResourceTestTrait;
+
+/**
+ * @group rest
+ */
+class FileJsonAnonTest extends FileResourceTestBase {
+
+  use AnonResourceTestTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $format = 'json';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $mimeType = 'application/json';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+}

core/modules/file/tests/src/Functional/Rest/FileJsonBasicAuthTest.php

@@ -0,0 +1,41 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional\Rest;
+
+use Drupal\Tests\rest\Functional\BasicAuthResourceTestTrait;
+
+/**
+ * @group rest
+ */
+class FileJsonBasicAuthTest extends FileResourceTestBase {
+
+  use BasicAuthResourceTestTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['basic_auth'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $format = 'json';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $mimeType = 'application/json';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $auth = 'basic_auth';
+
+}

core/modules/file/tests/src/Functional/Rest/FileJsonCookieTest.php

@@ -0,0 +1,36 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional\Rest;
+
+use Drupal\Tests\rest\Functional\CookieResourceTestTrait;
+
+/**
+ * @group rest
+ */
+class FileJsonCookieTest extends FileResourceTestBase {
+
+  use CookieResourceTestTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $format = 'json';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $mimeType = 'application/json';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $auth = 'cookie';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+}

core/modules/file/tests/src/Functional/Rest/FileResourceTestBase.php

@@ -0,0 +1,225 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional\Rest;
+
+use Drupal\file\Entity\File;
+use Drupal\Tests\rest\Functional\EntityResource\EntityResourceTestBase;
+use Drupal\user\Entity\User;
+
+abstract class FileResourceTestBase extends EntityResourceTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['file', 'user'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $entityTypeId = 'file';
+
+  /**
+   * @var \Drupal\file\FileInterface
+   */
+  protected $entity;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $patchProtectedFieldNames = [
+    'uri' => NULL,
+    'filemime' => NULL,
+    'filesize' => NULL,
+    'status' => NULL,
+    'changed' => NULL,
+  ];
+
+  /**
+   * @var \Drupal\user\UserInterface
+   */
+  protected $author;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUpAuthorization($method) {
+    switch ($method) {
+      case 'GET':
+        $this->grantPermissionsToTestedRole(['access content']);
+        break;
+
+      case 'PATCH':
+        // \Drupal\file\FileAccessControlHandler::checkAccess() grants 'update'
+        // access only to the user that owns the file. So there is no permission
+        // to grant: instead, the file owner must be changed from its default
+        // (user 1) to the current user.
+        $this->makeCurrentUserFileOwner();
+        return;
+
+      case 'DELETE':
+        $this->grantPermissionsToTestedRole(['delete any file']);
+        break;
+    }
+  }
+
+  /**
+   * Makes the current user the file owner.
+   */
+  protected function makeCurrentUserFileOwner() {
+    $account = static::$auth ? User::load(2) : User::load(0);
+    $this->entity->setOwnerId($account->id());
+    $this->entity->setOwner($account);
+    $this->entity->save();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function createEntity() {
+    $this->author = User::load(1);
+
+    $file = File::create();
+    $file->setOwnerId($this->author->id());
+    $file->setFilename('drupal.txt');
+    $file->setMimeType('text/plain');
+    $file->setFileUri('public://drupal.txt');
+    $file->setPermanent();
+    $file->save();
+
+    file_put_contents($file->getFileUri(), 'Drupal');
+
+    return $file;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getExpectedNormalizedEntity() {
+    return [
+      'changed' => [
+        [
+          'value' => (new \DateTime())->setTimestamp($this->entity->getChangedTime())->setTimezone(new \DateTimeZone('UTC'))->format(\DateTime::RFC3339),
+          'format' => \DateTime::RFC3339,
+        ],
+      ],
+      'created' => [
+        [
+          'value' => (new \DateTime())->setTimestamp((int) $this->entity->getCreatedTime())->setTimezone(new \DateTimeZone('UTC'))->format(\DateTime::RFC3339),
+          'format' => \DateTime::RFC3339,
+        ],
+      ],
+      'fid' => [
+        [
+          'value' => 1,
+        ],
+      ],
+      'filemime' => [
+        [
+          'value' => 'text/plain',
+        ],
+      ],
+      'filename' => [
+        [
+          'value' => 'drupal.txt',
+        ],
+      ],
+      'filesize' => [
+        [
+          'value' => (int) $this->entity->getSize(),
+        ],
+      ],
+      'langcode' => [
+        [
+          'value' => 'en',
+        ],
+      ],
+      'status' => [
+        [
+          'value' => TRUE,
+        ],
+      ],
+      'uid' => [
+        [
+          'target_id' => (int) $this->author->id(),
+          'target_type' => 'user',
+          'target_uuid' => $this->author->uuid(),
+          'url' => base_path() . 'user/' . $this->author->id(),
+        ],
+      ],
+      'uri' => [
+        [
+          'url' => base_path() . $this->siteDirectory . '/files/drupal.txt',
+          'value' => 'public://drupal.txt',
+        ],
+      ],
+      'uuid' => [
+        [
+          'value' => $this->entity->uuid(),
+        ],
+      ],
+    ];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getNormalizedPostEntity() {
+    return [
+      'uid' => [
+        [
+          'target_id' => $this->author->id(),
+        ],
+      ],
+      'filename' => [
+        [
+          'value' => 'drupal.txt',
+        ],
+      ],
+    ];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getNormalizedPatchEntity() {
+    return array_diff_key($this->getNormalizedPostEntity(), ['uid' => TRUE]);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getExpectedCacheContexts() {
+    return [
+      'url.site',
+      'user.permissions',
+    ];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function testPost(): void {
+    // Drupal does not allow creating file entities independently. It allows you
+    // to create file entities that are referenced from another entity (e.g. an
+    // image for a node's image field).
+    // For that purpose, there is the "file_upload" REST resource plugin.
+    // @see \Drupal\file\FileAccessControlHandler::checkCreateAccess()
+    // @see \Drupal\file\Plugin\rest\resource\FileUploadResource
+    $this->markTestSkipped();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getExpectedUnauthorizedAccessMessage($method) {
+    return match($method) {
+      'GET' => "The 'access content' permission is required.",
+      'PATCH' => "Only the file owner can update the file entity.",
+      'DELETE' => "The 'delete any file' permission is required.",
+      default =>  parent::getExpectedUnauthorizedAccessMessage($method),
+    };
+  }
+
+}

core/modules/file/tests/src/Functional/Rest/FileXmlAnonTest.php

@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional\Rest;
+
+use Drupal\Tests\rest\Functional\AnonResourceTestTrait;
+use Drupal\Tests\rest\Functional\EntityResource\XmlEntityNormalizationQuirksTrait;
+
+/**
+ * @group rest
+ */
+class FileXmlAnonTest extends FileResourceTestBase {
+
+  use AnonResourceTestTrait;
+  use XmlEntityNormalizationQuirksTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $format = 'xml';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $mimeType = 'text/xml; charset=UTF-8';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+}

core/modules/file/tests/src/Functional/Rest/FileXmlBasicAuthTest.php

@@ -0,0 +1,43 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional\Rest;
+
+use Drupal\Tests\rest\Functional\BasicAuthResourceTestTrait;
+use Drupal\Tests\rest\Functional\EntityResource\XmlEntityNormalizationQuirksTrait;
+
+/**
+ * @group rest
+ */
+class FileXmlBasicAuthTest extends FileResourceTestBase {
+
+  use BasicAuthResourceTestTrait;
+  use XmlEntityNormalizationQuirksTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['basic_auth'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $format = 'xml';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $mimeType = 'text/xml; charset=UTF-8';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $auth = 'basic_auth';
+
+}

core/modules/file/tests/src/Functional/Rest/FileXmlCookieTest.php

@@ -0,0 +1,38 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional\Rest;
+
+use Drupal\Tests\rest\Functional\CookieResourceTestTrait;
+use Drupal\Tests\rest\Functional\EntityResource\XmlEntityNormalizationQuirksTrait;
+
+/**
+ * @group rest
+ */
+class FileXmlCookieTest extends FileResourceTestBase {
+
+  use CookieResourceTestTrait;
+  use XmlEntityNormalizationQuirksTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $format = 'xml';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $mimeType = 'text/xml; charset=UTF-8';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $auth = 'cookie';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+}

core/modules/file/tests/src/Functional/SaveUploadFormTest.php

@@ -0,0 +1,598 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+use Drupal\Core\File\FileExists;
+use Drupal\file\Entity\File;
+use Drupal\Tests\TestFileCreationTrait;
+
+/**
+ * Tests the _file_save_upload_from_form() function.
+ *
+ * @group file
+ * @group #slow
+ *
+ * @see _file_save_upload_from_form()
+ */
+class SaveUploadFormTest extends FileManagedTestBase {
+
+  use TestFileCreationTrait {
+    getTestFiles as drupalGetTestFiles;
+  }
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  protected static $modules = ['dblog', 'file_validator_test'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * An image file path for uploading.
+   *
+   * @var \Drupal\file\FileInterface
+   */
+  protected $image;
+
+  /**
+   * A PHP file path for upload security testing.
+   *
+   * @var string
+   */
+  protected $phpFile;
+
+  /**
+   * The largest file id when the test starts.
+   *
+   * @var int
+   */
+  protected $maxFidBefore;
+
+  /**
+   * Extension of the image filename.
+   *
+   * @var string
+   */
+  protected $imageExtension;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    $account = $this->drupalCreateUser(['access site reports']);
+    $this->drupalLogin($account);
+
+    $image_files = $this->drupalGetTestFiles('image');
+    $this->image = File::create((array) current($image_files));
+
+    [, $this->imageExtension] = explode('.', $this->image->getFilename());
+    $this->assertFileExists($this->image->getFileUri());
+
+    $this->phpFile = current($this->drupalGetTestFiles('php'));
+    $this->assertFileExists($this->phpFile->uri);
+
+    $this->maxFidBefore = (int) \Drupal::entityQueryAggregate('file')
+      ->accessCheck(FALSE)
+      ->aggregate('fid', 'max')
+      ->execute()[0]['fid_max'];
+
+    /** @var \Drupal\Core\File\FileSystemInterface $file_system */
+    $file_system = \Drupal::service('file_system');
+    // Upload with replace to guarantee there's something there.
+    $edit = [
+      'file_test_replace' => FileExists::Replace->name,
+      'files[file_test_upload][]' => $file_system->realpath($this->image->getFileUri()),
+    ];
+    $this->drupalGet('file-test/save_upload_from_form_test');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains("You WIN!");
+
+    // Check that the correct hooks were called then clean out the hook
+    // counters.
+    $this->assertFileHooksCalled(['validate', 'insert']);
+    file_test_reset();
+  }
+
+  /**
+   * Tests the _file_save_upload_from_form() function.
+   */
+  public function testNormal(): void {
+    $max_fid_after = (int) \Drupal::entityQueryAggregate('file')
+      ->accessCheck(FALSE)
+      ->aggregate('fid', 'max')
+      ->execute()[0]['fid_max'];
+    // Verify that a new file was created.
+    $this->assertGreaterThan($this->maxFidBefore, $max_fid_after);
+    $file1 = File::load($max_fid_after);
+    $this->assertInstanceOf(File::class, $file1);
+    // MIME type of the uploaded image may be either image/jpeg or image/png.
+    $this->assertEquals('image', substr($file1->getMimeType(), 0, 5), 'A MIME type was set.');
+
+    // Reset the hook counters to get rid of the 'load' we just called.
+    file_test_reset();
+
+    // Upload a second file.
+    $image2 = current($this->drupalGetTestFiles('image'));
+    /** @var \Drupal\Core\File\FileSystemInterface $file_system */
+    $file_system = \Drupal::service('file_system');
+    $edit = ['files[file_test_upload][]' => $file_system->realpath($image2->uri)];
+    $this->drupalGet('file-test/save_upload_from_form_test');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains("You WIN!");
+    $max_fid_after = (int) \Drupal::entityQueryAggregate('file')
+      ->accessCheck(FALSE)
+      ->aggregate('fid', 'max')
+      ->execute()[0]['fid_max'];
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'insert']);
+
+    $file2 = File::load($max_fid_after);
+    $this->assertInstanceOf(File::class, $file2);
+    // MIME type of the uploaded image may be either image/jpeg or image/png.
+    $this->assertEquals('image', substr($file2->getMimeType(), 0, 5), 'A MIME type was set.');
+
+    // Load both files using File::loadMultiple().
+    $files = File::loadMultiple([$file1->id(), $file2->id()]);
+    $this->assertTrue(isset($files[$file1->id()]), 'File was loaded successfully');
+    $this->assertTrue(isset($files[$file2->id()]), 'File was loaded successfully');
+
+    // Upload a third file to a subdirectory.
+    $image3 = current($this->drupalGetTestFiles('image'));
+    $image3_realpath = $file_system->realpath($image3->uri);
+    $dir = $this->randomMachineName();
+    $edit = [
+      'files[file_test_upload][]' => $image3_realpath,
+      'file_subdir' => $dir,
+    ];
+    $this->drupalGet('file-test/save_upload_from_form_test');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains("You WIN!");
+    $this->assertFileExists('temporary://' . $dir . '/' . trim(\Drupal::service('file_system')->basename($image3_realpath)));
+  }
+
+  /**
+   * Tests extension handling.
+   */
+  public function testHandleExtension(): void {
+    /** @var \Drupal\Core\File\FileSystemInterface $file_system */
+    $file_system = \Drupal::service('file_system');
+    // The file being tested is a .gif which is in the default safe list
+    // of extensions to allow when the extension validator isn't used. This is
+    // implicitly tested at the testNormal() test. Here we tell
+    // _file_save_upload_from_form() to only allow ".foo".
+    $extensions = 'foo';
+    $edit = [
+      'file_test_replace' => FileExists::Replace->name,
+      'files[file_test_upload][]' => $file_system->realpath($this->image->getFileUri()),
+      'extensions' => $extensions,
+    ];
+
+    $this->drupalGet('file-test/save_upload_from_form_test');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->responseContains('Only files with the following extensions are allowed: <em class="placeholder">' . $extensions . '</em>');
+    $this->assertSession()->pageTextContains("Epic upload FAIL!");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate']);
+
+    // Reset the hook counters.
+    file_test_reset();
+
+    $extensions = 'foo ' . $this->imageExtension;
+    // Now tell _file_save_upload_from_form() to allow the extension of our test image.
+    $edit = [
+      'file_test_replace' => FileExists::Replace->name,
+      'files[file_test_upload][]' => $file_system->realpath($this->image->getFileUri()),
+      'extensions' => $extensions,
+    ];
+
+    $this->drupalGet('file-test/save_upload_from_form_test');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextNotContains('Only files with the following extensions are allowed:');
+    $this->assertSession()->pageTextContains("You WIN!");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'load', 'update']);
+
+    // Reset the hook counters.
+    file_test_reset();
+
+    // Now tell _file_save_upload_from_form() to allow any extension.
+    $edit = [
+      'file_test_replace' => FileExists::Replace->name,
+      'files[file_test_upload][]' => $file_system->realpath($this->image->getFileUri()),
+      'allow_all_extensions' => 'empty_array',
+    ];
+    $this->drupalGet('file-test/save_upload_from_form_test');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextNotContains('Only files with the following extensions are allowed:');
+    $this->assertSession()->pageTextContains("You WIN!");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'load', 'update']);
+  }
+
+  /**
+   * Tests dangerous file handling.
+   */
+  public function testHandleDangerousFile(): void {
+    $config = $this->config('system.file');
+    /** @var \Drupal\Core\File\FileSystemInterface $file_system */
+    $file_system = \Drupal::service('file_system');
+    // Allow the .php extension and make sure it gets renamed to .txt for
+    // safety. Also check to make sure its MIME type was changed.
+    $edit = [
+      'file_test_replace' => FileExists::Replace->name,
+      'files[file_test_upload][]' => $file_system->realpath($this->phpFile->uri),
+      'is_image_file' => FALSE,
+      'extensions' => 'php txt',
+    ];
+
+    $this->drupalGet('file-test/save_upload_from_form_test');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->responseContains('For security reasons, your upload has been renamed to <em class="placeholder">' . $this->phpFile->filename . '_.txt' . '</em>');
+    $this->assertSession()->pageTextContains('File MIME type is text/plain.');
+    $this->assertSession()->pageTextContains("You WIN!");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'insert']);
+
+    // Ensure dangerous files are not renamed when insecure uploads is TRUE.
+    // Turn on insecure uploads.
+    $config->set('allow_insecure_uploads', 1)->save();
+    // Reset the hook counters.
+    file_test_reset();
+
+    $this->drupalGet('file-test/save_upload_from_form_test');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextNotContains('For security reasons, your upload has been renamed');
+    $this->assertSession()->pageTextContains("File name is {$this->phpFile->filename}");
+    $this->assertSession()->pageTextContains("You WIN!");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'insert']);
+
+    // Turn off insecure uploads.
+    $config->set('allow_insecure_uploads', 0)->save();
+
+    // Reset the hook counters.
+    file_test_reset();
+
+    $edit = [
+      'file_test_replace' => FileExists::Replace->name,
+      'files[file_test_upload]' => \Drupal::service('file_system')->realpath($this->phpFile->uri),
+      'is_image_file' => FALSE,
+      'extensions' => 'php',
+    ];
+
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains('For security reasons, your upload has been rejected.');
+    $this->assertSession()->pageTextContains('Epic upload FAIL!');
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate']);
+  }
+
+  /**
+   * Tests file munge handling.
+   */
+  public function testHandleFileMunge(): void {
+    /** @var \Drupal\Core\File\FileSystemInterface $file_system */
+    $file_system = \Drupal::service('file_system');
+    // Ensure insecure uploads are disabled for this test.
+    $this->config('system.file')->set('allow_insecure_uploads', 0)->save();
+    $original_uri = $this->image->getFileUri();
+    /** @var \Drupal\file\FileRepositoryInterface $file_repository */
+    $file_repository = \Drupal::service('file.repository');
+    $this->image = $file_repository->move($this->image, $original_uri . '.foo.' . $this->imageExtension);
+
+    // Reset the hook counters to get rid of the 'move' we just called.
+    file_test_reset();
+
+    $extensions = $this->imageExtension;
+    $edit = [
+      'files[file_test_upload][]' => $file_system->realpath($this->image->getFileUri()),
+      'extensions' => $extensions,
+    ];
+
+    $munged_filename = $this->image->getFilename();
+    $munged_filename = substr($munged_filename, 0, strrpos($munged_filename, '.'));
+    $munged_filename .= '_.' . $this->imageExtension;
+
+    $this->drupalGet('file-test/save_upload_from_form_test');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains('For security reasons, your upload has been renamed');
+    $this->assertSession()->pageTextContains("File name is {$munged_filename}");
+    $this->assertSession()->pageTextContains("You WIN!");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'insert']);
+
+    // Test with uppercase extensions.
+    $this->image = $file_repository->move($this->image, $original_uri . '.foo2.' . $this->imageExtension);
+    // Reset the hook counters.
+    file_test_reset();
+    $extensions = $this->imageExtension;
+    $edit = [
+      'files[file_test_upload][]' => $file_system->realpath($this->image->getFileUri()),
+      'extensions' => mb_strtoupper($extensions),
+    ];
+
+    $munged_filename = $this->image->getFilename();
+    $munged_filename = substr($munged_filename, 0, strrpos($munged_filename, '.'));
+    $munged_filename .= '_.' . $this->imageExtension;
+
+    $this->drupalGet('file-test/save_upload_from_form_test');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains('For security reasons, your upload has been renamed');
+    $this->assertSession()->pageTextContains("File name is {$munged_filename}");
+    $this->assertSession()->pageTextContains("You WIN!");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'insert']);
+
+    // Ensure we don't munge files if we're allowing any extension.
+    // Reset the hook counters.
+    file_test_reset();
+
+    // Ensure we don't munge files if we're allowing any extension.
+    $edit = [
+      'files[file_test_upload][]' => $file_system->realpath($this->image->getFileUri()),
+      'allow_all_extensions' => 'empty_array',
+    ];
+
+    $this->drupalGet('file-test/save_upload_from_form_test');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextNotContains('For security reasons, your upload has been renamed');
+    $this->assertSession()->pageTextContains("File name is {$this->image->getFilename()}");
+    $this->assertSession()->pageTextContains("You WIN!");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'insert']);
+
+    // Ensure that setting $validators['file_validate_extensions'] = ['']
+    // rejects all files.
+    // Reset the hook counters.
+    file_test_reset();
+
+    $edit = [
+      'files[file_test_upload][]' => $file_system->realpath($this->image->getFileUri()),
+      'allow_all_extensions' => 'empty_string',
+    ];
+
+    $this->drupalGet('file-test/save_upload_from_form_test');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextNotContains('For security reasons, your upload has been renamed');
+    $this->assertSession()->pageTextContains("Epic upload FAIL!");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate']);
+  }
+
+  /**
+   * Tests renaming when uploading over a file that already exists.
+   */
+  public function testExistingRename(): void {
+    /** @var \Drupal\Core\File\FileSystemInterface $file_system */
+    $file_system = \Drupal::service('file_system');
+    $edit = [
+      'file_test_replace' => FileExists::Rename->name,
+      'files[file_test_upload][]' => $file_system->realpath($this->image->getFileUri()),
+    ];
+    $this->drupalGet('file-test/save_upload_from_form_test');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains("You WIN!");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'insert']);
+  }
+
+  /**
+   * Tests replacement when uploading over a file that already exists.
+   */
+  public function testExistingReplace(): void {
+    /** @var \Drupal\Core\File\FileSystemInterface $file_system */
+    $file_system = \Drupal::service('file_system');
+    $edit = [
+      'file_test_replace' => FileExists::Replace->name,
+      'files[file_test_upload][]' => $file_system->realpath($this->image->getFileUri()),
+    ];
+    $this->drupalGet('file-test/save_upload_from_form_test');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains("You WIN!");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'load', 'update']);
+  }
+
+  /**
+   * Tests for failure when uploading over a file that already exists.
+   */
+  public function testExistingError(): void {
+    /** @var \Drupal\Core\File\FileSystemInterface $file_system */
+    $file_system = \Drupal::service('file_system');
+    $edit = [
+      'file_test_replace' => FileExists::Error->name,
+      'files[file_test_upload][]' => $file_system->realpath($this->image->getFileUri()),
+    ];
+    $this->drupalGet('file-test/save_upload_from_form_test');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains("Epic upload FAIL!");
+
+    // Check that the no hooks were called while failing.
+    $this->assertFileHooksCalled([]);
+  }
+
+  /**
+   * Tests for no failures when not uploading a file.
+   */
+  public function testNoUpload(): void {
+    $this->drupalGet('file-test/save_upload_from_form_test');
+    $this->submitForm([], 'Submit');
+    $this->assertSession()->pageTextNotContains("Epic upload FAIL!");
+  }
+
+  /**
+   * Tests for log entry on failing destination.
+   */
+  public function testDrupalMovingUploadedFileError(): void {
+    // Create a directory and make it not writable.
+    $test_directory = 'test_drupal_move_uploaded_file_fail';
+    \Drupal::service('file_system')->mkdir('temporary://' . $test_directory, 0000);
+    $this->assertDirectoryExists('temporary://' . $test_directory);
+
+    /** @var \Drupal\Core\File\FileSystemInterface $file_system */
+    $file_system = \Drupal::service('file_system');
+    $edit = [
+      'file_subdir' => $test_directory,
+      'files[file_test_upload][]' => $file_system->realpath($this->image->getFileUri()),
+    ];
+
+    \Drupal::state()->set('file_test.disable_error_collection', TRUE);
+    $this->drupalGet('file-test/save_upload_from_form_test');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains('File upload error. Could not move uploaded file.');
+    $this->assertSession()->pageTextContains("Epic upload FAIL!");
+
+    // Uploading failed. Now check the log.
+    $this->drupalGet('admin/reports/dblog');
+    $this->assertSession()->statusCodeEquals(200);
+    // The full log message is in the title attribute of the link, so we cannot
+    // use ::pageTextContains() here.
+    $destination = 'temporary://' . $test_directory . '/' . $this->image->getFilename();
+    $this->assertSession()->responseContains("Upload error. Could not move uploaded file {$this->image->getFilename()} to destination {$destination}.");
+  }
+
+  /**
+   * Tests that form validation does not change error messages.
+   */
+  public function testErrorMessagesAreNotChanged(): void {
+    $error = 'An error message set before _file_save_upload_from_form()';
+
+    /** @var \Drupal\Core\File\FileSystemInterface $file_system */
+    $file_system = \Drupal::service('file_system');
+    $edit = [
+      'files[file_test_upload][]' => $file_system->realpath($this->image->getFileUri()),
+      'error_message' => $error,
+    ];
+    $this->drupalGet('file-test/save_upload_from_form_test');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains("You WIN!");
+
+    // Ensure the expected error message is present and the counts before and
+    // after calling _file_save_upload_from_form() are correct.
+    $this->assertSession()->pageTextContains($error);
+    $this->assertSession()->pageTextContains('Number of error messages before _file_save_upload_from_form(): 1');
+    $this->assertSession()->pageTextContains('Number of error messages after _file_save_upload_from_form(): 1');
+
+    // Test that error messages are preserved when an error occurs.
+    $edit = [
+      'files[file_test_upload][]' => $file_system->realpath($this->image->getFileUri()),
+      'error_message' => $error,
+      'extensions' => 'foo',
+    ];
+    $this->drupalGet('file-test/save_upload_from_form_test');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains("Epic upload FAIL!");
+
+    // Ensure the expected error message is present and the counts before and
+    // after calling _file_save_upload_from_form() are correct.
+    $this->assertSession()->pageTextContains($error);
+    $this->assertSession()->pageTextContains('Number of error messages before _file_save_upload_from_form(): 1');
+    $this->assertSession()->pageTextContains('Number of error messages after _file_save_upload_from_form(): 1');
+
+    // Test a successful upload with no messages.
+    $edit = [
+      'files[file_test_upload][]' => $file_system->realpath($this->image->getFileUri()),
+    ];
+    $this->drupalGet('file-test/save_upload_from_form_test');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains("You WIN!");
+
+    // Ensure the error message is not present and the counts before and after
+    // calling _file_save_upload_from_form() are correct.
+    $this->assertSession()->pageTextNotContains($error);
+    $this->assertSession()->pageTextContains('Number of error messages before _file_save_upload_from_form(): 0');
+    $this->assertSession()->pageTextContains('Number of error messages after _file_save_upload_from_form(): 0');
+  }
+
+  /**
+   * Tests that multiple validation errors are combined in one message.
+   */
+  public function testCombinedErrorMessages(): void {
+    $text_file = current($this->drupalGetTestFiles('text'));
+    $this->assertFileExists($text_file->uri);
+
+    /** @var \Drupal\Core\File\FileSystemInterface $file_system */
+    $file_system = \Drupal::service('file_system');
+
+    // Can't use submitForm() for set nonexistent fields.
+    $this->drupalGet('file-test/save_upload_from_form_test');
+    $client = $this->getSession()->getDriver()->getClient();
+    $submit_xpath = $this->assertSession()->buttonExists('Submit')->getXpath();
+    $form = $client->getCrawler()->filterXPath($submit_xpath)->form();
+    $edit = [
+      'is_image_file' => TRUE,
+      'extensions' => 'jpeg',
+    ];
+    $edit += $form->getPhpValues();
+    $files['files']['file_test_upload'][0] = $file_system->realpath($this->phpFile->uri);
+    $files['files']['file_test_upload'][1] = $file_system->realpath($text_file->uri);
+    $client->request($form->getMethod(), $form->getUri(), $edit, $files);
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains("Epic upload FAIL!");
+
+    // Search for combined error message followed by a formatted list of messages.
+    $this->assertSession()->responseContains('One or more files could not be uploaded.<ul>');
+  }
+
+  /**
+   * Tests highlighting of file upload field when it has an error.
+   */
+  public function testUploadFieldIsHighlighted(): void {
+    $this->assertCount(0, $this->cssSelect('input[name="files[file_test_upload][]"].error'), 'Successful file upload has no error.');
+
+    /** @var \Drupal\Core\File\FileSystemInterface $file_system */
+    $file_system = \Drupal::service('file_system');
+    $edit = [
+      'files[file_test_upload][]' => $file_system->realpath($this->image->getFileUri()),
+      'extensions' => 'foo',
+    ];
+    $this->drupalGet('file-test/save_upload_from_form_test');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains("Epic upload FAIL!");
+    $this->assertCount(1, $this->cssSelect('input[name="files[file_test_upload][]"].error'), 'File upload field has error.');
+  }
+
+}

core/modules/file/tests/src/Functional/SaveUploadTest.php

@@ -0,0 +1,902 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Functional;
+
+use Drupal\Component\Render\FormattableMarkup;
+use Drupal\Core\File\FileExists;
+use Drupal\Core\Url;
+use Drupal\file\Entity\File;
+use Drupal\Tests\TestFileCreationTrait;
+
+// cSpell:ignore TÉXT Pácê
+
+/**
+ * Tests the file_save_upload() function.
+ *
+ * @group file
+ * @group #slow
+ */
+class SaveUploadTest extends FileManagedTestBase {
+
+  use TestFileCreationTrait {
+    getTestFiles as drupalGetTestFiles;
+  }
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  protected static $modules = ['dblog', 'file_validator_test'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * An image file path for uploading.
+   *
+   * @var \Drupal\file\FileInterface
+   */
+  protected $image;
+
+  /**
+   * A PHP file path for upload security testing.
+   *
+   * @var string
+   */
+  protected $phpFile;
+
+  /**
+   * The largest file id when the test starts.
+   *
+   * @var int
+   */
+  protected $maxFidBefore;
+
+  /**
+   * Extension of the image filename.
+   *
+   * @var string
+   */
+  protected $imageExtension;
+
+  /**
+   * The user used by the test.
+   *
+   * @var \Drupal\user\Entity\User
+   */
+  protected $account;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    $this->account = $this->drupalCreateUser(['access site reports']);
+    $this->drupalLogin($this->account);
+
+    $image_files = $this->drupalGetTestFiles('image');
+    $this->image = File::create((array) current($image_files));
+
+    [, $this->imageExtension] = explode('.', $this->image->getFilename());
+    $this->assertFileExists($this->image->getFileUri());
+
+    $this->phpFile = current($this->drupalGetTestFiles('php'));
+    $this->assertFileExists($this->phpFile->uri);
+
+    $this->maxFidBefore = (int) \Drupal::entityQueryAggregate('file')
+      ->accessCheck(FALSE)
+      ->aggregate('fid', 'max')
+      ->execute()[0]['fid_max'];
+
+    // Upload with replace to guarantee there's something there.
+    $edit = [
+      'file_test_replace' => FileExists::Replace->name,
+      'files[file_test_upload]' => \Drupal::service('file_system')->realpath($this->image->getFileUri()),
+    ];
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    // Check that the success message is present.
+    $this->assertSession()->pageTextContains("You WIN!");
+
+    // Check that the correct hooks were called then clean out the hook
+    // counters.
+    $this->assertFileHooksCalled(['validate', 'insert']);
+    file_test_reset();
+  }
+
+  /**
+   * Tests the file_save_upload() function.
+   */
+  public function testNormal(): void {
+    $max_fid_after = (int) \Drupal::entityQueryAggregate('file')
+      ->accessCheck(FALSE)
+      ->aggregate('fid', 'max')
+      ->execute()[0]['fid_max'];
+    // Verify that a new file was created.
+    $this->assertGreaterThan($this->maxFidBefore, $max_fid_after);
+    $file1 = File::load($max_fid_after);
+    $this->assertInstanceOf(File::class, $file1);
+    // MIME type of the uploaded image may be either image/jpeg or image/png.
+    $this->assertEquals('image', substr($file1->getMimeType(), 0, 5), 'A MIME type was set.');
+
+    // Reset the hook counters to get rid of the 'load' we just called.
+    file_test_reset();
+
+    // Upload a second file.
+    $image2 = current($this->drupalGetTestFiles('image'));
+    $edit = ['files[file_test_upload]' => \Drupal::service('file_system')->realpath($image2->uri)];
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains("You WIN!");
+    $max_fid_after = (int) \Drupal::entityQueryAggregate('file')
+      ->accessCheck(FALSE)
+      ->aggregate('fid', 'max')
+      ->execute()[0]['fid_max'];
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'insert']);
+
+    $file2 = File::load($max_fid_after);
+    $this->assertInstanceOf(File::class, $file2);
+    // MIME type of the uploaded image may be either image/jpeg or image/png.
+    $this->assertEquals('image', substr($file2->getMimeType(), 0, 5), 'A MIME type was set.');
+
+    // Load both files using File::loadMultiple().
+    $files = File::loadMultiple([$file1->id(), $file2->id()]);
+    $this->assertTrue(isset($files[$file1->id()]), 'File was loaded successfully');
+    $this->assertTrue(isset($files[$file2->id()]), 'File was loaded successfully');
+
+    // Upload a third file to a subdirectory.
+    $image3 = current($this->drupalGetTestFiles('image'));
+    $image3_realpath = \Drupal::service('file_system')->realpath($image3->uri);
+    $dir = $this->randomMachineName();
+    $edit = [
+      'files[file_test_upload]' => $image3_realpath,
+      'file_subdir' => $dir,
+    ];
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains("You WIN!");
+    $this->assertFileExists('temporary://' . $dir . '/' . trim(\Drupal::service('file_system')->basename($image3_realpath)));
+  }
+
+  /**
+   * Tests uploading a duplicate file.
+   */
+  public function testDuplicate(): void {
+    // It should not be possible to create two managed files with the same URI.
+    $image1 = current($this->drupalGetTestFiles('image'));
+    $edit = ['files[file_test_upload]' => \Drupal::service('file_system')->realpath($image1->uri)];
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $max_fid_after = (int) \Drupal::entityQueryAggregate('file')
+      ->accessCheck(FALSE)
+      ->aggregate('fid', 'max')
+      ->execute()[0]['fid_max'];
+    $file1 = File::load($max_fid_after);
+
+    // Simulate a race condition where two files are uploaded at almost the same
+    // time, by removing the first uploaded file from disk (leaving the entry in
+    // the file_managed table) before trying to upload another file with the
+    // same name.
+    unlink(\Drupal::service('file_system')->realpath($file1->getFileUri()));
+
+    $image2 = $image1;
+    $edit = ['files[file_test_upload]' => \Drupal::service('file_system')->realpath($image2->uri)];
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    // Received a 200 response for posted test file.
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains("The file {$file1->getFileUri()} already exists. Enter a unique file URI.");
+    $max_fid_before_duplicate = $max_fid_after;
+    $max_fid_after = (int) \Drupal::entityQueryAggregate('file')
+      ->accessCheck(FALSE)
+      ->aggregate('fid', 'max')
+      ->execute()[0]['fid_max'];
+    $this->assertEquals($max_fid_before_duplicate, $max_fid_after, 'A new managed file was not created.');
+  }
+
+  /**
+   * Tests extension handling.
+   */
+  public function testHandleExtension(): void {
+    // The file being tested is a .gif which is in the default safe list
+    // of extensions to allow when the extension validator isn't used. This is
+    // implicitly tested at the testNormal() test. Here we tell
+    // file_save_upload() to only allow ".foo".
+    $extensions = 'foo';
+    $edit = [
+      'file_test_replace' => FileExists::Replace->name,
+      'files[file_test_upload]' => \Drupal::service('file_system')->realpath($this->image->getFileUri()),
+      'extensions' => $extensions,
+    ];
+
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->responseContains('Only files with the following extensions are allowed: <em class="placeholder">' . $extensions . '</em>');
+    $this->assertSession()->pageTextContains("Epic upload FAIL!");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate']);
+
+    // Reset the hook counters.
+    file_test_reset();
+
+    $extensions = 'foo ' . $this->imageExtension;
+    // Now tell file_save_upload() to allow the extension of our test image.
+    $edit = [
+      'file_test_replace' => FileExists::Replace->name,
+      'files[file_test_upload]' => \Drupal::service('file_system')->realpath($this->image->getFileUri()),
+      'extensions' => $extensions,
+    ];
+
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextNotContains("Only files with the following extensions are allowed:");
+    $this->assertSession()->pageTextContains("You WIN!");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'load', 'update']);
+
+    // Reset the hook counters.
+    file_test_reset();
+
+    // Now tell file_save_upload() to allow any extension.
+    $edit = [
+      'file_test_replace' => FileExists::Replace->name,
+      'files[file_test_upload]' => \Drupal::service('file_system')->realpath($this->image->getFileUri()),
+      'allow_all_extensions' => 'empty_array',
+    ];
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextNotContains("Only files with the following extensions are allowed:");
+    $this->assertSession()->pageTextContains("You WIN!");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'load', 'update']);
+
+    // Reset the hook counters.
+    file_test_reset();
+
+    // Now tell file_save_upload() to allow any extension and try and upload a
+    // malicious file.
+    $edit = [
+      'file_test_replace' => FileExists::Replace->name,
+      'files[file_test_upload]' => \Drupal::service('file_system')->realpath($this->phpFile->uri),
+      'allow_all_extensions' => 'empty_array',
+      'is_image_file' => FALSE,
+    ];
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->responseContains('For security reasons, your upload has been renamed to <em class="placeholder">' . $this->phpFile->filename . '_.txt' . '</em>');
+    $this->assertSession()->pageTextContains('File name is php-2.php_.txt.');
+    $this->assertSession()->pageTextContains('File MIME type is text/plain.');
+    $this->assertSession()->pageTextContains("You WIN!");
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'insert']);
+  }
+
+  /**
+   * Tests dangerous file handling.
+   */
+  public function testHandleDangerousFile(): void {
+    $config = $this->config('system.file');
+    // Allow the .php extension and make sure it gets munged and given a .txt
+    // extension for safety. Also check to make sure its MIME type was changed.
+    $edit = [
+      'file_test_replace' => FileExists::Replace->name,
+      'files[file_test_upload]' => \Drupal::service('file_system')->realpath($this->phpFile->uri),
+      'is_image_file' => FALSE,
+      'extensions' => 'php txt',
+    ];
+
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->responseContains('For security reasons, your upload has been renamed to <em class="placeholder">' . $this->phpFile->filename . '_.txt' . '</em>');
+    $this->assertSession()->pageTextContains('File name is php-2.php_.txt.');
+    $this->assertSession()->pageTextContains('File MIME type is text/plain.');
+    $this->assertSession()->pageTextContains("You WIN!");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'insert']);
+
+    // Ensure dangerous files are not renamed when insecure uploads is TRUE.
+    // Turn on insecure uploads.
+    $config->set('allow_insecure_uploads', 1)->save();
+    // Reset the hook counters.
+    file_test_reset();
+
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextNotContains('For security reasons, your upload has been renamed');
+    $this->assertSession()->pageTextContains('File name is php-2.php.');
+    $this->assertSession()->pageTextContains("You WIN!");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'insert']);
+
+    // Reset the hook counters.
+    file_test_reset();
+
+    // Even with insecure uploads allowed, the .php file should not be uploaded
+    // if it is not explicitly included in the list of allowed extensions.
+    $edit['extensions'] = 'foo';
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->responseContains('Only files with the following extensions are allowed: <em class="placeholder">' . $edit['extensions'] . '</em>');
+    $this->assertSession()->pageTextContains("Epic upload FAIL!");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate']);
+
+    // Reset the hook counters.
+    file_test_reset();
+
+    // Turn off insecure uploads, then try the same thing as above (ensure that
+    // the .php file is still rejected since it's not in the list of allowed
+    // extensions).
+    $config->set('allow_insecure_uploads', 0)->save();
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->responseContains('Only files with the following extensions are allowed: <em class="placeholder">' . $edit['extensions'] . '</em>');
+    $this->assertSession()->pageTextContains("Epic upload FAIL!");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate']);
+
+    // Reset the hook counters.
+    file_test_reset();
+
+    \Drupal::service('cache.config')->deleteAll();
+
+    $edit = [
+      'file_test_replace' => FileExists::Replace->name,
+      'files[file_test_upload]' => \Drupal::service('file_system')->realpath($this->phpFile->uri),
+      'is_image_file' => FALSE,
+      'extensions' => 'php',
+    ];
+
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains('For security reasons, your upload has been rejected.');
+    $this->assertSession()->pageTextContains('Epic upload FAIL!');
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate']);
+  }
+
+  /**
+   * Test dangerous file handling.
+   */
+  public function testHandleDotFile(): void {
+    $dot_file = $this->siteDirectory . '/.test';
+    file_put_contents($dot_file, 'This is a test');
+    $config = $this->config('system.file');
+    $edit = [
+      'file_test_replace' => FileExists::Replace->name,
+      'files[file_test_upload]' => \Drupal::service('file_system')->realpath($dot_file),
+      'is_image_file' => FALSE,
+    ];
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains('The specified file .test could not be uploaded');
+    $this->assertSession()->pageTextContains('Epic upload FAIL!');
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate']);
+
+    $edit = [
+      'file_test_replace' => FileExists::Rename->name,
+      'files[file_test_upload]' => \Drupal::service('file_system')->realpath($dot_file),
+      'is_image_file' => FALSE,
+      'allow_all_extensions' => 'empty_array',
+    ];
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains('For security reasons, your upload has been renamed to test.');
+    $this->assertSession()->pageTextContains('File name is test.');
+    $this->assertSession()->pageTextContains('You WIN!');
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'insert']);
+
+    // Reset the hook counters.
+    file_test_reset();
+
+    // Turn off insecure uploads, then try the same thing as above to ensure dot
+    // files are renamed regardless.
+    $config->set('allow_insecure_uploads', 0)->save();
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains('For security reasons, your upload has been renamed to test_0.');
+    $this->assertSession()->pageTextContains('File name is test_0.');
+    $this->assertSession()->pageTextContains('You WIN!');
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'insert']);
+
+    // Reset the hook counters.
+    file_test_reset();
+  }
+
+  /**
+   * Tests file munge handling.
+   */
+  public function testHandleFileMunge(): void {
+    // Ensure insecure uploads are disabled for this test.
+    $this->config('system.file')->set('allow_insecure_uploads', 0)->save();
+    $original_image_uri = $this->image->getFileUri();
+    /** @var \Drupal\file\FileRepositoryInterface $file_repository */
+    $file_repository = \Drupal::service('file.repository');
+    $this->image = $file_repository->move($this->image, $original_image_uri . '.foo.' . $this->imageExtension);
+
+    // Reset the hook counters to get rid of the 'move' we just called.
+    file_test_reset();
+
+    $extensions = $this->imageExtension;
+    $edit = [
+      'files[file_test_upload]' => \Drupal::service('file_system')->realpath($this->image->getFileUri()),
+      'extensions' => $extensions,
+    ];
+
+    $munged_filename = $this->image->getFilename();
+    $munged_filename = substr($munged_filename, 0, strrpos($munged_filename, '.'));
+    $munged_filename .= '_.' . $this->imageExtension;
+
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains('For security reasons, your upload has been renamed');
+    $this->assertSession()->pageTextContains("File name is $munged_filename");
+    $this->assertSession()->pageTextContains("You WIN!");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'insert']);
+
+    // Reset the hook counters.
+    file_test_reset();
+
+    // Ensure we don't munge the .foo extension if it is in the list of allowed
+    // extensions.
+    $extensions = 'foo ' . $this->imageExtension;
+    $edit = [
+      'files[file_test_upload]' => \Drupal::service('file_system')->realpath($this->image->getFileUri()),
+      'extensions' => $extensions,
+    ];
+
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextNotContains('For security reasons, your upload has been renamed');
+    $this->assertSession()->pageTextContains("File name is {$this->image->getFilename()}");
+    $this->assertSession()->pageTextContains("You WIN!");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'insert']);
+
+    // Ensure we don't munge files if we're allowing any extension.
+    $this->image = $file_repository->move($this->image, $original_image_uri . '.foo.txt.' . $this->imageExtension);
+    // Reset the hook counters.
+    file_test_reset();
+
+    $edit = [
+      'files[file_test_upload]' => \Drupal::service('file_system')->realpath($this->image->getFileUri()),
+      'allow_all_extensions' => 'empty_array',
+    ];
+
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextNotContains('For security reasons, your upload has been renamed');
+    $this->assertSession()->pageTextContains("File name is {$this->image->getFilename()}");
+    $this->assertSession()->pageTextContains("You WIN!");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'insert']);
+
+    // Test that a dangerous extension such as .php is munged even if it is in
+    // the list of allowed extensions.
+    $this->image = $file_repository->move($this->image, $original_image_uri . '.php.' . $this->imageExtension);
+    // Reset the hook counters.
+    file_test_reset();
+
+    $extensions = 'php ' . $this->imageExtension;
+    $edit = [
+      'files[file_test_upload]' => \Drupal::service('file_system')->realpath($this->image->getFileUri()),
+      'extensions' => $extensions,
+    ];
+
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains('For security reasons, your upload has been renamed');
+    $this->assertSession()->pageTextContains("File name is image-test.png_.php_.png");
+    $this->assertSession()->pageTextContains("You WIN!");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'insert']);
+
+    // Reset the hook counters.
+    file_test_reset();
+
+    // Dangerous extensions are munged even when all extensions are allowed.
+    $edit = [
+      'files[file_test_upload]' => \Drupal::service('file_system')->realpath($this->image->getFileUri()),
+      'allow_all_extensions' => 'empty_array',
+    ];
+
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains('For security reasons, your upload has been renamed');
+    $this->assertSession()->pageTextContains("File name is image-test.png_.php__0.png");
+    $this->assertSession()->pageTextContains("You WIN!");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'insert']);
+
+    // Dangerous extensions are munged if is renamed to end in .txt.
+    $this->image = $file_repository->move($this->image, $original_image_uri . '.cgi.' . $this->imageExtension . '.txt');
+    // Reset the hook counters.
+    file_test_reset();
+
+    // Dangerous extensions are munged even when all extensions are allowed.
+    $edit = [
+      'files[file_test_upload]' => \Drupal::service('file_system')->realpath($this->image->getFileUri()),
+      'allow_all_extensions' => 'empty_array',
+    ];
+
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains('For security reasons, your upload has been renamed');
+    $this->assertSession()->pageTextContains("File name is image-test.png_.cgi_.png_.txt");
+    $this->assertSession()->pageTextContains("You WIN!");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'insert']);
+
+    // Reset the hook counters.
+    file_test_reset();
+
+    // Ensure that setting $validators['FileExtension'] = ['extensions' = '']
+    // rejects all files without munging or renaming.
+    $edit = [
+      'files[file_test_upload][]' => \Drupal::service('file_system')->realpath($this->image->getFileUri()),
+      'allow_all_extensions' => 'empty_string',
+    ];
+
+    $this->drupalGet('file-test/save_upload_from_form_test');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextNotContains('For security reasons, your upload has been renamed');
+    $this->assertSession()->pageTextContains("Epic upload FAIL!");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate']);
+  }
+
+  /**
+   * Tests renaming when uploading over a file that already exists.
+   */
+  public function testExistingRename(): void {
+    $edit = [
+      'file_test_replace' => FileExists::Rename->name,
+      'files[file_test_upload]' => \Drupal::service('file_system')->realpath($this->image->getFileUri()),
+    ];
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains("You WIN!");
+    $this->assertSession()->pageTextContains('File name is image-test_0.png.');
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'insert']);
+  }
+
+  /**
+   * Tests replacement when uploading over a file that already exists.
+   */
+  public function testExistingReplace(): void {
+    $edit = [
+      'file_test_replace' => FileExists::Replace->name,
+      'files[file_test_upload]' => \Drupal::service('file_system')->realpath($this->image->getFileUri()),
+    ];
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains("You WIN!");
+    $this->assertSession()->pageTextContains('File name is image-test.png.');
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['validate', 'load', 'update']);
+  }
+
+  /**
+   * Tests for failure when uploading over a file that already exists.
+   */
+  public function testExistingError(): void {
+    $edit = [
+      'file_test_replace' => FileExists::Error->name,
+      'files[file_test_upload]' => \Drupal::service('file_system')->realpath($this->image->getFileUri()),
+    ];
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains("Epic upload FAIL!");
+
+    // Check that the no hooks were called while failing.
+    $this->assertFileHooksCalled([]);
+  }
+
+  /**
+   * Tests for no failures when not uploading a file.
+   */
+  public function testNoUpload(): void {
+    $this->drupalGet('file-test/upload');
+    $this->submitForm([], 'Submit');
+    $this->assertSession()->pageTextNotContains("Epic upload FAIL!");
+  }
+
+  /**
+   * Tests for log entry on failing destination.
+   */
+  public function testDrupalMovingUploadedFileError(): void {
+    // Create a directory and make it not writable.
+    $test_directory = 'test_drupal_move_uploaded_file_fail';
+    /** @var \Drupal\Core\File\FileSystemInterface $file_system */
+    $file_system = \Drupal::service('file_system');
+    $file_system->mkdir('temporary://' . $test_directory, 0000);
+    $this->assertDirectoryExists('temporary://' . $test_directory);
+
+    $edit = [
+      'file_subdir' => $test_directory,
+      'files[file_test_upload]' => $file_system->realpath($this->image->getFileUri()),
+    ];
+
+    \Drupal::state()->set('file_test.disable_error_collection', TRUE);
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains('File upload error. Could not move uploaded file.');
+    $this->assertSession()->pageTextContains("Epic upload FAIL!");
+
+    // Uploading failed. Now check the log.
+    $this->drupalGet('admin/reports/dblog');
+    $this->assertSession()->statusCodeEquals(200);
+    // The full log message is in the title attribute of the link, so we cannot
+    // use ::pageTextContains() here.
+    $destination = 'temporary://' . $test_directory . '/' . $this->image->getFilename();
+    $this->assertSession()->responseContains("Upload error. Could not move uploaded file {$this->image->getFilename()} to destination {$destination}.");
+  }
+
+  /**
+   * Tests that filenames containing invalid UTF-8 are rejected.
+   */
+  public function testInvalidUtf8FilenameUpload(): void {
+    $this->drupalGet('file-test/upload');
+
+    // Filename containing invalid UTF-8.
+    $filename = "x\xc0xx.gif";
+
+    $page = $this->getSession()->getPage();
+    $data = [
+      'multipart' => [
+        [
+          'name'     => 'file_test_replace',
+          'contents' => FileExists::Rename->name,
+        ],
+        [
+          'name' => 'form_id',
+          'contents' => '_file_test_form',
+        ],
+        [
+          'name' => 'form_build_id',
+          'contents' => $page->find('hidden_field_selector', ['hidden_field', 'form_build_id'])->getAttribute('value'),
+        ],
+        [
+          'name' => 'form_token',
+          'contents' => $page->find('hidden_field_selector', ['hidden_field', 'form_token'])->getAttribute('value'),
+        ],
+        [
+          'name' => 'op',
+          'contents' => 'Submit',
+        ],
+        [
+          'name'     => 'files[file_test_upload]',
+          'contents' => 'Test content',
+          'filename' => $filename,
+        ],
+      ],
+      'cookies' => $this->getSessionCookies(),
+      'http_errors' => FALSE,
+    ];
+
+    $this->assertFileDoesNotExist('temporary://' . $filename);
+    // Use Guzzle's HTTP client directly so we can POST files without having to
+    // write them to disk. Not all filesystem support writing files with invalid
+    // UTF-8 filenames.
+    $response = $this->getHttpClient()->request('POST', Url::fromUri('base:file-test/upload')->setAbsolute()->toString(), $data);
+
+    $content = (string) $response->getBody();
+    $this->htmlOutput($content);
+    $error_text = new FormattableMarkup('The file %filename could not be uploaded because the name is invalid.', ['%filename' => $filename]);
+    $this->assertStringContainsString((string) $error_text, $content);
+    $this->assertStringContainsString('Epic upload FAIL!', $content);
+    $this->assertFileDoesNotExist('temporary://' . $filename);
+  }
+
+  /**
+   * Tests the file_save_upload() function when the field is required.
+   */
+  public function testRequired(): void {
+    // Reset the hook counters to get rid of the 'load' we just called.
+    file_test_reset();
+
+    // Confirm the field is required.
+    $this->drupalGet('file-test/upload_required');
+    $this->submitForm([], 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->responseContains('field is required');
+
+    // Confirm that uploading another file works.
+    $image = current($this->drupalGetTestFiles('image'));
+    $edit = ['files[file_test_upload]' => \Drupal::service('file_system')->realpath($image->uri)];
+    $this->drupalGet('file-test/upload_required');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->responseContains('You WIN!');
+  }
+
+  /**
+   * Tests filename sanitization.
+   */
+  public function testSanitization(): void {
+    $file = $this->generateFile('TÉXT-œ', 64, 5, 'text');
+
+    $this->drupalGet('file-test/upload');
+    // Upload a file with a name with uppercase and unicode characters.
+    $edit = [
+      'files[file_test_upload]' => \Drupal::service('file_system')->realpath($file),
+      'extensions' => 'txt',
+      'is_image_file' => FALSE,
+    ];
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    // Test that the file name has not been sanitized.
+    $this->assertSession()->responseContains('File name is TÉXT-œ.txt.');
+
+    // Enable sanitization via the UI.
+    $admin = $this->createUser(['administer site configuration']);
+    $this->drupalLogin($admin);
+
+    // For now, just transliterate, with no other transformations.
+    $options = [
+      'filename_sanitization[transliterate]' => TRUE,
+      'filename_sanitization[replace_whitespace]' => FALSE,
+      'filename_sanitization[replace_non_alphanumeric]' => FALSE,
+      'filename_sanitization[deduplicate_separators]' => FALSE,
+      'filename_sanitization[lowercase]' => FALSE,
+      'filename_sanitization[replacement_character]' => '-',
+    ];
+    $this->drupalGet('admin/config/media/file-system');
+    $this->submitForm($options, 'Save configuration');
+
+    $this->drupalLogin($this->account);
+
+    // Upload a file with a name with uppercase and unicode characters.
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    // Test that the file name has been transliterated.
+    $this->assertSession()->responseContains('File name is TEXT-oe.txt.');
+    // Make sure we got a message about the rename.
+    $message = 'Your upload has been renamed to <em class="placeholder">TEXT-oe.txt</em>';
+    $this->assertSession()->responseContains($message);
+
+    // Generate another file with a name with All The Things(tm) we care about.
+    $file = $this->generateFile('S  Pácê--táb#	#--🙈', 64, 5, 'text');
+    $edit = [
+      'files[file_test_upload]' => \Drupal::service('file_system')->realpath($file),
+      'extensions' => 'txt',
+      'is_image_file' => FALSE,
+    ];
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    // Test that the file name has only been transliterated.
+    $this->assertSession()->responseContains('File name is S  Pace--tab#	#---.txt.');
+
+    // Leave transliteration on and enable whitespace replacement.
+    $this->drupalLogin($admin);
+    $options['filename_sanitization[replace_whitespace]'] = TRUE;
+    $this->drupalGet('admin/config/media/file-system');
+    $this->submitForm($options, 'Save configuration');
+    $this->drupalLogin($this->account);
+
+    // Try again with the monster filename.
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    // Test that the file name has been transliterated and whitespace replaced.
+    $this->assertSession()->responseContains('File name is S--Pace--tab#-#---.txt.');
+
+    // Leave transliteration and whitespace replacement on, replace non-alpha.
+    $this->drupalLogin($admin);
+    $options['filename_sanitization[replace_non_alphanumeric]'] = TRUE;
+    $options['filename_sanitization[replacement_character]'] = '_';
+    $this->drupalGet('admin/config/media/file-system');
+    $this->submitForm($options, 'Save configuration');
+    $this->drupalLogin($this->account);
+
+    // Try again with the monster filename.
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+
+    // Test that the file name has been transliterated, whitespace replaced with
+    // '_', and non-alphanumeric characters replaced with '_'.
+    $this->assertSession()->responseContains('File name is S__Pace--tab___--_.txt.');
+
+    // Now turn on the setting to remove duplicate separators.
+    $this->drupalLogin($admin);
+    $options['filename_sanitization[deduplicate_separators]'] = TRUE;
+    $options['filename_sanitization[replacement_character]'] = '-';
+    $this->drupalGet('admin/config/media/file-system');
+    $this->submitForm($options, 'Save configuration');
+    $this->drupalLogin($this->account);
+
+    // Try again with the monster filename.
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+
+    // Test that the file name has been transliterated, whitespace replaced,
+    // non-alphanumeric characters replaced, and duplicate separators removed.
+    $this->assertSession()->responseContains('File name is S-Pace-tab.txt.');
+
+    // Finally, check the lowercase setting.
+    $this->drupalLogin($admin);
+    $options['filename_sanitization[lowercase]'] = TRUE;
+    $this->drupalGet('admin/config/media/file-system');
+    $this->submitForm($options, 'Save configuration');
+    $this->drupalLogin($this->account);
+
+    // Generate another file since we're going to start getting collisions with
+    // previously uploaded and renamed copies.
+    $file = $this->generateFile('S  Pácê--táb#	#--🙈-2', 64, 5, 'text');
+    $edit = [
+      'files[file_test_upload]' => \Drupal::service('file_system')->realpath($file),
+      'extensions' => 'txt',
+      'is_image_file' => FALSE,
+    ];
+    $this->drupalGet('file-test/upload');
+    $this->submitForm($edit, 'Submit');
+    $this->assertSession()->statusCodeEquals(200);
+    // Make sure all the sanitization options work as intended.
+    $this->assertSession()->responseContains('File name is s-pace-tab-2.txt.');
+    // Make sure we got a message about the rename.
+    $message = 'Your upload has been renamed to <em class="placeholder">s-pace-tab-2.txt</em>';
+    $this->assertSession()->responseContains($message);
+  }
+
+}

core/modules/file/tests/src/FunctionalJavascript/AjaxFileManagedMultipleTest.php

@@ -0,0 +1,56 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\FunctionalJavascript;
+
+use Drupal\Core\Url;
+use Drupal\FunctionalJavascriptTests\WebDriverTestBase;
+use Drupal\Tests\TestFileCreationTrait;
+
+/**
+ * Tests ajax upload to managed files.
+ *
+ * @group file
+ */
+class AjaxFileManagedMultipleTest extends WebDriverTestBase {
+
+  use TestFileCreationTrait {
+    getTestFiles as drupalGetTestFiles;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['file_test', 'file', 'file_module_test'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * Tests if managed file form element works well with multiple files upload.
+   */
+  public function testMultipleFilesUpload(): void {
+    $file_system = \Drupal::service('file_system');
+    $file_storage = \Drupal::entityTypeManager()->getStorage('file');
+    $page = $this->getSession()->getPage();
+
+    $this->drupalGet(Url::fromRoute('file_module_test.managed_test', ['multiple' => TRUE]));
+
+    $paths = [];
+    foreach (array_slice($this->drupalGetTestFiles('image'), 0, 2) as $image) {
+      $paths[] = $image->filename;
+      $page->attachFileToField('files[nested_file][]', $file_system->realpath($image->uri));
+      $this->assertSession()->assertWaitOnAjaxRequest();
+    }
+
+    // Save entire form.
+    $page->pressButton('Save');
+
+    $this->assertSession()->pageTextContains('The file ids are 1,2.');
+    $this->assertCount(2, $file_storage->loadByProperties(['filename' => $paths]));
+  }
+
+}

core/modules/file/tests/src/FunctionalJavascript/FileFieldValidateTest.php

@@ -0,0 +1,58 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\FunctionalJavascript;
+
+use Drupal\FunctionalJavascriptTests\WebDriverTestBase;
+use Drupal\Tests\file\Functional\FileFieldCreationTrait;
+use Drupal\Tests\TestFileCreationTrait;
+
+/**
+ * Tests file field validation functions.
+ *
+ * Values validated include the file type, max file size, max size per node,
+ * and whether the field is required.
+ *
+ * @group file
+ */
+class FileFieldValidateTest extends WebDriverTestBase {
+
+  use FileFieldCreationTrait;
+  use TestFileCreationTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['node', 'file'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * Tests the validation message is displayed only once for ajax uploads.
+   */
+  public function testAjaxValidationMessage(): void {
+    $field_name = $this->randomMachineName();
+    $this->drupalCreateContentType(['type' => 'article', 'name' => 'Article']);
+    $this->createFileField($field_name, 'node', 'article', [], ['file_extensions' => 'txt']);
+
+    $this->drupalLogin($this->drupalCreateUser([
+      'access content',
+      'create article content',
+    ]));
+
+    $page = $this->getSession()->getPage();
+    $this->drupalGet('node/add/article');
+    $image_file = current($this->getTestFiles('image'));
+    $image_path = $this->container->get('file_system')->realpath($image_file->uri);
+    $page->attachFileToField('files[' . $field_name . '_0]', $image_path);
+    $elements = $page->waitFor(10, function () use ($page) {
+      return $page->findAll('css', '.messages--error');
+    });
+    $this->assertCount(1, $elements, 'Ajax validation messages are displayed once.');
+  }
+
+}

core/modules/file/tests/src/FunctionalJavascript/FileFieldWidgetClaroThemeTest.php

@@ -0,0 +1,107 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\FunctionalJavascript;
+
+use Drupal\Core\Url;
+
+/**
+ * Tests the widget visibility settings for the Claro theme.
+ *
+ * The widget is intentionally tested with Claro as the default theme to test
+ * the changes added in _claro_preprocess_file_and_image_widget().
+ *
+ * @see _claro_preprocess_file_and_image_widget()
+ *
+ * @group file
+ * @group #slow
+ */
+class FileFieldWidgetClaroThemeTest extends FileFieldWidgetTest {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'claro';
+
+  /**
+   * Tests that the field widget visibility settings are respected on the form.
+   */
+  public function testWidgetDefaultVisibilitySettings(): void {
+    // Set up an article node with all field storage settings set to TRUE.
+    $type_name = 'article';
+    $field_name = 'test_file_field_1';
+    $field_storage_settings = [
+      'display_field' => TRUE,
+      'display_default' => TRUE,
+    ];
+    $field_settings = [];
+    $widget_settings = [];
+    $field_storage = $this->createFileField($field_name, 'node', $type_name, $field_storage_settings, $field_settings, $widget_settings);
+
+    $page = $this->getSession()->getPage();
+    $assert_session = $this->assertSession();
+
+    $test_file = current($this->getTestFiles('text'));
+    $test_file_path = \Drupal::service('file_system')->realpath($test_file->uri);
+
+    // Fill out the form accordingly.
+    $this->drupalGet("node/add/$type_name");
+    $title = 'Fake Article Name 01';
+    $page->findField('title[0][value]')->setValue($title);
+    $page->attachFileToField('files[' . $field_name . '_0]', $test_file_path);
+    $remove_button = $assert_session->waitForElementVisible('css', '[name="' . $field_name . '_0_remove_button"]');
+    $this->assertNotNull($remove_button);
+    $type = $assert_session->fieldExists("{$field_name}[0][display]")->getAttribute('type');
+    $this->assertEquals($type, 'checkbox');
+    $assert_session->checkboxChecked("{$field_name}[0][display]");
+
+    // Now, submit the same form and ensure that value is retained.
+    $this->submitForm([], 'Save');
+    $node = $this->drupalGetNodeByTitle($title, TRUE);
+    $this->assertEquals(1, $node->get($field_name)->getValue()[0]['display'], 'The checkbox is enabled.');
+    $this->drupalGet(Url::fromRoute('entity.node.edit_form', ['node' => $node->id()]));
+    $assert_session->checkboxChecked("{$field_name}[0][display]");
+
+    // Submit the form again with the disabled value of the checkbox.
+    $this->submitForm([
+      "{$field_name}[0][display]" => FALSE,
+    ], 'Save');
+    $node = $this->drupalGetNodeByTitle($title, TRUE);
+    $this->assertEquals(0, $node->get($field_name)->getValue()[0]['display'], 'The checkbox is disabled.');
+    $this->drupalGet(Url::fromRoute('entity.node.edit_form', ['node' => $node->id()]));
+    $assert_session->checkboxNotChecked("{$field_name}[0][display]");
+
+    // Disable the field settings and ensure that the form is updated.
+    $field_storage->setSetting('display_default', FALSE);
+    $field_storage->save();
+    $page = $this->getSession()->getPage();
+    $assert_session = $this->assertSession();
+    $this->drupalGet("node/add/$type_name");
+    $title = 'Fake Article Name 02';
+    $page->findField('title[0][value]')->setValue($title);
+    $page->attachFileToField('files[' . $field_name . '_0]', $test_file_path);
+    $remove_button = $assert_session->waitForElementVisible('css', '[name="' . $field_name . '_0_remove_button"]');
+    $this->assertNotNull($remove_button);
+    $type = $assert_session->fieldExists("{$field_name}[0][display]")->getAttribute('type');
+    $this->assertEquals($type, 'checkbox');
+    $assert_session->checkboxNotChecked("{$field_name}[0][display]");
+
+    // Submit the same form and ensure that value is retained.
+    $this->submitForm([], 'Save');
+    $node = $this->drupalGetNodeByTitle($title, TRUE);
+    $this->assertEquals(0, $node->get($field_name)->getValue()[0]['display'], 'The checkbox is disabled.');
+    $this->drupalGet(Url::fromRoute('entity.node.edit_form', ['node' => $node->id()]));
+    $assert_session->checkboxNotChecked("{$field_name}[0][display]");
+
+    // Check the checkbox and ensure that it is submitted properly.
+    $this->submitForm([
+      "{$field_name}[0][display]" => TRUE,
+    ], 'Save');
+    $node = $this->drupalGetNodeByTitle($title, TRUE);
+    $this->assertEquals(1, $node->get($field_name)->getValue()[0]['display'], 'The checkbox is disabled because display_default option is marked as false.');
+    $this->drupalGet(Url::fromRoute('entity.node.edit_form', ['node' => $node->id()]));
+    $assert_session->checkboxChecked("{$field_name}[0][display]");
+  }
+
+}

core/modules/file/tests/src/FunctionalJavascript/FileFieldWidgetTest.php

@@ -0,0 +1,234 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\FunctionalJavascript;
+
+use Drupal\file\Entity\File;
+use Drupal\FunctionalJavascriptTests\WebDriverTestBase;
+use Drupal\Tests\field_ui\Traits\FieldUiTestTrait;
+use Drupal\Tests\file\Functional\FileFieldCreationTrait;
+use Drupal\Tests\TestFileCreationTrait;
+
+/**
+ * Tests the file field widget, single and multi-valued, using AJAX upload.
+ *
+ * @group file
+ */
+class FileFieldWidgetTest extends WebDriverTestBase {
+
+  use FieldUiTestTrait;
+  use FileFieldCreationTrait;
+  use TestFileCreationTrait;
+
+  /**
+   * An user with administration permissions.
+   *
+   * @var \Drupal\user\UserInterface
+   */
+  protected $adminUser;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['node', 'file', 'file_module_test', 'field_ui'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    $this->adminUser = $this->drupalCreateUser([
+      'access content',
+      'access administration pages',
+      'administer site configuration',
+      'administer users',
+      'administer permissions',
+      'administer content types',
+      'administer node fields',
+      'administer node display',
+      'administer nodes',
+      'bypass node access',
+    ]);
+    $this->drupalLogin($this->adminUser);
+    $this->drupalCreateContentType(['type' => 'article', 'name' => 'Article']);
+  }
+
+  /**
+   * Tests upload and remove buttons for multiple multi-valued File fields.
+   */
+  public function testMultiValuedWidget(): void {
+    $type_name = 'article';
+    $field_name = 'test_file_field_1';
+    $field_name2 = 'test_file_field_2';
+    $cardinality = 3;
+    $this->createFileField($field_name, 'node', $type_name, ['cardinality' => $cardinality]);
+    $this->createFileField($field_name2, 'node', $type_name, ['cardinality' => $cardinality]);
+
+    $page = $this->getSession()->getPage();
+    $assert_session = $this->assertSession();
+
+    $test_file = current($this->getTestFiles('text'));
+    $test_file_path = \Drupal::service('file_system')
+      ->realpath($test_file->uri);
+
+    $this->drupalGet("node/add/$type_name");
+    foreach ([$field_name2, $field_name] as $each_field_name) {
+      for ($delta = 0; $delta < 3; $delta++) {
+        $page->attachFileToField('files[' . $each_field_name . '_' . $delta . '][]', $test_file_path);
+        $this->assertNotNull($assert_session->waitForElementVisible('css', '[name="' . $each_field_name . '_' . $delta . '_remove_button"]'));
+        $this->assertNull($assert_session->waitForButton($each_field_name . '_' . $delta . '_upload_button'));
+      }
+    }
+
+    $num_expected_remove_buttons = 6;
+
+    foreach ([$field_name, $field_name2] as $current_field_name) {
+      // How many uploaded files for the current field are remaining.
+      $remaining = 3;
+      // Test clicking each "Remove" button. For extra robustness, test them out
+      // of sequential order. They are 0-indexed, and get renumbered after each
+      // iteration, so array(1, 1, 0) means:
+      // - First remove the 2nd file.
+      // - Then remove what is then the 2nd file (was originally the 3rd file).
+      // - Then remove the first file.
+      foreach ([1, 1, 0] as $delta) {
+        // Ensure we have the expected number of Remove buttons, and that they
+        // are numbered sequentially.
+        $buttons = $this->xpath('//input[@type="submit" and @value="Remove"]');
+        $this->assertCount($num_expected_remove_buttons, $buttons, 'There are ' . $num_expected_remove_buttons . ' "Remove" buttons displayed.');
+        foreach ($buttons as $i => $button) {
+          $key = $i >= $remaining ? $i - $remaining : $i;
+          $check_field_name = $field_name2;
+          if ($current_field_name == $field_name && $i < $remaining) {
+            $check_field_name = $field_name;
+          }
+
+          $this->assertSame($check_field_name . '_' . $key . '_remove_button', $button->getAttribute('name'));
+        }
+
+        $button_name = $current_field_name . '_' . $delta . '_remove_button';
+        $remove_button = $assert_session->waitForButton($button_name);
+        $remove_button->click();
+
+        $num_expected_remove_buttons--;
+        $remaining--;
+
+        // Ensure an "Upload" button for the current field is displayed with the
+        // correct name.
+        $upload_button_name = $current_field_name . '_' . $remaining . '_upload_button';
+        $this->assertNotNull($assert_session->waitForButton($upload_button_name));
+        $button = $this->assertSession()->buttonExists($upload_button_name);
+        $this->assertSame('Upload', $button->getValue());
+
+        // Verify that after removing a file, only one "Upload" button for each
+        // possible field is displayed.
+        $expected = $current_field_name == $field_name ? 1 : 2;
+        $this->assertSession()->elementsCount('xpath', '//input[@type="submit" and @value="Upload"]', $expected);
+      }
+    }
+  }
+
+  /**
+   * Tests uploading and remove buttons for a single-valued File field.
+   */
+  public function testSingleValuedWidget(): void {
+    $type_name = 'article';
+    $field_name = 'test_file_field_1';
+    $cardinality = 1;
+    $this->createFileField($field_name, 'node', $type_name, ['cardinality' => $cardinality]);
+
+    $page = $this->getSession()->getPage();
+    $assert_session = $this->assertSession();
+
+    $test_file = current($this->getTestFiles('text'));
+    $test_file_path = \Drupal::service('file_system')
+      ->realpath($test_file->uri);
+
+    $this->drupalGet("node/add/$type_name");
+
+    $page->findField('title[0][value]')->setValue($this->randomString());
+
+    $page->attachFileToField('files[' . $field_name . '_0]', $test_file_path);
+    $remove_button = $assert_session->waitForElementVisible('css', '[name="' . $field_name . '_0_remove_button"]');
+    $this->assertNotNull($remove_button);
+    $remove_button->click();
+    $upload_field = $assert_session->waitForElementVisible('css', 'input[type="file"]');
+    $this->assertNotEmpty($upload_field);
+    $page->attachFileToField('files[' . $field_name . '_0]', $test_file_path);
+    $remove_button = $assert_session->waitForElementVisible('css', '[name="' . $field_name . '_0_remove_button"]');
+    $this->assertNotNull($remove_button);
+    $page->pressButton('Save');
+    $page->hasContent($test_file->name);
+
+    // Create a new node and try to upload a file with an invalid extension.
+    $test_image = current($this->getTestFiles('image'));
+    $test_image_path = \Drupal::service('file_system')
+      ->realpath($test_image->uri);
+
+    $this->drupalGet("node/add/$type_name");
+
+    $page->findField('title[0][value]')->setValue($this->randomString());
+    $page->attachFileToField('files[' . $field_name . '_0]', $test_image_path);
+    $messages = $assert_session->waitForElementVisible('css', '.file-upload-js-error');
+    $this->assertEquals('The selected file image-test.png cannot be uploaded. Only files with the following extensions are allowed: txt.', $messages->getText());
+    // Make sure the error disappears when a valid file is uploaded.
+    $page->attachFileToField('files[' . $field_name . '_0]', $test_file_path);
+    $remove_button = $assert_session->waitForElementVisible('css', '[name="' . $field_name . '_0_remove_button"]');
+    $this->assertNotEmpty($remove_button);
+    $this->assertEmpty($this->cssSelect('.file-upload-js-error'));
+  }
+
+  /**
+   * Tests uploading more files than allowed at once.
+   */
+  public function testUploadingMoreFilesThanAllowed(): void {
+    $type_name = 'article';
+    $field_name = 'test_file_field_1';
+    $cardinality = 2;
+    $this->createFileField($field_name, 'node', $type_name, ['cardinality' => $cardinality]);
+
+    $web_driver = $this->getSession()->getDriver();
+    $file_system = \Drupal::service('file_system');
+
+    $files = array_slice($this->getTestFiles('text'), 0, 3);
+    $real_paths = [];
+    foreach ($files as $file) {
+      $real_paths[] = $file_system->realpath($file->uri);
+    }
+    $remote_paths = [];
+    foreach ($real_paths as $path) {
+      $remote_paths[] = $web_driver->uploadFileAndGetRemoteFilePath($path);
+    }
+
+    // Tests that uploading multiple remote files works with remote path.
+    $this->drupalGet("node/add/$type_name");
+    $multiple_field = $this->getSession()->getPage()->findField('files[test_file_field_1_0][]');
+    $multiple_field->setValue(implode("\n", $remote_paths));
+    $this->assertSession()->assertWaitOnAjaxRequest();
+    $this->assertSession()->pageTextContains("Field {$field_name} can only hold {$cardinality} values but there were 3 uploaded. The following files have been omitted as a result: text-2.txt.");
+  }
+
+  /**
+   * Retrieves a sample file of the specified type.
+   *
+   * @return \Drupal\file\FileInterface
+   *   The new unsaved file entity.
+   */
+  public function getTestFile($type_name, $size = NULL) {
+    // Get a file to upload.
+    $file = current($this->getTestFiles($type_name, $size));
+
+    // Add a filesize property to files as would be read by
+    // \Drupal\file\Entity\File::load().
+    $file->filesize = filesize($file->uri);
+
+    return File::create((array) $file);
+  }
+
+}

core/modules/file/tests/src/FunctionalJavascript/FileManagedFileElementTest.php

@@ -0,0 +1,121 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\FunctionalJavascript;
+
+use Drupal\FunctionalJavascriptTests\WebDriverTestBase;
+
+/**
+ * Tests the 'managed_file' element type.
+ *
+ * @group file
+ */
+class FileManagedFileElementTest extends WebDriverTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['node', 'file', 'file_module_test', 'field_ui'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * A user with administration permissions.
+   *
+   * @var \Drupal\user\UserInterface
+   */
+  protected $adminUser;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    $this->adminUser = $this->drupalCreateUser([
+      'access content',
+      'access administration pages',
+      'administer site configuration',
+      'administer users',
+      'administer permissions',
+      'administer content types',
+      'administer node fields',
+      'administer node display',
+      'administer nodes',
+      'bypass node access',
+    ]);
+    $this->drupalLogin($this->adminUser);
+    $this->drupalCreateContentType(['type' => 'article', 'name' => 'Article']);
+  }
+
+  /**
+   * Tests the managed_file element type.
+   */
+  public function testManagedFile(): void {
+    // Perform the tests with all permutations of $form['#tree'],
+    // $element['#extended'], and $element['#multiple'].
+    $filename = \Drupal::service('file_system')->tempnam('temporary://', "testManagedFile") . '.txt';
+    file_put_contents($filename, $this->randomString(128));
+    foreach ([0, 1] as $tree) {
+      foreach ([0, 1] as $extended) {
+        foreach ([0, 1] as $multiple) {
+          $path = 'file/test/' . $tree . '/' . $extended . '/' . $multiple;
+          $input_base_name = $tree ? 'nested_file' : 'file';
+          $file_field_name = $multiple ? 'files[' . $input_base_name . '][]' : 'files[' . $input_base_name . ']';
+
+          // Now, test the Upload and Remove buttons, with Ajax.
+          // Upload, then Submit.
+          $last_fid_prior = $this->getLastFileId();
+          $this->drupalGet($path);
+          $this->getSession()->getPage()->attachFileToField($file_field_name, $this->container->get('file_system')->realpath($filename));
+          $uploaded_file = $this->assertSession()->waitForElement('css', '.file--mime-text-plain');
+          $this->assertNotEmpty($uploaded_file);
+          $last_fid = $this->getLastFileId();
+          $this->assertGreaterThan($last_fid_prior, $last_fid, 'New file got uploaded.');
+          $this->submitForm([], 'Save');
+
+          // Remove, then Submit.
+          $remove_button_title = $multiple ? 'Remove selected' : 'Remove';
+          $this->drupalGet($path . '/' . $last_fid);
+          if ($multiple) {
+            $selected_checkbox = ($tree ? 'nested[file]' : 'file') . '[file_' . $last_fid . '][selected]';
+            $this->getSession()->getPage()->checkField($selected_checkbox);
+          }
+          $this->getSession()->getPage()->pressButton($remove_button_title);
+          $this->assertSession()->assertWaitOnAjaxRequest();
+          $this->submitForm([], 'Save');
+          $this->assertSession()->pageTextContains('The file ids are .');
+
+          // Upload, then Remove, then Submit.
+          $this->drupalGet($path);
+          $this->getSession()->getPage()->attachFileToField($file_field_name, $this->container->get('file_system')->realpath($filename));
+          $uploaded_file = $this->assertSession()->waitForElement('css', '.file--mime-text-plain');
+          $this->assertNotEmpty($uploaded_file);
+          if ($multiple) {
+            $selected_checkbox = ($tree ? 'nested[file]' : 'file') . '[file_' . $this->getLastFileId() . '][selected]';
+            $this->getSession()->getPage()->checkField($selected_checkbox);
+          }
+          $this->getSession()->getPage()->pressButton($remove_button_title);
+          $this->assertSession()->assertWaitOnAjaxRequest();
+
+          $this->submitForm([], 'Save');
+          $this->assertSession()->pageTextContains('The file ids are .');
+        }
+      }
+    }
+  }
+
+  /**
+   * Retrieves the fid of the last inserted file.
+   */
+  protected function getLastFileId() {
+    return (int) \Drupal::entityQueryAggregate('file')
+      ->accessCheck(FALSE)
+      ->aggregate('fid', 'max')
+      ->execute()[0]['fid_max'];
+  }
+
+}

core/modules/file/tests/src/FunctionalJavascript/MaximumFileSizeExceededUploadTest.php

@@ -0,0 +1,129 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\FunctionalJavascript;
+
+use Drupal\Component\Utility\Bytes;
+use Drupal\FunctionalJavascriptTests\WebDriverTestBase;
+use Drupal\Tests\TestFileCreationTrait;
+use Drupal\Tests\file\Functional\FileFieldCreationTrait;
+
+/**
+ * Tests uploading a file that exceeds the maximum file size.
+ *
+ * @group file
+ */
+class MaximumFileSizeExceededUploadTest extends WebDriverTestBase {
+
+  use FileFieldCreationTrait;
+  use TestFileCreationTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['node', 'file'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * The file system service.
+   *
+   * @var \Drupal\Core\File\FileSystemInterface
+   */
+  protected $fileSystem;
+
+  /**
+   * A test user.
+   *
+   * @var \Drupal\user\UserInterface
+   */
+  protected $user;
+
+  /**
+   * The original value of the 'display_errors' PHP configuration option.
+   *
+   * @todo Remove this when issue #2905597 is fixed.
+   * @see https://www.drupal.org/node/2905597
+   *
+   * @var string
+   */
+  protected $originalDisplayErrorsValue;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+
+    $this->fileSystem = $this->container->get('file_system');
+
+    // Create the Article node type.
+    $this->drupalCreateContentType(['type' => 'article', 'name' => 'Article']);
+
+    // Attach a file field to the node type.
+    $field_settings = ['file_extensions' => 'bin txt'];
+    $this->createFileField('field_file', 'node', 'article', [], $field_settings);
+
+    // Log in as a content author who can create Articles.
+    $this->user = $this->drupalCreateUser([
+      'access content',
+      'create article content',
+    ]);
+    $this->drupalLogin($this->user);
+
+    // Disable the displaying of errors, so that the AJAX responses are not
+    // contaminated with error messages about exceeding the maximum POST size.
+    // @todo Remove this when issue #2905597 is fixed.
+    // @see https://www.drupal.org/node/2905597
+    $this->originalDisplayErrorsValue = ini_set('display_errors', '0');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function tearDown(): void {
+    // Restore the displaying of errors to the original value.
+    // @todo Remove this when issue #2905597 is fixed.
+    // @see https://www.drupal.org/node/2905597
+    ini_set('display_errors', $this->originalDisplayErrorsValue);
+
+    parent::tearDown();
+  }
+
+  /**
+   * Tests that uploading files exceeding maximum size are handled correctly.
+   */
+  public function testUploadFileExceedingMaximumFileSize(): void {
+    $session = $this->getSession();
+
+    // Create a test file that exceeds the maximum POST size with 1 kilobyte.
+    $post_max_size = (int) Bytes::toNumber(ini_get('post_max_size'));
+    $invalid_file = 'public://exceeding_post_max_size.bin';
+    $file = fopen($invalid_file, 'wb');
+    fseek($file, $post_max_size + 1024);
+    fwrite($file, '0');
+    fclose($file);
+
+    // Go to the node creation form and try to upload the test file.
+    $this->drupalGet('node/add/article');
+    $page = $session->getPage();
+    $page->attachFileToField("files[field_file_0]", $this->fileSystem->realpath($invalid_file));
+
+    // An error message should appear informing the user that the file exceeded
+    // the maximum file size. The error message includes the actual file size
+    // limit which depends on the current environment, so we check for a part
+    // of the message.
+    $this->assertSession()->statusMessageContainsAfterWait('An unrecoverable error occurred. The uploaded file likely exceeded the maximum file size', 'error');
+
+    // Now upload a valid file and check that the error message disappears.
+    $valid_file = $this->generateFile('not_exceeding_post_max_size', 8, 8);
+    $page->attachFileToField("files[field_file_0]", $this->fileSystem->realpath($valid_file));
+    $this->assertSession()->waitForElement('named', ['id_or_name', 'field_file_0_remove_button']);
+    $this->assertSession()->statusMessageNotExistsAfterWait('error');
+  }
+
+}

core/modules/file/tests/src/Kernel/AccessTest.php

@@ -0,0 +1,192 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel;
+
+use Drupal\file\Entity\File;
+use Drupal\KernelTests\KernelTestBase;
+use Drupal\Tests\TestFileCreationTrait;
+use Drupal\Tests\user\Traits\UserCreationTrait;
+use Drupal\user\Entity\User;
+
+/**
+ * Tests for the File access control.
+ *
+ * @group file
+ */
+class AccessTest extends KernelTestBase {
+
+  use UserCreationTrait;
+  use TestFileCreationTrait;
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  protected static $modules = ['file', 'system', 'user'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+
+    $this->installEntitySchema('file');
+    $this->installEntitySchema('user');
+    $this->installSchema('file', ['file_usage']);
+  }
+
+  /**
+   * Tests 'update' and 'delete' access to file entities.
+   */
+  public function testFileAccess(): void {
+    // Create a user so the tested users do not have the magic ID of user 1.
+    $this->createUser();
+
+    $user_any = $this->createUser([
+      'delete any file',
+    ]);
+    $this->assertGreaterThan(1, (int) $user_any->id());
+
+    $user_own = $this->createUser([
+      'delete own files',
+    ]);
+
+    $test_files = $this->getTestFiles('text');
+    $file1 = File::create((array) $test_files[0]);
+    $file1->set('uid', $user_any->id());
+    $file1->save();
+    $file2 = File::create((array) $test_files[1]);
+    $file2->set('uid', $user_own->id());
+    $file2->save();
+
+    // User with "* any file" permissions should delete all files and update
+    // their own.
+    $this->assertTrue($file1->access('delete', $user_any));
+    $this->assertTrue($file1->access('update', $user_any));
+    $this->assertTrue($file2->access('delete', $user_any));
+    $this->assertFalse($file2->access('update', $user_any));
+
+    // User with "* own files" permissions should access only own files.
+    $this->assertFalse($file1->access('delete', $user_own));
+    $this->assertFalse($file1->access('update', $user_own));
+    $this->assertTrue($file2->access('delete', $user_own));
+    $this->assertTrue($file2->access('update', $user_own));
+
+    // Ensure cacheability metadata is correct.
+    /** @var \Drupal\Core\Access\AccessResult $access */
+    $access = $file2->access('delete', $user_any, TRUE);
+    $this->assertSame(['user.permissions'], $access->getCacheContexts());
+    $this->assertSame([], $access->getCacheTags());
+    /** @var \Drupal\Core\Access\AccessResult $access */
+    $access = $file2->access('delete', $user_own, TRUE);
+    $this->assertSame(['user.permissions', 'user'], $access->getCacheContexts());
+    $this->assertSame(['file:2'], $access->getCacheTags());
+    /** @var \Drupal\Core\Access\AccessResult $access */
+    $access = $file2->access('update', $user_any, TRUE);
+    $this->assertSame([], $access->getCacheContexts());
+    $this->assertSame([], $access->getCacheTags());
+    /** @var \Drupal\Core\Access\AccessResult $access */
+    $access = $file2->access('update', $user_own, TRUE);
+    $this->assertSame([], $access->getCacheContexts());
+    $this->assertSame([], $access->getCacheTags());
+
+    // User without permissions should not be able to delete files even if they
+    // are the owner.
+    $user_none = $this->createUser();
+    $file3 = File::create([
+      'uid' => $user_none->id(),
+      'filename' => 'druplicon.txt',
+      'filemime' => 'text/plain',
+    ]);
+    $this->assertFalse($file3->access('delete', $user_none));
+    $this->assertTrue($file3->access('update', $user_none));
+
+    // Create a file with no user entity.
+    $file4 = File::create([
+      'filename' => 'druplicon.txt',
+      'filemime' => 'text/plain',
+    ]);
+    $this->assertFalse($file4->access('delete', $user_own));
+    $this->assertFalse($file4->access('update', $user_own));
+    $this->assertTrue($file4->access('delete', $user_any));
+    $this->assertFalse($file4->access('update', $user_any));
+  }
+
+  /**
+   * Tests file entity field access.
+   *
+   * @see \Drupal\file\FileAccessControlHandler::checkFieldAccess()
+   */
+  public function testCheckFieldAccess(): void {
+    $this->setUpCurrentUser();
+    /** @var \Drupal\file\FileInterface $file */
+    $file = File::create([
+      'uri' => 'public://test.png',
+    ]);
+    // While creating a file entity access will be allowed for create-only
+    // fields.
+    $this->assertTrue($file->get('uri')->access('edit'));
+    $this->assertTrue($file->get('filemime')->access('edit'));
+    $this->assertTrue($file->get('filesize')->access('edit'));
+    // Access to the status field is denied whilst creating a file entity.
+    $this->assertFalse($file->get('status')->access('edit'));
+    $file->save();
+    // After saving the entity is no longer new and, therefore, access to
+    // create-only fields and the status field will be denied.
+    $this->assertFalse($file->get('uri')->access('edit'));
+    $this->assertFalse($file->get('filemime')->access('edit'));
+    $this->assertFalse($file->get('filesize')->access('edit'));
+    $this->assertFalse($file->get('status')->access('edit'));
+  }
+
+  /**
+   * Tests create access is always denied even for user 1.
+   *
+   * @see \Drupal\file\FileAccessControlHandler::checkCreateAccess()
+   */
+  public function testCreateAccess(): void {
+    $user1 = $this->createUser([
+      'delete own files',
+    ]);
+
+    $this->assertSame('1', $user1->id());
+
+    $file = File::create([
+      'uid' => $user1->id(),
+      'filename' => 'druplicon.txt',
+      'filemime' => 'text/plain',
+    ]);
+    $this->assertFalse($file->access('create'));
+
+    \Drupal::currentUser()->setAccount($user1);
+    $this->assertFalse($file->access('create'));
+  }
+
+  /**
+   * Tests cacheability metadata.
+   */
+  public function testFileCacheability(): void {
+    $file = File::create([
+      'filename' => 'green-scarf',
+      'uri' => 'private://green-scarf',
+      'filemime' => 'text/plain',
+    ]);
+    $file->setPermanent();
+    $file->save();
+    \Drupal::service('session')->set('anonymous_allowed_file_ids', [$file->id() => $file->id()]);
+
+    $account = User::getAnonymousUser();
+    $file->setOwnerId($account->id())->save();
+    $this->assertSame(['session', 'user'], $file->access('view', $account, TRUE)->getCacheContexts());
+    $this->assertSame(['session', 'user'], $file->access('download', $account, TRUE)->getCacheContexts());
+
+    $account = $this->createUser();
+    $file->setOwnerId($account->id())->save();
+    $this->assertSame(['user'], $file->access('view', $account, TRUE)->getCacheContexts());
+    $this->assertSame(['user'], $file->access('download', $account, TRUE)->getCacheContexts());
+  }
+
+}

core/modules/file/tests/src/Kernel/ComputedFileUrlTest.php

@@ -0,0 +1,93 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel;
+
+use Drupal\Core\Field\FieldItemInterface;
+use Drupal\Core\TypedData\DataDefinitionInterface;
+use Drupal\file\FileInterface;
+use Drupal\file\ComputedFileUrl;
+use Drupal\KernelTests\KernelTestBase;
+
+/**
+ * @coversDefaultClass \Drupal\file\ComputedFileUrl
+ *
+ * @group file
+ */
+class ComputedFileUrlTest extends KernelTestBase {
+
+  /**
+   * The test URL to use.
+   *
+   * @var string
+   */
+  protected $testUrl = 'public://druplicon.txt';
+
+  /**
+   * @covers ::getValue
+   */
+  public function testGetValue(): void {
+    $entity = $this->prophesize(FileInterface::class);
+    $entity->getFileUri()
+      ->willReturn($this->testUrl);
+
+    $parent = $this->prophesize(FieldItemInterface::class);
+    $parent->getEntity()
+      ->shouldBeCalledTimes(2)
+      ->willReturn($entity->reveal());
+
+    $definition = $this->prophesize(DataDefinitionInterface::class);
+
+    $typed_data = new ComputedFileUrl($definition->reveal(), $this->randomMachineName(), $parent->reveal());
+
+    $expected = base_path() . $this->siteDirectory . '/files/druplicon.txt';
+
+    $this->assertSame($expected, $typed_data->getValue());
+    // Do this a second time to confirm the same value is returned but the value
+    // isn't retrieved from the parent entity again.
+    $this->assertSame($expected, $typed_data->getValue());
+  }
+
+  /**
+   * @covers ::setValue
+   */
+  public function testSetValue(): void {
+    $name = $this->randomMachineName();
+    $parent = $this->prophesize(FieldItemInterface::class);
+    $parent->onChange($name)
+      ->shouldBeCalled();
+
+    $definition = $this->prophesize(DataDefinitionInterface::class);
+    $typed_data = new ComputedFileUrl($definition->reveal(), $name, $parent->reveal());
+
+    // Setting the value explicitly should mean the parent entity is never
+    // called into.
+    $typed_data->setValue($this->testUrl);
+
+    $this->assertSame($this->testUrl, $typed_data->getValue());
+    // Do this a second time to confirm the same value is returned but the value
+    // isn't retrieved from the parent entity again.
+    $this->assertSame($this->testUrl, $typed_data->getValue());
+  }
+
+  /**
+   * @covers ::setValue
+   */
+  public function testSetValueNoNotify(): void {
+    $name = $this->randomMachineName();
+    $parent = $this->prophesize(FieldItemInterface::class);
+    $parent->onChange($name)
+      ->shouldNotBeCalled();
+
+    $definition = $this->prophesize(DataDefinitionInterface::class);
+    $typed_data = new ComputedFileUrl($definition->reveal(), $name, $parent->reveal());
+
+    // Setting the value should explicitly should mean the parent entity is
+    // never called into.
+    $typed_data->setValue($this->testUrl, FALSE);
+
+    $this->assertSame($this->testUrl, $typed_data->getValue());
+  }
+
+}

core/modules/file/tests/src/Kernel/CopyTest.php

@@ -0,0 +1,221 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel;
+
+use Drupal\Core\Entity\EntityStorageException;
+use Drupal\Core\Entity\EntityTypeManager;
+use Drupal\Core\File\Exception\FileExistsException;
+use Drupal\Core\File\Exception\InvalidStreamWrapperException;
+use Drupal\Core\File\FileExists;
+use Drupal\file\Entity\File;
+use Drupal\file\FileRepository;
+
+/**
+ * Tests the file copy function.
+ *
+ * @coversDefaultClass \Drupal\file\FileRepository
+ * @group file
+ */
+class CopyTest extends FileManagedUnitTestBase {
+
+  /**
+   * The file repository service under test.
+   *
+   * @var \Drupal\file\FileRepository
+   */
+  protected $fileRepository;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    $this->fileRepository = $this->container->get('file.repository');
+  }
+
+  /**
+   * Tests file copying in the normal, base case.
+   *
+   * @covers ::copy
+   */
+  public function testNormal(): void {
+    $contents = $this->randomMachineName(10);
+    $source = $this->createFile(NULL, $contents);
+    $desired_uri = 'public://' . $this->randomMachineName();
+
+    // Clone the object so we don't have to worry about the function changing
+    // our reference copy.
+    $result = $this->fileRepository->copy(clone $source, $desired_uri, FileExists::Error);
+
+    // Check the return status and that the contents changed.
+    $this->assertNotFalse($result, 'File copied successfully.');
+    $this->assertEquals($contents, file_get_contents($result->getFileUri()), 'Contents of file were copied correctly.');
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['copy', 'insert']);
+
+    $this->assertDifferentFile($source, $result);
+    $this->assertEquals($result->getFileUri(), $desired_uri, 'The copied file entity has the desired filepath.');
+    $this->assertFileExists($source->getFileUri());
+    $this->assertFileExists($result->getFileUri());
+
+    // Reload the file from the database and check that the changes were
+    // actually saved.
+    $this->assertFileUnchanged($result, File::load($result->id()));
+  }
+
+  /**
+   * Tests renaming when copying over a file that already exists.
+   *
+   * @covers ::copy
+   */
+  public function testExistingRename(): void {
+    // Setup a file to overwrite.
+    $contents = $this->randomMachineName(10);
+    $source = $this->createFile(NULL, $contents);
+    $target = $this->createFile();
+    $this->assertDifferentFile($source, $target);
+
+    // Clone the object so we don't have to worry about the function changing
+    // our reference copy.
+    $result = $this->fileRepository->copy(clone $source, $target->getFileUri(), FileExists::Rename);
+
+    // Check the return status and that the contents changed.
+    $this->assertNotFalse($result, 'File copied successfully.');
+    $this->assertEquals($contents, file_get_contents($result->getFileUri()), 'Contents of file were copied correctly.');
+    $this->assertNotEquals($source->getFileUri(), $result->getFileUri(), 'Returned file path has changed from the original.');
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['copy', 'insert']);
+
+    // Load all the affected files to check the changes that actually made it
+    // to the database.
+    $loaded_source = File::load($source->id());
+    $loaded_target = File::load($target->id());
+    $loaded_result = File::load($result->id());
+
+    // Verify that the source file wasn't changed.
+    $this->assertFileUnchanged($source, $loaded_source);
+
+    // Verify that what was returned is what's in the database.
+    $this->assertFileUnchanged($result, $loaded_result);
+
+    // Make sure we end up with three distinct files afterwards.
+    $this->assertDifferentFile($loaded_source, $loaded_target);
+    $this->assertDifferentFile($loaded_target, $loaded_result);
+    $this->assertDifferentFile($loaded_source, $loaded_result);
+  }
+
+  /**
+   * Tests replacement when copying over a file that already exists.
+   *
+   * @covers ::copy
+   */
+  public function testExistingReplace(): void {
+    // Setup a file to overwrite.
+    $contents = $this->randomMachineName(10);
+    $source = $this->createFile(NULL, $contents);
+    $target = $this->createFile();
+    $this->assertDifferentFile($source, $target);
+
+    // Clone the object so we don't have to worry about the function changing
+    // our reference copy.
+    $result = $this->fileRepository->copy(clone $source, $target->getFileUri(), FileExists::Replace);
+
+    // Check the return status and that the contents changed.
+    $this->assertNotFalse($result, 'File copied successfully.');
+    $this->assertEquals($contents, file_get_contents($result->getFileUri()), 'Contents of file were overwritten.');
+    $this->assertDifferentFile($source, $result);
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['load', 'copy', 'update']);
+
+    // Load all the affected files to check the changes that actually made it
+    // to the database.
+    $loaded_source = File::load($source->id());
+    $loaded_target = File::load($target->id());
+    $loaded_result = File::load($result->id());
+
+    // Verify that the source file wasn't changed.
+    $this->assertFileUnchanged($source, $loaded_source);
+
+    // Verify that what was returned is what's in the database.
+    $this->assertFileUnchanged($result, $loaded_result);
+
+    // Target file was reused for the result.
+    $this->assertFileUnchanged($loaded_target, $loaded_result);
+  }
+
+  /**
+   * Tests that copying over an existing file fails when instructed to do so.
+   *
+   * @covers ::copy
+   */
+  public function testExistingError(): void {
+    $contents = $this->randomMachineName(10);
+    $source = $this->createFile();
+    $target = $this->createFile(NULL, $contents);
+    $this->assertDifferentFile($source, $target);
+
+    // Clone the object so we don't have to worry about the function changing
+    // our reference copy.
+    try {
+      $result = $this->fileRepository->copy(clone $source, $target->getFileUri(), FileExists::Error);
+      $this->fail('expected FileExistsException');
+    }
+    // FileExistsException is a subclass of FileException.
+    catch (FileExistsException $e) {
+      // expected exception.
+      $this->assertStringContainsString("could not be copied because a file by that name already exists in the destination directory", $e->getMessage());
+    }
+    // Check the contents were not changed.
+    $this->assertEquals($contents, file_get_contents($target->getFileUri()), 'Contents of file were not altered.');
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled([]);
+
+    $this->assertFileUnchanged($source, File::load($source->id()));
+    $this->assertFileUnchanged($target, File::load($target->id()));
+  }
+
+  /**
+   * Tests for an invalid stream wrapper.
+   *
+   * @covers ::copy
+   */
+  public function testInvalidStreamWrapper(): void {
+    $this->expectException(InvalidStreamWrapperException::class);
+    $this->expectExceptionMessage('Invalid stream wrapper: foo://');
+    $source = $this->createFile();
+    $this->fileRepository->copy($source, 'foo://');
+  }
+
+  /**
+   * Tests for entity storage exception.
+   *
+   * @covers ::copy
+   */
+  public function testEntityStorageException(): void {
+    /** @var \Drupal\Core\Entity\EntityTypeManager $entityTypeManager */
+    $entityTypeManager = $this->prophesize(EntityTypeManager::class);
+    $entityTypeManager->getStorage('file')
+      ->willThrow(EntityStorageException::class);
+
+    $fileRepository = new FileRepository(
+      $this->container->get('file_system'),
+      $this->container->get('stream_wrapper_manager'),
+      $entityTypeManager->reveal(),
+      $this->container->get('module_handler'),
+      $this->container->get('file.usage'),
+      $this->container->get('current_user')
+    );
+
+    $this->expectException(EntityStorageException::class);
+    $source = $this->createFile();
+    $target = $this->createFile();
+    $fileRepository->copy($source, $target->getFileUri(), FileExists::Replace);
+  }
+
+}

core/modules/file/tests/src/Kernel/DeleteTest.php

@@ -0,0 +1,106 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel;
+
+use Drupal\Core\Database\Database;
+use Drupal\file\Entity\File;
+
+/**
+ * Tests the file delete function.
+ *
+ * @group file
+ */
+class DeleteTest extends FileManagedUnitTestBase {
+
+  /**
+   * Tries deleting a normal file (as opposed to a directory, symlink, etc).
+   */
+  public function testUnused(): void {
+    $file = $this->createFile();
+
+    // Check that deletion removes the file and database record.
+    $this->assertFileExists($file->getFileUri());
+    $file->delete();
+    $this->assertFileHooksCalled(['delete']);
+    $this->assertFileDoesNotExist($file->getFileUri());
+    $this->assertNull(File::load($file->id()), 'File was removed from the database.');
+  }
+
+  /**
+   * Tries deleting a file that is in use.
+   */
+  public function testInUse(): void {
+    // This test expects unused managed files to be marked as a temporary file
+    // and then deleted up by file_cron().
+    $this->config('file.settings')
+      ->set('make_unused_managed_files_temporary', TRUE)
+      ->save();
+    $file = $this->createFile();
+    $file_usage = $this->container->get('file.usage');
+    $file_usage->add($file, 'testing', 'test', 1);
+    $file_usage->add($file, 'testing', 'test', 1);
+
+    $file_usage->delete($file, 'testing', 'test', 1);
+    $usage = $file_usage->listUsage($file);
+    $this->assertEquals([1 => 1], $usage['testing']['test'], 'Test file is still in use.');
+    $this->assertFileExists($file->getFileUri());
+    $this->assertNotEmpty(File::load($file->id()), 'File still exists in the database.');
+
+    // Clear out the call to hook_file_load().
+    file_test_reset();
+
+    $file_usage->delete($file, 'testing', 'test', 1);
+    $usage = $file_usage->listUsage($file);
+    $this->assertFileHooksCalled(['load', 'update']);
+    $this->assertEmpty($usage, 'File usage data was removed.');
+    $this->assertFileExists($file->getFileUri());
+    $file = File::load($file->id());
+    $this->assertNotEmpty($file, 'File still exists in the database.');
+    $this->assertTrue($file->isTemporary(), 'File is temporary.');
+    file_test_reset();
+
+    // Call file_cron() to clean up the file. Make sure the changed timestamp
+    // of the file is older than the system.file.temporary_maximum_age
+    // configuration value. We use an UPDATE statement because using the API
+    // would set the timestamp.
+    Database::getConnection()->update('file_managed')
+      ->fields([
+        'changed' => \Drupal::time()->getRequestTime() - ($this->config('system.file')->get('temporary_maximum_age') + 3),
+      ])
+      ->condition('fid', $file->id())
+      ->execute();
+    \Drupal::service('cron')->run();
+
+    // file_cron() loads
+    $this->assertFileHooksCalled(['delete']);
+    $this->assertFileDoesNotExist($file->getFileUri());
+    $this->assertNull(File::load($file->id()), 'File was removed from the database.');
+  }
+
+  /**
+   * Tries to run cron deletion on file deleted from the file-system.
+   */
+  public function testCronDeleteNonExistingTemporary(): void {
+    $file = $this->createFile();
+    // Delete the file, but leave it in the file_managed table.
+    \Drupal::service('file_system')->delete($file->getFileUri());
+    $this->assertFileDoesNotExist($file->getFileUri());
+    $this->assertInstanceOf(File::class, File::load($file->id()));
+
+    // Call file_cron() to clean up the file. Make sure the changed timestamp
+    // of the file is older than the system.file.temporary_maximum_age
+    // configuration value.
+    \Drupal::database()->update('file_managed')
+      ->fields([
+        'changed' => \Drupal::time()->getRequestTime() - ($this->config('system.file')->get('temporary_maximum_age') + 3),
+      ])
+      ->condition('fid', $file->id())
+      ->execute();
+    \Drupal::service('cron')->run();
+
+    $this->assertNull(File::load($file->id()), 'File was removed from the database.');
+  }
+
+}

core/modules/file/tests/src/Kernel/FileItemTest.php

@@ -0,0 +1,162 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel;
+
+use Drupal\Core\Field\FieldItemInterface;
+use Drupal\Core\Field\FieldItemListInterface;
+use Drupal\Core\Field\FieldStorageDefinitionInterface;
+use Drupal\entity_test\Entity\EntityTest;
+use Drupal\field\Entity\FieldConfig;
+use Drupal\Tests\field\Kernel\FieldKernelTestBase;
+use Drupal\field\Entity\FieldStorageConfig;
+use Drupal\file\Entity\File;
+use Drupal\user\Entity\Role;
+
+/**
+ * Tests using entity fields of the file field type.
+ *
+ * @group file
+ */
+class FileItemTest extends FieldKernelTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  protected static $modules = ['file'];
+
+  /**
+   * Created file entity.
+   *
+   * @var \Drupal\file\Entity\File
+   */
+  protected $file;
+
+  /**
+   * Directory where the sample files are stored.
+   *
+   * @var string
+   */
+  protected $directory;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+
+    $this->installEntitySchema('user');
+    $this->installConfig(['user']);
+    // Give anonymous users permission to access content, so they can view and
+    // download public files.
+    $anonymous_role = Role::load(Role::ANONYMOUS_ID);
+    $anonymous_role->grantPermission('access content');
+    $anonymous_role->save();
+
+    $this->installEntitySchema('file');
+    $this->installSchema('file', ['file_usage']);
+
+    FieldStorageConfig::create([
+      'field_name' => 'file_test',
+      'entity_type' => 'entity_test',
+      'type' => 'file',
+      'cardinality' => FieldStorageDefinitionInterface::CARDINALITY_UNLIMITED,
+    ])->save();
+    $this->directory = $this->getRandomGenerator()->name(8);
+    FieldConfig::create([
+      'entity_type' => 'entity_test',
+      'field_name' => 'file_test',
+      'bundle' => 'entity_test',
+      'settings' => ['file_directory' => $this->directory],
+    ])->save();
+    file_put_contents('public://example.txt', $this->randomMachineName());
+    $this->file = File::create([
+      'uri' => 'public://example.txt',
+    ]);
+    $this->file->save();
+  }
+
+  /**
+   * Tests using entity fields of the file field type.
+   */
+  public function testFileItem(): void {
+    // Check that the selection handler was automatically assigned to
+    // 'default:file'.
+    $field_definition = FieldConfig::load('entity_test.entity_test.file_test');
+    $handler_id = $field_definition->getSetting('handler');
+    $this->assertEquals('default:file', $handler_id);
+
+    // Create a test entity with the
+    $entity = EntityTest::create();
+    $entity->file_test->target_id = $this->file->id();
+    $entity->file_test->display = 1;
+    $entity->file_test->description = $description = $this->randomMachineName();
+    $entity->name->value = $this->randomMachineName();
+    $entity->save();
+
+    $entity = EntityTest::load($entity->id());
+    $this->assertInstanceOf(FieldItemListInterface::class, $entity->file_test);
+    $this->assertInstanceOf(FieldItemInterface::class, $entity->file_test[0]);
+    $this->assertEquals($this->file->id(), $entity->file_test->target_id);
+    $this->assertEquals(1, $entity->file_test->display);
+    $this->assertEquals($description, $entity->file_test->description);
+    $this->assertEquals($this->file->getFileUri(), $entity->file_test->entity->getFileUri());
+    $this->assertEquals($this->file->id(), $entity->file_test->entity->id());
+    $this->assertEquals($this->file->uuid(), $entity->file_test->entity->uuid());
+
+    // Make sure the computed files reflects updates to the file.
+    file_put_contents('public://example-2.txt', $this->randomMachineName());
+    $file2 = File::create([
+      'uri' => 'public://example-2.txt',
+    ]);
+    $file2->save();
+
+    $entity->file_test->target_id = $file2->id();
+    $this->assertEquals($entity->file_test->entity->id(), $file2->id());
+    $this->assertEquals($entity->file_test->entity->getFileUri(), $file2->getFileUri());
+
+    // Test the deletion of an entity having an entity reference field targeting
+    // a non-existing entity.
+    $file2->delete();
+    $entity->delete();
+
+    // Test the generateSampleValue() method.
+    $entity = EntityTest::create();
+    $entity->file_test->generateSampleItems();
+    $this->entityValidateAndSave($entity);
+    // Verify that the sample file was stored in the correct directory.
+    $uri = $entity->file_test->entity->getFileUri();
+
+    /** @var \Drupal\Core\StreamWrapper\StreamWrapperManagerInterface $stream_wrapper_manager */
+    $stream_wrapper_manager = \Drupal::service('stream_wrapper_manager');
+
+    $this->assertEquals($this->directory, dirname($stream_wrapper_manager::getTarget($uri)));
+
+    // Make sure the computed files reflects updates to the file.
+    file_put_contents('public://example-3.txt', $this->randomMachineName());
+    // Test unsaved file entity.
+    $file3 = File::create([
+      'uri' => 'public://example-3.txt',
+    ]);
+    $display = \Drupal::service('entity_display.repository')
+      ->getViewDisplay('entity_test', 'entity_test');
+    $display->setComponent('file_test', [
+      'label' => 'above',
+      'type' => 'file_default',
+      'weight' => 1,
+    ])->save();
+    $entity = EntityTest::create();
+    $entity->file_test = ['entity' => $file3];
+    $uri = $file3->getFileUri();
+    $output = \Drupal::entityTypeManager()
+      ->getViewBuilder('entity_test')
+      ->view($entity, 'default');
+    \Drupal::service('renderer')->renderRoot($output);
+    $this->assertTrue(!empty($entity->file_test->entity));
+    $this->assertEquals($uri, $entity->file_test->entity->getFileUri());
+  }
+
+}

core/modules/file/tests/src/Kernel/FileItemValidationTest.php

@@ -0,0 +1,137 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel;
+
+use Drupal\entity_test\Entity\EntityTest;
+use Drupal\field\Entity\FieldConfig;
+use Drupal\field\Entity\FieldStorageConfig;
+use Drupal\file\Entity\File;
+use Drupal\KernelTests\KernelTestBase;
+use Drupal\user\Entity\User;
+use org\bovigo\vfs\vfsStream;
+
+/**
+ * Tests that files referenced in file and image fields are always validated.
+ *
+ * @group file
+ */
+class FileItemValidationTest extends KernelTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = [
+    'file',
+    'image',
+    'entity_test',
+    'field',
+    'user',
+    'system',
+  ];
+
+  /**
+   * A user.
+   *
+   * @var \Drupal\user\UserInterface
+   */
+  protected $user;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+
+    $this->installEntitySchema('entity_test');
+    $this->installEntitySchema('user');
+    $this->installEntitySchema('file');
+    $this->installSchema('file', 'file_usage');
+
+    $this->user = User::create([
+      'name' => 'username',
+      'status' => 1,
+    ]);
+    $this->user->save();
+    $this->container->get('current_user')->setAccount($this->user);
+  }
+
+  /**
+   * @covers \Drupal\file\Plugin\Validation\Constraint\FileValidationConstraint
+   * @covers \Drupal\file\Plugin\Validation\Constraint\FileValidationConstraintValidator
+   * @dataProvider getFileTypes
+   */
+  public function testFileValidationConstraint($file_type): void {
+    $field_storage = FieldStorageConfig::create([
+      'field_name' => 'field_test_file',
+      'entity_type' => 'entity_test',
+      'type' => $file_type,
+    ]);
+    $field_storage->save();
+
+    $field = FieldConfig::create([
+      'field_name' => 'field_test_file',
+      'entity_type' => 'entity_test',
+      'bundle' => 'entity_test',
+      'settings' => [
+        'max_filesize' => '2k',
+        'file_extensions' => 'jpg|png',
+      ],
+    ]);
+    $field->save();
+
+    vfsStream::setup('drupal_root');
+    vfsStream::create([
+      'sites' => [
+        'default' => [
+          'files' => [
+            'test.txt' => str_repeat('a', 3000),
+          ],
+        ],
+      ],
+    ]);
+
+    // Test for max filesize.
+    $file = File::create([
+      'uri' => 'vfs://drupal_root/sites/default/files/test.txt',
+      'uid' => $this->user->id(),
+    ]);
+    $file->setPermanent();
+    $file->save();
+
+    $entity_test = EntityTest::create([
+      'uid' => $this->user->id(),
+      'field_test_file' => [
+        'target_id' => $file->id(),
+      ],
+    ]);
+    $result = $entity_test->validate();
+    $this->assertCount(2, $result);
+
+    $this->assertEquals('field_test_file.0', $result->get(0)->getPropertyPath());
+    $this->assertEquals('The file is <em class="placeholder">2.93 KB</em> exceeding the maximum file size of <em class="placeholder">2 KB</em>.', (string) $result->get(0)->getMessage());
+    $this->assertEquals('field_test_file.0', $result->get(1)->getPropertyPath());
+    $this->assertEquals('Only files with the following extensions are allowed: <em class="placeholder">jpg|png</em>.', (string) $result->get(1)->getMessage());
+
+    // Refer to a file that does not exist.
+    $entity_test = EntityTest::create([
+      'uid' => $this->user->id(),
+      'field_test_file' => [
+        'target_id' => 2,
+      ],
+    ]);
+    $result = $entity_test->validate();
+    $this->assertCount(1, $result);
+    $this->assertEquals('field_test_file.0.target_id', $result->get(0)->getPropertyPath());
+    $this->assertEquals('The referenced entity (<em class="placeholder">file</em>: <em class="placeholder">2</em>) does not exist.', (string) $result->get(0)->getMessage());
+  }
+
+  /**
+   * Provides a list of file types to test.
+   */
+  public static function getFileTypes() {
+    return [['file'], ['image']];
+  }
+
+}

core/modules/file/tests/src/Kernel/FileManagedAccessTest.php

@@ -0,0 +1,79 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel;
+
+use Drupal\Core\Session\AccountInterface;
+use Drupal\file\Entity\File;
+use Drupal\file\FileInterface;
+use Drupal\KernelTests\KernelTestBase;
+use Drupal\Tests\user\Traits\UserCreationTrait;
+use Drupal\user\Entity\User;
+
+/**
+ * Tests access to managed files.
+ *
+ * @group file
+ */
+class FileManagedAccessTest extends KernelTestBase {
+
+  use UserCreationTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = [
+    'file',
+    'system',
+    'user',
+  ];
+
+  /**
+   * Tests if public file is always accessible.
+   */
+  public function testFileAccess(): void {
+    $this->installEntitySchema('user');
+    $this->installEntitySchema('file');
+    $this->installSchema('file', ['file_usage']);
+    $this->installConfig('user');
+
+    $anonymous = User::create(['uid' => 0, 'name' => '']);
+    $anonymous->save();
+    user_role_grant_permissions(AccountInterface::ANONYMOUS_ROLE, ['access content']);
+
+    // Create an authenticated user to check file access.
+    $account = $this->createUser(['access site reports', 'access content'], NULL, FALSE, ['uid' => 2]);
+
+    // Create a new file entity in the public:// stream wrapper.
+    $file_public = File::create([
+      'uid' => 1,
+      'filename' => 'drupal.txt',
+      'uri' => 'public://drupal.txt',
+      'status' => FileInterface::STATUS_PERMANENT,
+    ]);
+    $file_public->save();
+
+    $this->assertTrue($file_public->access('view', $account));
+    $this->assertTrue($file_public->access('download', $account));
+
+    $this->assertTrue($file_public->access('view', $anonymous));
+    $this->assertTrue($file_public->access('download', $anonymous));
+
+    // Create a new file entity in the private:// stream wrapper.
+    $file_private = File::create([
+      'uid' => 1,
+      'filename' => 'drupal.txt',
+      'uri' => 'private://drupal.txt',
+      'status' => FileInterface::STATUS_PERMANENT,
+    ]);
+    $file_private->save();
+
+    $this->assertFalse($file_private->access('view', $account));
+    $this->assertFalse($file_private->access('download', $account));
+
+    $this->assertFalse($file_private->access('view', $anonymous));
+    $this->assertFalse($file_private->access('download', $anonymous));
+  }
+
+}

core/modules/file/tests/src/Kernel/FileManagedUnitTestBase.php

@@ -0,0 +1,219 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel;
+
+use Drupal\Component\Render\FormattableMarkup;
+use Drupal\file\Entity\File;
+use Drupal\file\FileInterface;
+use Drupal\KernelTests\KernelTestBase;
+use Drupal\user\Entity\User;
+
+/**
+ * Provides a base class for testing file uploads and hook invocations.
+ */
+abstract class FileManagedUnitTestBase extends KernelTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  protected static $modules = ['file_test', 'file', 'system', 'field', 'user'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    // Clear out any hook calls.
+    file_test_reset();
+
+    $this->installConfig(['system']);
+    $this->installEntitySchema('file');
+    $this->installEntitySchema('user');
+    $this->installSchema('file', ['file_usage']);
+
+    // Make sure that a user with uid 1 exists, self::createFile() relies on
+    // it.
+    $user = User::create(['uid' => 1, 'name' => $this->randomMachineName()]);
+    $user->enforceIsNew();
+    $user->save();
+    \Drupal::currentUser()->setAccount($user);
+  }
+
+  /**
+   * Asserts that the specified file hooks were called only once.
+   *
+   * @param array $expected
+   *   Array with string containing with the hook name, e.g. 'load', 'save',
+   *   'insert', etc.
+   */
+  public function assertFileHooksCalled($expected) {
+    \Drupal::state()->resetCache();
+
+    // Determine which hooks were called.
+    $actual = array_keys(array_filter(file_test_get_all_calls()));
+
+    // Determine if there were any expected that were not called.
+    $uncalled = array_diff($expected, $actual);
+    if (count($uncalled)) {
+      $this->assertTrue(FALSE, sprintf('Expected hooks %s to be called but %s was not called.', implode(', ', $expected), implode(', ', $uncalled)));
+    }
+    else {
+      $this->assertTrue(TRUE, sprintf('All the expected hooks were called: %s', empty($expected) ? '(none)' : implode(', ', $expected)));
+    }
+
+    // Determine if there were any unexpected calls.
+    $unexpected = array_diff($actual, $expected);
+    if (count($unexpected)) {
+      $this->assertTrue(FALSE, sprintf('Unexpected hooks were called: %s.', empty($unexpected) ? '(none)' : implode(', ', $unexpected)));
+    }
+    else {
+      $this->assertTrue(TRUE, 'No unexpected hooks were called.');
+    }
+  }
+
+  /**
+   * Assert that a hook_file_* hook was called a certain number of times.
+   *
+   * @param string $hook
+   *   String with the hook name, e.g. 'load', 'save', 'insert', etc.
+   * @param int $expected_count
+   *   Optional integer count.
+   * @param string $message
+   *   Optional translated string message.
+   */
+  public function assertFileHookCalled($hook, $expected_count = 1, $message = NULL) {
+    $actual_count = count(file_test_get_calls($hook));
+
+    if (!isset($message)) {
+      if ($actual_count == $expected_count) {
+        $message = new FormattableMarkup('hook_file_@name was called correctly.', ['@name' => $hook]);
+      }
+      elseif ($expected_count == 0) {
+        $message = \Drupal::translation()->formatPlural($actual_count, 'hook_file_@name was not expected to be called but was actually called once.', 'hook_file_@name was not expected to be called but was actually called @count times.', ['@name' => $hook, '@count' => $actual_count]);
+      }
+      else {
+        $message = new FormattableMarkup('hook_file_@name was expected to be called %expected times but was called %actual times.', ['@name' => $hook, '%expected' => $expected_count, '%actual' => $actual_count]);
+      }
+    }
+    $this->assertEquals($expected_count, $actual_count, (string) $message);
+  }
+
+  /**
+   * Asserts that two files have the same values (except timestamp).
+   *
+   * @param \Drupal\file\FileInterface $before
+   *   File object to compare.
+   * @param \Drupal\file\FileInterface $after
+   *   File object to compare.
+   */
+  public function assertFileUnchanged(FileInterface $before, FileInterface $after) {
+    $this->assertEquals($before->id(), $after->id(), 'File id is the same');
+    $this->assertEquals($before->getOwner()->id(), $after->getOwner()->id(), 'File owner is the same');
+    $this->assertEquals($before->getFilename(), $after->getFilename(), 'File name is the same');
+    $this->assertEquals($before->getFileUri(), $after->getFileUri(), 'File path is the same');
+    $this->assertEquals($before->getMimeType(), $after->getMimeType(), 'File MIME type is the same');
+    $this->assertEquals($before->getSize(), $after->getSize(), 'File size is the same');
+    $this->assertEquals($before->isPermanent(), $after->isPermanent(), 'File status is the same');
+  }
+
+  /**
+   * Asserts that two files are not the same by comparing the fid and filepath.
+   *
+   * @param \Drupal\file\FileInterface $file1
+   *   File object to compare.
+   * @param \Drupal\file\FileInterface $file2
+   *   File object to compare.
+   */
+  public function assertDifferentFile(FileInterface $file1, FileInterface $file2) {
+    $this->assertNotEquals($file1->id(), $file2->id(), 'Files have different ids');
+    $this->assertNotEquals($file1->getFileUri(), $file2->getFileUri(), 'Files have different paths');
+  }
+
+  /**
+   * Asserts that two files are the same by comparing the fid and filepath.
+   *
+   * @param \Drupal\file\FileInterface $file1
+   *   File object to compare.
+   * @param \Drupal\file\FileInterface $file2
+   *   File object to compare.
+   */
+  public function assertSameFile(FileInterface $file1, FileInterface $file2) {
+    $this->assertEquals($file1->id(), $file2->id(), 'Files have the same ids');
+    $this->assertEquals($file1->getFileUri(), $file2->getFileUri(), 'Files have the same path');
+  }
+
+  /**
+   * Creates and saves a file, asserting that it was saved.
+   *
+   * @param string $filepath
+   *   Optional string specifying the file path. If none is provided then a
+   *   randomly named file will be created in the site's files directory.
+   * @param string $contents
+   *   Optional contents to save into the file. If a NULL value is provided an
+   *   arbitrary string will be used.
+   * @param string $scheme
+   *   Optional string indicating the stream scheme to use. Drupal core includes
+   *   public, private, and temporary. The public wrapper is the default.
+   *
+   * @return \Drupal\file\FileInterface
+   *   File entity.
+   */
+  public function createFile($filepath = NULL, $contents = NULL, $scheme = NULL) {
+    // Don't count hook invocations caused by creating the file.
+    \Drupal::state()->set('file_test.count_hook_invocations', FALSE);
+    $file = File::create([
+      'uri' => $this->createUri($filepath, $contents, $scheme),
+      'uid' => 1,
+    ]);
+    $file->save();
+    // Write the record directly rather than using the API so we don't invoke
+    // the hooks.
+    // Verify that the file was added to the database.
+    $this->assertGreaterThan(0, $file->id());
+
+    \Drupal::state()->set('file_test.count_hook_invocations', TRUE);
+    return $file;
+  }
+
+  /**
+   * Creates a file and returns its URI.
+   *
+   * @param string $filepath
+   *   Optional string specifying the file path. If none is provided then a
+   *   randomly named file will be created in the site's files directory.
+   * @param string $contents
+   *   Optional contents to save into the file. If a NULL value is provided an
+   *   arbitrary string will be used.
+   * @param string $scheme
+   *   Optional string indicating the stream scheme to use. Drupal core includes
+   *   public, private, and temporary. The public wrapper is the default.
+   *
+   * @return string
+   *   File URI.
+   */
+  public function createUri($filepath = NULL, $contents = NULL, $scheme = NULL) {
+    if (!isset($filepath)) {
+      // Prefix with non-latin characters to ensure that all file-related
+      // tests work with international filenames.
+      // cSpell:disable-next-line
+      $filepath = 'Файл для тестирования ' . $this->randomMachineName();
+    }
+    if (!isset($scheme)) {
+      $scheme = 'public';
+    }
+    $filepath = $scheme . '://' . $filepath;
+
+    if (!isset($contents)) {
+      $contents = "file_put_contents() doesn't seem to appreciate empty strings so let's put in some data.";
+    }
+
+    file_put_contents($filepath, $contents);
+    $this->assertFileExists($filepath);
+    return $filepath;
+  }
+
+}

core/modules/file/tests/src/Kernel/FileRepositoryTest.php

@@ -0,0 +1,228 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel;
+
+use Drupal\Core\Entity\EntityStorageException;
+use Drupal\Core\Entity\EntityTypeManager;
+use Drupal\Core\File\Exception\FileExistsException;
+use Drupal\Core\File\Exception\InvalidStreamWrapperException;
+use Drupal\Core\File\FileExists;
+use Drupal\Core\StreamWrapper\StreamWrapperManagerInterface;
+use Drupal\file\Entity\File;
+use Drupal\file\FileRepository;
+
+/**
+ * Tests the FileRepository.
+ *
+ * @coversDefaultClass \Drupal\file\FileRepository
+ * @group file
+ */
+class FileRepositoryTest extends FileManagedUnitTestBase {
+
+  /**
+   * The file repository service under test.
+   *
+   * @var \Drupal\file\FileRepository
+   */
+  protected $fileRepository;
+
+  /**
+   * The file system service.
+   *
+   * @var \Drupal\Core\File\FileSystemInterface
+   */
+  protected $fileSystem;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    $this->fileRepository = $this->container->get('file.repository');
+    $this->fileSystem = $this->container->get('file_system');
+  }
+
+  /**
+   * Tests the writeData() method.
+   *
+   * @covers ::writeData
+   */
+  public function testWithFilename(): void {
+    $contents = $this->randomMachineName();
+
+    // Using filename with non-latin characters.
+    // cSpell:disable-next-line
+    $filename = 'Текстовый файл.txt';
+
+    $result = $this->fileRepository->writeData($contents, 'public://' . $filename);
+    $this->assertNotFalse($result, 'Unnamed file saved correctly.');
+
+    $stream_wrapper_manager = \Drupal::service('stream_wrapper_manager');
+    assert($stream_wrapper_manager instanceof StreamWrapperManagerInterface);
+    $this->assertEquals('public', $stream_wrapper_manager::getScheme($result->getFileUri()), "File was placed in Drupal's files directory.");
+    $this->assertEquals($filename, \Drupal::service('file_system')->basename($result->getFileUri()), 'File was named correctly.');
+    $this->assertEquals($contents, file_get_contents($result->getFileUri()), 'Contents of the file are correct.');
+    $this->assertEquals('text/plain', $result->getMimeType(), 'A MIME type was set.');
+    $this->assertTrue($result->isPermanent(), "The file's status was set to permanent.");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['insert']);
+
+    // Verify that what was returned is what's in the database.
+    $this->assertFileUnchanged($result, File::load($result->id()));
+  }
+
+  /**
+   * Tests writeData() when renaming around an existing file.
+   *
+   * @covers ::writeData
+   */
+  public function testExistingRename(): void {
+    // Setup a file to overwrite.
+    $existing = $this->createFile();
+    $contents = $this->randomMachineName();
+
+    $result = $this->fileRepository->writeData($contents, $existing->getFileUri());
+    $this->assertNotFalse($result, 'File saved successfully.');
+
+    $stream_wrapper_manager = \Drupal::service('stream_wrapper_manager');
+    assert($stream_wrapper_manager instanceof StreamWrapperManagerInterface);
+    $this->assertEquals('public', $stream_wrapper_manager::getScheme($result->getFileUri()), "File was placed in Drupal's files directory.");
+    $this->assertEquals($existing->getFilename(), $result->getFilename(), 'Filename was set to the basename of the source, rather than that of the renamed file.');
+    $this->assertEquals($contents, file_get_contents($result->getFileUri()), 'Contents of the file are correct.');
+    $this->assertEquals('application/octet-stream', $result->getMimeType(), 'A MIME type was set.');
+    $this->assertTrue($result->isPermanent(), "The file's status was set to permanent.");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['insert']);
+
+    // Ensure that the existing file wasn't overwritten.
+    $this->assertDifferentFile($existing, $result);
+    $this->assertFileUnchanged($existing, File::load($existing->id()));
+
+    // Verify that was returned is what's in the database.
+    $this->assertFileUnchanged($result, File::load($result->id()));
+  }
+
+  /**
+   * Tests writeData() when replacing an existing file.
+   *
+   * @covers ::writeData
+   */
+  public function testExistingReplace(): void {
+    // Setup a file to overwrite.
+    $existing = $this->createFile();
+    $contents = $this->randomMachineName();
+
+    $result = $this->fileRepository->writeData($contents, $existing->getFileUri(), FileExists::Replace);
+    $this->assertNotFalse($result, 'File saved successfully.');
+
+    $stream_wrapper_manager = \Drupal::service('stream_wrapper_manager');
+    assert($stream_wrapper_manager instanceof StreamWrapperManagerInterface);
+    $this->assertEquals('public', $stream_wrapper_manager::getScheme($result->getFileUri()), "File was placed in Drupal's files directory.");
+    $this->assertEquals($existing->getFilename(), $result->getFilename(), 'Filename was set to the basename of the existing file, rather than preserving the original name.');
+    $this->assertEquals($contents, file_get_contents($result->getFileUri()), 'Contents of the file are correct.');
+    $this->assertEquals('application/octet-stream', $result->getMimeType(), 'A MIME type was set.');
+    $this->assertTrue($result->isPermanent(), "The file's status was set to permanent.");
+
+    // Check that the correct hooks were called.
+    $this->assertFileHooksCalled(['load', 'update']);
+
+    // Verify that the existing file was re-used.
+    $this->assertSameFile($existing, $result);
+
+    // Verify that what was returned is what's in the database.
+    $this->assertFileUnchanged($result, File::load($result->id()));
+  }
+
+  /**
+   * Tests that writeData() fails overwriting an existing file.
+   *
+   * @covers ::writeData
+   */
+  public function testExistingError(): void {
+    $contents = $this->randomMachineName();
+    $existing = $this->createFile(NULL, $contents);
+
+    // Check the overwrite error.
+    try {
+      $this->fileRepository->writeData('asdf', $existing->getFileUri(), FileExists::Error);
+      $this->fail('expected FileExistsException');
+    }
+    // FileExistsException is a subclass of FileException.
+    catch (FileExistsException $e) {
+      // expected exception.
+      $this->assertStringContainsString("could not be copied because a file by that name already exists in the destination directory", $e->getMessage());
+    }
+    $this->assertEquals($contents, file_get_contents($existing->getFileUri()), 'Contents of existing file were unchanged.');
+
+    // Check that no hooks were called while failing.
+    $this->assertFileHooksCalled([]);
+
+    // Ensure that the existing file wasn't overwritten.
+    $this->assertFileUnchanged($existing, File::load($existing->id()));
+  }
+
+  /**
+   * Tests for an invalid stream wrapper.
+   *
+   * @covers ::writeData
+   */
+  public function testInvalidStreamWrapper(): void {
+    $this->expectException(InvalidStreamWrapperException::class);
+    $this->expectExceptionMessage('Invalid stream wrapper: foo://');
+    $this->fileRepository->writeData('asdf', 'foo://');
+  }
+
+  /**
+   * Tests for entity storage exception.
+   *
+   * @covers ::writeData
+   */
+  public function testEntityStorageException(): void {
+    /** @var \Drupal\Core\Entity\EntityTypeManager $entityTypeManager */
+    $entityTypeManager = $this->prophesize(EntityTypeManager::class);
+    $entityTypeManager->getStorage('file')
+      ->willThrow(EntityStorageException::class);
+
+    $fileRepository = new FileRepository(
+      $this->container->get('file_system'),
+      $this->container->get('stream_wrapper_manager'),
+      $entityTypeManager->reveal(),
+      $this->container->get('module_handler'),
+      $this->container->get('file.usage'),
+      $this->container->get('current_user')
+    );
+
+    $this->expectException(EntityStorageException::class);
+    $target = $this->createFile();
+    $fileRepository->writeData('asdf', $target->getFileUri(), FileExists::Replace);
+  }
+
+  /**
+   * Tests loading a file by URI.
+   *
+   * @covers ::loadByUri
+   */
+  public function testLoadByUri(): void {
+    $source = $this->createFile();
+    $result = $this->fileRepository->loadByUri($source->getFileUri());
+    $this->assertSameFile($source, $result);
+  }
+
+  /**
+   * Tests loading a file by case-sensitive URI.
+   *
+   * @covers ::loadByUri
+   */
+  public function testLoadByUriCaseSensitive(): void {
+    $source = $this->createFile('FooBar.txt');
+    $result = $this->fileRepository->loadByUri('public://FooBar.txt');
+    $this->assertSameFile($source, $result);
+    $result = $this->fileRepository->loadByUri('public://foobar.txt');
+    $this->assertNull($result);
+  }
+
+}

core/modules/file/tests/src/Kernel/FileSaveUploadTest.php

@@ -0,0 +1,72 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel;
+
+use Drupal\Core\Messenger\MessengerInterface;
+use Drupal\KernelTests\KernelTestBase;
+use Symfony\Component\HttpFoundation\File\UploadedFile;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\RequestStack;
+
+/**
+ * Tests file_save_upload().
+ *
+ * @group file
+ * @group legacy
+ */
+class FileSaveUploadTest extends KernelTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = [
+    'file',
+    'file_test',
+    'file_validator_test',
+    'user',
+  ];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    \file_put_contents('test.bbb', 'test');
+
+    parent::setUp();
+    $request = new Request();
+    $request->files->set('files', [
+      'file' => new UploadedFile(
+        path: 'test.bbb',
+        originalName: 'test.bbb',
+        mimeType: 'text/plain',
+        error: \UPLOAD_ERR_OK,
+        test: TRUE
+      ),
+    ]);
+
+    $requestStack = new RequestStack();
+    $requestStack->push($request);
+
+    $this->container->set('request_stack', $requestStack);
+  }
+
+  /**
+   * Tests file_save_upload() with empty extensions.
+   */
+  public function testFileSaveUploadEmptyExtensions(): void {
+    // Allow all extensions.
+    $validators = ['file_validate_extensions' => ''];
+    $this->expectDeprecation('\'file_validate_extensions\' is deprecated in drupal:10.2.0 and is removed from drupal:11.0.0. Use the \'FileExtension\' constraint instead. See https://www.drupal.org/node/3363700');
+    $files = file_save_upload('file', $validators);
+    $this->assertCount(1, $files);
+    $file = $files[0];
+    // @todo work out why move_uploaded_file() is failing.
+    $this->assertFalse($file);
+    $messages = \Drupal::messenger()->messagesByType(MessengerInterface::TYPE_ERROR);
+    $this->assertNotEmpty($messages);
+    $this->assertEquals('File upload error. Could not move uploaded file.', $messages[0]);
+  }
+
+}

core/modules/file/tests/src/Kernel/FileUploadHandlerTest.php

@@ -0,0 +1,111 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel;
+
+use Drupal\Core\Lock\LockAcquiringException;
+use Drupal\Core\Lock\LockBackendInterface;
+use Drupal\file\Upload\FileUploadHandler;
+use Drupal\file\Upload\UploadedFileInterface;
+use Drupal\KernelTests\KernelTestBase;
+use Symfony\Component\Mime\MimeTypeGuesserInterface;
+use Symfony\Component\Validator\ConstraintViolationList;
+
+/**
+ * Tests the file upload handler.
+ *
+ * @group file
+ */
+class FileUploadHandlerTest extends KernelTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['file', 'file_validator_test'];
+
+  /**
+   * The file upload handler under test.
+   */
+  protected FileUploadHandler $fileUploadHandler;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    $this->fileUploadHandler = $this->container->get('file.upload_handler');
+  }
+
+  /**
+   * Tests the legacy extension support.
+   *
+   * @group legacy
+   */
+  public function testLegacyExtensions(): void {
+    $filename = $this->randomMachineName() . '.txt';
+    $uploadedFile = $this->createMock(UploadedFileInterface::class);
+    $uploadedFile->expects($this->once())
+      ->method('getClientOriginalName')
+      ->willReturn($filename);
+    $uploadedFile->expects($this->once())->method('isValid')->willReturn(TRUE);
+
+    // Throw an exception in mimeTypeGuesser to return early from the method.
+    $mimeTypeGuesser = $this->createMock(MimeTypeGuesserInterface::class);
+    $mimeTypeGuesser->expects($this->once())->method('guessMimeType')
+      ->willThrowException(new \RuntimeException('Expected exception'));
+
+    $fileUploadHandler = new FileUploadHandler(
+      fileSystem: $this->container->get('file_system'),
+      entityTypeManager: $this->container->get('entity_type.manager'),
+      streamWrapperManager: $this->container->get('stream_wrapper_manager'),
+      eventDispatcher: $this->container->get('event_dispatcher'),
+      mimeTypeGuesser: $mimeTypeGuesser,
+      currentUser: $this->container->get('current_user'),
+      requestStack: $this->container->get('request_stack'),
+      fileRepository: $this->container->get('file.repository'),
+      file_validator: $this->container->get('file.validator'),
+    );
+
+    $this->expectException(\Exception::class);
+    $this->expectDeprecation('\'file_validate_extensions\' is deprecated in drupal:10.2.0 and is removed from drupal:11.0.0. Use the \'FileExtension\' constraint instead. See https://www.drupal.org/node/3363700');
+    $fileUploadHandler->handleFileUpload($uploadedFile, ['file_validate_extensions' => ['txt']]);
+
+    $subscriber = $this->container->get('file_validation_sanitization_subscriber');
+    $this->assertEquals(['txt'], $subscriber->getAllowedExtensions());
+  }
+
+  /**
+   * Test the lock acquire exception.
+   */
+  public function testLockAcquireException(): void {
+
+    $lock = $this->createMock(LockBackendInterface::class);
+    $lock->expects($this->once())->method('acquire')->willReturn(FALSE);
+
+    $fileUploadHandler = new FileUploadHandler(
+      $this->container->get('file_system'),
+      $this->container->get('entity_type.manager'),
+      $this->container->get('stream_wrapper_manager'),
+      $this->container->get('event_dispatcher'),
+      $this->container->get('file.mime_type.guesser'),
+      $this->container->get('current_user'),
+      $this->container->get('request_stack'),
+      $this->container->get('file.repository'),
+      $this->container->get('file.validator'),
+      $lock,
+      $this->container->get('validation.basic_recursive_validator_factory'),
+    );
+
+    $file_name = $this->randomMachineName();
+    $file_info = $this->createMock(UploadedFileInterface::class);
+    $file_info->expects($this->once())->method('getClientOriginalName')->willReturn($file_name);
+    $file_info->expects($this->once())->method('validate')->willReturn(new ConstraintViolationList());
+
+    $this->expectException(LockAcquiringException::class);
+    $this->expectExceptionMessage(sprintf('File "temporary://%s" is already locked for writing.', $file_name));
+
+    $fileUploadHandler->handleFileUpload(uploadedFile: $file_info, throw: FALSE);
+  }
+
+}

core/modules/file/tests/src/Kernel/FileUriItemTest.php

@@ -0,0 +1,42 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel;
+
+use Drupal\file\Entity\File;
+
+/**
+ * File URI field item test.
+ *
+ * @group file
+ *
+ * @see \Drupal\file\Plugin\Field\FieldType\FileUriItem
+ * @see \Drupal\file\FileUrl
+ */
+class FileUriItemTest extends FileManagedUnitTestBase {
+
+  /**
+   * Tests the file entity override of the URI field.
+   */
+  public function testCustomFileUriField(): void {
+    $uri = 'public://druplicon.txt';
+
+    // Create a new file entity.
+    $file = File::create([
+      'uid' => 1,
+      'filename' => 'druplicon.txt',
+      'uri' => $uri,
+      'filemime' => 'text/plain',
+    ]);
+    $file->setPermanent();
+    file_put_contents($file->getFileUri(), 'hello world');
+
+    $file->save();
+
+    $this->assertSame($uri, $file->uri->value);
+    $expected_url = base_path() . $this->siteDirectory . '/files/druplicon.txt';
+    $this->assertSame($expected_url, $file->uri->url);
+  }
+
+}

core/modules/file/tests/src/Kernel/FileUrlTest.php

@@ -0,0 +1,31 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel;
+
+use Drupal\Core\File\FileSystemInterface;
+
+/**
+ * Tests the file URL.
+ *
+ * @group file
+ */
+class FileUrlTest extends FileManagedUnitTestBase {
+
+  /**
+   * Tests public files with a different host name from settings.
+   */
+  public function testFilesUrlWithDifferentHostName(): void {
+    $test_base_url = 'http://www.example.com/cdn';
+    $this->setSetting('file_public_base_url', $test_base_url);
+    $filepath = \Drupal::service('file_system')->createFilename('test.txt', '');
+    $directory_uri = 'public://' . dirname($filepath);
+    \Drupal::service('file_system')->prepareDirectory($directory_uri, FileSystemInterface::CREATE_DIRECTORY);
+    $file = $this->createFile($filepath, NULL, 'public');
+    $url = $file->createFileUrl(FALSE);
+    $expected_url = $test_base_url . '/' . basename($filepath);
+    $this->assertSame($url, $expected_url);
+  }
+
+}

core/modules/file/tests/src/Kernel/Formatter/FileEntityFormatterTest.php

@@ -0,0 +1,194 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel\Formatter;
+
+use Drupal\Core\Entity\Entity\EntityViewDisplay;
+use Drupal\file\Entity\File;
+use Drupal\KernelTests\KernelTestBase;
+
+/**
+ * Tests the default file formatter.
+ *
+ * @group field
+ */
+class FileEntityFormatterTest extends KernelTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['file', 'user', 'file_test'];
+
+  /**
+   * The files.
+   *
+   * @var array
+   */
+  protected $files;
+
+  /**
+   * The file URL generator.
+   *
+   * @var \Drupal\Core\File\FileUrlGeneratorInterface
+   */
+  protected $fileUrlGenerator;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    $this->fileUrlGenerator = $this->container->get('file_url_generator');
+    $this->installEntitySchema('file');
+
+    $this->files = [];
+    file_put_contents('public://file.png', str_repeat('t', 10));
+    $file = File::create([
+      'uri' => 'public://file.png',
+      'filename' => 'file.png',
+    ]);
+    $file->save();
+    $this->files[] = $file;
+
+    file_put_contents('public://file.tar', str_repeat('t', 200));
+    $file = File::create([
+      'uri' => 'public://file.tar',
+      'filename' => 'file.tar',
+    ]);
+    $file->save();
+    $this->files[] = $file;
+
+    file_put_contents('public://file.tar.gz', str_repeat('t', 40000));
+    $file = File::create([
+      'uri' => 'public://file.tar.gz',
+      'filename' => 'file.tar.gz',
+    ]);
+    $file->save();
+    $this->files[] = $file;
+
+    file_put_contents('public://file', str_repeat('t', 8000000));
+    $file = File::create([
+      'uri' => 'public://file',
+      'filename' => 'file',
+    ]);
+    $file->save();
+    $this->files[] = $file;
+  }
+
+  /**
+   * Tests the file_link field formatter.
+   */
+  public function testFormatterFileLink(): void {
+    $entity_display = EntityViewDisplay::create([
+      'targetEntityType' => 'file',
+      'bundle' => 'file',
+    ]);
+    $entity_display->setComponent('filename', ['type' => 'file_link']);
+
+    $build = $entity_display->buildMultiple($this->files)[0]['filename'][0];
+    $this->assertEquals('file.png', $build['#title']);
+    $this->assertEquals($this->fileUrlGenerator->generate('public://file.png'), $build['#url']);
+  }
+
+  /**
+   * Tests the file_link field formatter.
+   */
+  public function testFormatterFileUri(): void {
+    $entity_display = EntityViewDisplay::create([
+      'targetEntityType' => 'file',
+      'bundle' => 'file',
+    ]);
+    $entity_display->setComponent('uri', ['type' => 'file_uri']);
+
+    $build = $entity_display->buildMultiple($this->files)[0]['uri'][0];
+    $this->assertEquals('public://file.png', $build['#markup']);
+
+    $entity_display->setComponent('uri', ['type' => 'file_uri', 'settings' => ['file_download_path' => TRUE]]);
+    $build = $entity_display->buildMultiple($this->files)[0]['uri'][0];
+    $this->assertEquals($this->fileUrlGenerator->generateString('public://file.png'), $build['#markup']);
+
+    $entity_display->setComponent('uri', ['type' => 'file_uri', 'settings' => ['file_download_path' => TRUE, 'link_to_file' => TRUE]]);
+    $build = $entity_display->buildMultiple($this->files)[0]['uri'][0];
+    $this->assertEquals($this->fileUrlGenerator->generateString('public://file.png'), $build['#title']);
+    $this->assertEquals($this->fileUrlGenerator->generate('public://file.png'), $build['#url']);
+  }
+
+  /**
+   * Tests the file_extension field formatter.
+   */
+  public function testFormatterFileExtension(): void {
+    $entity_display = EntityViewDisplay::create([
+      'targetEntityType' => 'file',
+      'bundle' => 'file',
+    ]);
+    $entity_display->setComponent('filename', ['type' => 'file_extension']);
+
+    $expected = ['png', 'tar', 'gz', ''];
+    foreach (array_values($this->files) as $i => $file) {
+      $build = $entity_display->build($file);
+      $this->assertEquals($expected[$i], $build['filename'][0]['#markup']);
+    }
+
+    $entity_display->setComponent('filename', ['type' => 'file_extension', 'settings' => ['extension_detect_tar' => TRUE]]);
+
+    $expected = ['png', 'tar', 'tar.gz', ''];
+    foreach (array_values($this->files) as $i => $file) {
+      $build = $entity_display->build($file);
+      $this->assertEquals($expected[$i], $build['filename'][0]['#markup']);
+    }
+  }
+
+  /**
+   * Tests the file_extension field formatter.
+   */
+  public function testFormatterFileMime(): void {
+    $entity_display = EntityViewDisplay::create([
+      'targetEntityType' => 'file',
+      'bundle' => 'file',
+    ]);
+    $entity_display->setComponent('filemime', ['type' => 'file_filemime', 'settings' => ['filemime_image' => TRUE]]);
+
+    foreach (array_values($this->files) as $i => $file) {
+      $build = $entity_display->build($file);
+      $this->assertEquals('image__file_icon', $build['filemime'][0]['#theme']);
+      $this->assertEquals(spl_object_hash($file), spl_object_hash($build['filemime'][0]['#file']));
+    }
+  }
+
+  /**
+   * Tests the file_size field formatter.
+   */
+  public function testFormatterFileSize(): void {
+    $entity_display = EntityViewDisplay::create([
+      'targetEntityType' => 'file',
+      'bundle' => 'file',
+    ]);
+    $entity_display->setComponent('filesize', ['type' => 'file_size']);
+
+    $expected = ['10 bytes', '200 bytes', '39.06 KB', '7.63 MB'];
+    foreach (array_values($this->files) as $i => $file) {
+      $build = $entity_display->build($file);
+      $this->assertEquals($expected[$i], $build['filesize'][0]['#markup']);
+    }
+  }
+
+  /**
+   * Tests the file_link field formatter using a query string.
+   */
+  public function testFormatterFileLinkWithQueryString(): void {
+    $file = File::create([
+      'uri' => 'dummy-external-readonly://file-query-string?foo=bar',
+      'filename' => 'file-query-string',
+    ]);
+    $file->save();
+    $file_link = [
+      '#theme' => 'file_link',
+      '#file' => $file,
+    ];
+
+    $output = (string) \Drupal::service('renderer')->renderRoot($file_link);
+    $this->assertStringContainsString($this->fileUrlGenerator->generate('dummy-external-readonly://file-query-string?foo=bar')->toUriString(), $output);
+  }
+
+}

core/modules/file/tests/src/Kernel/LegacyFileModuleTest.php

@@ -0,0 +1,50 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel;
+
+use Drupal\KernelTests\KernelTestBase;
+
+// cspell:ignore msword
+
+/**
+ * Tests file module deprecations.
+ *
+ * @group legacy
+ * @group file
+ */
+class LegacyFileModuleTest extends KernelTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['file'];
+
+  /**
+   * @covers ::file_progress_implementation
+   */
+  public function testFileProgressDeprecation(): void {
+    $this->expectDeprecation('file_progress_implementation() is deprecated in drupal:10.3.0 and is removed from drupal:11.0.0. Use extension_loaded(\'uploadprogress\') instead. See https://www.drupal.org/node/3397577');
+    $this->assertFalse(\file_progress_implementation());
+  }
+
+  /**
+   * @covers ::file_icon_map
+   */
+  public function testFileIconMapDeprecation(): void {
+    $this->expectDeprecation('file_icon_map() is deprecated in drupal:10.3.0 and is removed from drupal:11.0.0. Use \Drupal\file\IconMimeTypes::getGenericMimeType() instead. See https://www.drupal.org/node/3411269');
+    $mimeType = \file_icon_map('application/msword');
+    $this->assertEquals('x-office-document', $mimeType);
+  }
+
+  /**
+   * @covers ::file_icon_class
+   */
+  public function testFileIconClassDeprecation(): void {
+    $this->expectDeprecation('file_icon_class() is deprecated in drupal:10.3.0 and is removed from drupal:11.0.0. Use \Drupal\file\IconMimeTypes::getIconClass() instead. See https://www.drupal.org/node/3411269');
+    $iconClass = \file_icon_class('image/jpeg');
+    $this->assertEquals('image', $iconClass);
+  }
+
+}

core/modules/file/tests/src/Kernel/LegacyFileThemeTest.php

@@ -0,0 +1,50 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel;
+
+use Drupal\KernelTests\KernelTestBase;
+
+/**
+ * Tests legacy deprecated functions in file.module.
+ *
+ * @group file
+ * @group legacy
+ */
+class LegacyFileThemeTest extends KernelTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['file'];
+
+  /**
+   * @covers ::template_preprocess_file_upload_help
+   */
+  public function testTemplatePreprocessFileUploadHelp(): void {
+    $variables['description'] = 'foo';
+    $variables['cardinality'] = 1;
+    $variables['upload_validators'] = [
+      'file_validate_size' => [1000],
+      'file_validate_extensions' => ['txt'],
+      'file_validate_image_resolution' => ['100x100', '50x50'],
+    ];
+
+    $this->expectDeprecation('\'file_validate_size\' is deprecated in drupal:10.2.0 and is removed from drupal:11.0.0. Use the \'FileSizeLimit\' constraint instead. See https://www.drupal.org/node/3363700');
+    $this->expectDeprecation('\'file_validate_extensions\' is deprecated in drupal:10.2.0 and is removed from drupal:11.0.0. Use the \'FileExtension\' constraint instead. See https://www.drupal.org/node/3363700');
+    $this->expectDeprecation('\'file_validate_image_resolution\' is deprecated in drupal:10.2.0 and is removed from drupal:11.0.0. Use the \'FileImageDimensions\' constraint instead. See https://www.drupal.org/node/3363700');
+
+    template_preprocess_file_upload_help($variables);
+
+    $this->assertCount(5, $variables['descriptions']);
+
+    $descriptions = $variables['descriptions'];
+    $this->assertEquals('foo', $descriptions[0]);
+    $this->assertEquals('One file only.', $descriptions[1]);
+    $this->assertEquals('1000 bytes limit.', $descriptions[2]);
+    $this->assertEquals('Allowed types: txt.', $descriptions[3]);
+    $this->assertEquals('Images must be larger than 50x50 pixels. Images larger than 100x100 pixels will be resized.', $descriptions[4]);
+  }
+
+}

core/modules/file/tests/src/Kernel/LegacyValidateTest.php

@@ -0,0 +1,61 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel;
+
+/**
+ * Tests the file_validate() function.
+ *
+ * @group file
+ * @group legacy
+ */
+class LegacyValidateTest extends FileManagedUnitTestBase {
+
+  /**
+   * Tests that the validators passed into are checked.
+   */
+  public function testCallerValidation(): void {
+    $file = $this->createFile();
+
+    // Empty validators.
+    $this->expectDeprecation('file_validate() is deprecated in drupal:10.2.0 and is removed from drupal:11.0.0. Use the \'file.validator\' service instead. See https://www.drupal.org/node/3363700');
+    $this->assertEquals([], file_validate($file, []), 'Validating an empty array works successfully.');
+    $this->assertFileHooksCalled([]);
+
+    // Use the file_test.module's test validator to ensure that passing tests
+    // return correctly.
+    file_test_reset();
+    file_test_set_return('validate', []);
+    $passing = ['file_test_validator' => [[]]];
+    $this->assertEquals([], file_validate($file, $passing), 'Validating passes.');
+    $this->assertFileHooksCalled([]);
+
+    // Now test for failures in validators passed in and by hook_validate.
+    file_test_reset();
+    $failing = ['file_test_validator' => [['Failed', 'Badly']]];
+    $this->assertEquals(['Failed', 'Badly'], file_validate($file, $failing), 'Validating returns errors.');
+    $this->assertFileHooksCalled([]);
+  }
+
+  /**
+   * Tests hard-coded security check in file_validate().
+   */
+  public function testInsecureExtensions(): void {
+    $file = $this->createFile('test.php', 'Invalid PHP');
+
+    // Test that file_validate() will check for insecure extensions by default.
+    $this->expectDeprecation('file_validate() is deprecated in drupal:10.2.0 and is removed from drupal:11.0.0. Use the \'file.validator\' service instead. See https://www.drupal.org/node/3363700');
+    $errors = file_validate($file, []);
+    $this->assertEquals('For security reasons, your upload has been rejected.', $errors[0]);
+    $this->assertFileHooksCalled([]);
+    file_test_reset();
+
+    // Test that the 'allow_insecure_uploads' is respected.
+    $this->config('system.file')->set('allow_insecure_uploads', TRUE)->save();
+    $errors = file_validate($file, []);
+    $this->assertEmpty($errors);
+    $this->assertFileHooksCalled([]);
+  }
+
+}

core/modules/file/tests/src/Kernel/LegacyValidatorTest.php

@@ -0,0 +1,257 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel;
+
+use Drupal\file\Entity\File;
+
+/**
+ * Tests the functions used to validate uploaded files.
+ *
+ * @group file
+ * @group legacy
+ */
+class LegacyValidatorTest extends FileManagedUnitTestBase {
+
+  /**
+   * An image file.
+   *
+   * @var \Drupal\file\FileInterface
+   */
+  protected $image;
+
+  /**
+   * A file which is not an image.
+   *
+   * @var \Drupal\file\Entity\File
+   */
+  protected $nonImage;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+
+    $this->image = File::create();
+    $this->image->setFileUri('core/misc/druplicon.png');
+    /** @var \Drupal\Core\File\FileSystemInterface $file_system */
+    $file_system = \Drupal::service('file_system');
+    $this->image->setFilename($file_system->basename($this->image->getFileUri()));
+    $this->image->setSize(@filesize($this->image->getFileUri()));
+
+    $this->nonImage = File::create();
+    $this->nonImage->setFileUri('core/assets/vendor/jquery/jquery.min.js');
+    $this->nonImage->setFilename($file_system->basename($this->nonImage->getFileUri()));
+  }
+
+  /**
+   * Tests the file_validate_extensions() function.
+   */
+  public function testFileValidateExtensions(): void {
+    $file = File::create(['filename' => 'asdf.txt']);
+    $this->expectDeprecation('file_validate_extensions() is deprecated in drupal:10.2.0 and is removed from drupal:11.0.0. Use the \'file.validator\' service instead. See https://www.drupal.org/node/3363700');
+    $errors = file_validate_extensions($file, 'asdf txt pork');
+    $this->assertCount(0, $errors, 'Valid extension accepted.');
+
+    $file->setFilename('asdf.txt');
+    $errors = file_validate_extensions($file, 'exe png');
+    $this->assertCount(1, $errors, 'Invalid extension blocked.');
+  }
+
+  /**
+   * Tests the file_validate_extensions() function.
+   *
+   * @param array $file_properties
+   *   The properties of the file being validated.
+   * @param string[] $extensions
+   *   An array of the allowed file extensions.
+   * @param string[] $expected_errors
+   *   The expected error messages as string.
+   *
+   * @dataProvider providerTestFileValidateExtensionsOnUri
+   */
+  public function testFileValidateExtensionsOnUri(array $file_properties, array $extensions, array $expected_errors): void {
+    $file = File::create($file_properties);
+    $this->expectDeprecation('file_validate_extensions() is deprecated in drupal:10.2.0 and is removed from drupal:11.0.0. Use the \'file.validator\' service instead. See https://www.drupal.org/node/3363700');
+    $actual_errors = file_validate_extensions($file, implode(' ', $extensions));
+    $actual_errors_as_string = array_map(function ($error_message) {
+      return (string) $error_message;
+    }, $actual_errors);
+    $this->assertEquals($expected_errors, $actual_errors_as_string);
+  }
+
+  /**
+   * Data provider for ::testFileValidateExtensionsOnUri.
+   *
+   * @return array[][]
+   *   The test cases.
+   */
+  public static function providerTestFileValidateExtensionsOnUri(): array {
+    $temporary_txt_file_properties = [
+      'filename' => 'asdf.txt',
+      'uri' => 'temporary://asdf',
+      'status' => 0,
+    ];
+    $permanent_txt_file_properties = [
+      'filename' => 'asdf.txt',
+      'uri' => 'public://asdf_0.txt',
+      'status' => 1,
+    ];
+    $permanent_png_file_properties = [
+      'filename' => 'The Druplicon',
+      'uri' => 'public://druplicon.png',
+      'status' => 1,
+    ];
+    return [
+      'Temporary txt validated with "asdf", "txt", "pork"' => [
+        'File properties' => $temporary_txt_file_properties,
+        'Allowed_extensions' => ['asdf', 'txt', 'pork'],
+        'Expected errors' => [],
+      ],
+      'Temporary txt validated with "exe" and "png"' => [
+        'File properties' => $temporary_txt_file_properties,
+        'Allowed_extensions' => ['exe', 'png'],
+        'Expected errors' => [
+          'Only files with the following extensions are allowed: <em class="placeholder">exe png</em>.',
+        ],
+      ],
+      'Permanent txt validated with "asdf", "txt", "pork"' => [
+        'File properties' => $permanent_txt_file_properties,
+        'Allowed_extensions' => ['asdf', 'txt', 'pork'],
+        'Expected errors' => [],
+      ],
+      'Permanent txt validated with "exe" and "png"' => [
+        'File properties' => $permanent_txt_file_properties,
+        'Allowed_extensions' => ['exe', 'png'],
+        'Expected errors' => [
+          'Only files with the following extensions are allowed: <em class="placeholder">exe png</em>.',
+        ],
+      ],
+      'Permanent png validated with "png", "gif", "jpg", "jpeg"' => [
+        'File properties' => $permanent_png_file_properties,
+        'Allowed_extensions' => ['png', 'gif', 'jpg', 'jpeg'],
+        'Expected errors' => [],
+      ],
+      'Permanent png validated with "exe" and "txt"' => [
+        'File properties' => $permanent_png_file_properties,
+        'Allowed_extensions' => ['exe', 'txt'],
+        'Expected errors' => [
+          'Only files with the following extensions are allowed: <em class="placeholder">exe txt</em>.',
+        ],
+      ],
+    ];
+  }
+
+  /**
+   * This ensures a specific file is actually an image.
+   */
+  public function testFileValidateIsImage(): void {
+    $this->assertFileExists($this->image->getFileUri());
+    $this->expectDeprecation('file_validate_is_image() is deprecated in drupal:10.2.0 and is removed from drupal:11.0.0. Use the \'file.validator\' service instead. See https://www.drupal.org/node/3363700');
+    $errors = file_validate_is_image($this->image);
+    $this->assertCount(0, $errors, 'No error reported for our image file.');
+
+    $this->assertFileExists($this->nonImage->getFileUri());
+    $errors = file_validate_is_image($this->nonImage);
+    $this->assertCount(1, $errors, 'An error reported for our non-image file.');
+  }
+
+  /**
+   * This ensures the dimensions of a specific file is within bounds.
+   *
+   * The image will be resized if it's too large.
+   */
+  public function testFileValidateImageResolution(): void {
+    // Non-images.
+    $this->expectDeprecation('file_validate_image_resolution() is deprecated in drupal:10.2.0 and is removed from drupal:11.0.0. Use the \'file.validator\' service instead. See https://www.drupal.org/node/3363700');
+    $errors = file_validate_image_resolution($this->nonImage);
+    $this->assertCount(0, $errors, 'Should not get any errors for a non-image file.');
+    $errors = file_validate_image_resolution($this->nonImage, '50x50', '100x100');
+    $this->assertCount(0, $errors, 'Do not check the dimensions on non files.');
+
+    // Minimum size.
+    $errors = file_validate_image_resolution($this->image);
+    $this->assertCount(0, $errors, 'No errors for an image when there is no minimum or maximum dimensions.');
+    $errors = file_validate_image_resolution($this->image, 0, '200x1');
+    $this->assertCount(1, $errors, 'Got an error for an image that was not wide enough.');
+    $errors = file_validate_image_resolution($this->image, 0, '1x200');
+    $this->assertCount(1, $errors, 'Got an error for an image that was not tall enough.');
+    $errors = file_validate_image_resolution($this->image, 0, '200x200');
+    $this->assertCount(1, $errors, 'Small images report an error.');
+
+    // Maximum size.
+    if ($this->container->get('image.factory')->getToolkitId()) {
+      // Copy the image so that the original doesn't get resized.
+      copy('core/misc/druplicon.png', 'temporary://druplicon.png');
+      $this->image->setFileUri('temporary://druplicon.png');
+
+      $errors = file_validate_image_resolution($this->image, '10x5');
+      $this->assertCount(0, $errors, 'No errors should be reported when an oversized image can be scaled down.');
+
+      $image = $this->container->get('image.factory')->get($this->image->getFileUri());
+      // Verify that the image was scaled to the correct width and height.
+      $this->assertLessThanOrEqual(10, $image->getWidth());
+      $this->assertLessThanOrEqual(5, $image->getHeight());
+      // Verify that the file size has been updated after resizing.
+      $this->assertEquals($this->image->getSize(), $image->getFileSize());
+
+      // Once again, now with negative width and height to force an error.
+      copy('core/misc/druplicon.png', 'temporary://druplicon.png');
+      $this->image->setFileUri('temporary://druplicon.png');
+      $errors = file_validate_image_resolution($this->image, '-10x-5');
+      $this->assertCount(1, $errors, 'An error reported for an oversized image that can not be scaled down.');
+
+      \Drupal::service('file_system')->unlink('temporary://druplicon.png');
+    }
+    else {
+      // @todo should check that the error is returned if no toolkit is available.
+      $errors = file_validate_image_resolution($this->image, '5x10');
+      $this->assertCount(1, $errors, 'Oversize images that cannot be scaled get an error.');
+    }
+  }
+
+  /**
+   * This will ensure the filename length is valid.
+   */
+  public function testFileValidateNameLength(): void {
+    // Create a new file entity.
+    $file = File::create();
+
+    // Add a filename with an allowed length and test it.
+    $file->setFilename(str_repeat('x', 240));
+    $this->assertEquals(240, strlen($file->getFilename()));
+    $this->expectDeprecation('file_validate_name_length() is deprecated in drupal:10.2.0 and is removed from drupal:11.0.0. Use the \'file.validator\' service instead. See https://www.drupal.org/node/3363700');
+    $errors = file_validate_name_length($file);
+    $this->assertCount(0, $errors, 'No errors reported for 240 length filename.');
+
+    // Add a filename with a length too long and test it.
+    $file->setFilename(str_repeat('x', 241));
+    $errors = file_validate_name_length($file);
+    $this->assertCount(1, $errors, 'An error reported for 241 length filename.');
+
+    // Add a filename with an empty string and test it.
+    $file->setFilename('');
+    $errors = file_validate_name_length($file);
+    $this->assertCount(1, $errors, 'An error reported for 0 length filename.');
+  }
+
+  /**
+   * Tests file_validate_size().
+   */
+  public function testFileValidateSize(): void {
+    // Create a file with a size of 1000 bytes, and quotas of only 1 byte.
+    $file = File::create(['filesize' => 1000]);
+    $this->expectDeprecation('file_validate_size() is deprecated in drupal:10.2.0 and is removed from drupal:11.0.0. Use the \'file.validator\' service instead. See https://www.drupal.org/node/3363700');
+    $errors = file_validate_size($file, 0, 0);
+    $this->assertCount(0, $errors, 'No limits means no errors.');
+    $errors = file_validate_size($file, 1, 0);
+    $this->assertCount(1, $errors, 'Error for the file being over the limit.');
+    $errors = file_validate_size($file, 0, 1);
+    $this->assertCount(1, $errors, 'Error for the user being over their limit.');
+    $errors = file_validate_size($file, 1, 1);
+    $this->assertCount(2, $errors, 'Errors for both the file and their limit.');
+  }
+
+}

core/modules/file/tests/src/Kernel/LoadTest.php

@@ -0,0 +1,102 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel;
+
+use Drupal\file\Entity\File;
+use Drupal\file\FileInterface;
+
+/**
+ * Tests \Drupal\file\Entity\File::load().
+ *
+ * @group file
+ */
+class LoadTest extends FileManagedUnitTestBase {
+
+  /**
+   * Try to load a non-existent file by fid.
+   */
+  public function testLoadMissingFid(): void {
+    $this->assertNull(File::load(-1), 'Try to load an invalid fid fails.');
+    $this->assertFileHooksCalled([]);
+  }
+
+  /**
+   * Try to load a non-existent file by URI.
+   */
+  public function testLoadMissingFilepath(): void {
+    $files = \Drupal::entityTypeManager()->getStorage('file')->loadByProperties(['uri' => 'foobar://misc/druplicon.png']);
+    $this->assertFalse(reset($files), "Try to load a file that doesn't exist in the database fails.");
+    $this->assertFileHooksCalled([]);
+  }
+
+  /**
+   * Try to load a non-existent file by status.
+   */
+  public function testLoadInvalidStatus(): void {
+    $files = \Drupal::entityTypeManager()->getStorage('file')->loadByProperties(['status' => -99]);
+    $this->assertFalse(reset($files), 'Trying to load a file with an invalid status fails.');
+    $this->assertFileHooksCalled([]);
+  }
+
+  /**
+   * Load a single file and ensure that the correct values are returned.
+   */
+  public function testSingleValues(): void {
+    // Create a new file entity from scratch so we know the values.
+    $file = $this->createFile('druplicon.txt', NULL, 'public');
+    $by_fid_file = File::load($file->id());
+    $this->assertFileHookCalled('load');
+    $this->assertIsObject($by_fid_file);
+    $this->assertEquals($file->id(), $by_fid_file->id(), 'Loading by fid got the same fid.');
+    $this->assertEquals($file->getFileUri(), $by_fid_file->getFileUri(), 'Loading by fid got the correct filepath.');
+    $this->assertEquals($file->getFilename(), $by_fid_file->getFilename(), 'Loading by fid got the correct filename.');
+    $this->assertEquals($file->getMimeType(), $by_fid_file->getMimeType(), 'Loading by fid got the correct MIME type.');
+    $this->assertEquals($file->isPermanent(), $by_fid_file->isPermanent(), 'Loading by fid got the correct status.');
+    $this->assertTrue($by_fid_file->file_test['loaded'], 'file_test_file_load() was able to modify the file during load.');
+  }
+
+  /**
+   * This will test loading file data from the database.
+   */
+  public function testMultiple(): void {
+    // Create a new file entity.
+    $file = $this->createFile('druplicon.txt', NULL, 'public');
+
+    // Load by path.
+    file_test_reset();
+    $by_path_files = \Drupal::entityTypeManager()->getStorage('file')->loadByProperties(['uri' => $file->getFileUri()]);
+    $this->assertFileHookCalled('load');
+    $this->assertCount(1, $by_path_files, '\Drupal::entityTypeManager()->getStorage(\'file\')->loadByProperties() returned an array of the correct size.');
+    $by_path_file = reset($by_path_files);
+    $this->assertTrue($by_path_file->file_test['loaded'], 'file_test_file_load() was able to modify the file during load.');
+    $this->assertEquals($file->id(), $by_path_file->id(), 'Loading by filepath got the correct fid.');
+
+    // Load by fid.
+    file_test_reset();
+    $by_fid_files = File::loadMultiple([$file->id()]);
+    $this->assertFileHooksCalled([]);
+    $this->assertCount(1, $by_fid_files, '\Drupal\file\Entity\File::loadMultiple() returned an array of the correct size.');
+    $by_fid_file = reset($by_fid_files);
+    $this->assertTrue($by_fid_file->file_test['loaded'], 'file_test_file_load() was able to modify the file during load.');
+    $this->assertEquals($file->getFileUri(), $by_fid_file->getFileUri(), 'Loading by fid got the correct filepath.');
+  }
+
+  /**
+   * Loads a single file and ensure that the correct values are returned.
+   */
+  public function testUuidValues(): void {
+    // Create a new file entity from scratch so we know the values.
+    $file = $this->createFile('druplicon.txt', NULL, 'public');
+    $file->save();
+    file_test_reset();
+
+    $by_uuid_file = \Drupal::service('entity.repository')->loadEntityByUuid('file', $file->uuid());
+    $this->assertFileHookCalled('load');
+    $this->assertInstanceOf(FileInterface::class, $by_uuid_file);
+    $this->assertEquals($file->id(), $by_uuid_file->id(), 'Loading by UUID got the same fid.');
+    $this->assertTrue($by_uuid_file->file_test['loaded'], 'file_test_file_load() was able to modify the file during load.');
+  }
+
+}

core/modules/file/tests/src/Kernel/ManagedFileTest.php

@@ -0,0 +1,59 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel;
+
+use Drupal\Core\Form\FormInterface;
+use Drupal\Core\Form\FormState;
+use Drupal\Core\Form\FormStateInterface;
+
+/**
+ * Managed file element test.
+ *
+ * @group file
+ *
+ * @see \Drupal\file\Element\ManagedFile
+ */
+class ManagedFileTest extends FileManagedUnitTestBase implements FormInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'form_test_managed_file';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+    $form['managed_file'] = [
+      '#type' => 'managed_file',
+    ];
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validateForm(array &$form, FormStateInterface $form_state) {}
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {}
+
+  /**
+   * Tests that managed file elements can be programmatically submitted.
+   */
+  public function testManagedFileElement(): void {
+    $form_state = new FormState();
+    $values['managed_file'] = NULL;
+    $form_state->setValues($values);
+    $this->container->get('form_builder')->submitForm($this, $form_state);
+    // Should submit without any errors.
+    $this->assertEquals(0, count($form_state->getErrors()));
+  }
+
+}

core/modules/file/tests/src/Kernel/Migrate/MigrateFileStubTest.php

@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel\Migrate;
+
+use Drupal\Tests\migrate_drupal\Kernel\MigrateDrupalTestBase;
+use Drupal\migrate_drupal\Tests\StubTestTrait;
+
+/**
+ * Test stub creation for file entities.
+ *
+ * @group file
+ */
+class MigrateFileStubTest extends MigrateDrupalTestBase {
+
+  use StubTestTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['file'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    $this->installEntitySchema('file');
+  }
+
+  /**
+   * Tests creation of file stubs.
+   */
+  public function testStub(): void {
+    $this->performStubTest('file');
+  }
+
+}

core/modules/file/tests/src/Kernel/Migrate/d6/FileMigrationTestTrait.php

@@ -0,0 +1,40 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel\Migrate\d6;
+
+use Drupal\migrate\Plugin\MigrationInterface;
+
+/**
+ * Helper for setting up a file migration test.
+ */
+trait FileMigrationTestTrait {
+
+  /**
+   * Setup and execute d6_file migration.
+   */
+  protected function setUpMigratedFiles() {
+    $this->installEntitySchema('file');
+    $this->installConfig(['file']);
+
+    $this->executeMigration('d6_file');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function prepareMigration(MigrationInterface $migration) {
+    // File migrations need a source_base_path.
+    // @see MigrateUpgradeRunBatch::run
+    $destination = $migration->getDestinationConfiguration();
+    if ($destination['plugin'] === 'entity:file') {
+      // Make sure we have a single trailing slash.
+      $source = $migration->getSourceConfiguration();
+      $source['site_path'] = 'core/tests/fixtures';
+      $source['constants']['source_base_path'] = $this->root . '/';
+      $migration->set('source', $source);
+    }
+  }
+
+}

core/modules/file/tests/src/Kernel/Migrate/d6/MigrateFileConfigsTest.php

@@ -0,0 +1,38 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel\Migrate\d6;
+
+use Drupal\Tests\SchemaCheckTestTrait;
+use Drupal\Tests\migrate_drupal\Kernel\d6\MigrateDrupal6TestBase;
+
+/**
+ * Upgrade variables to file.settings.yml.
+ *
+ * @group migrate_drupal_6
+ */
+class MigrateFileConfigsTest extends MigrateDrupal6TestBase {
+
+  use SchemaCheckTestTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    $this->executeMigration('file_settings');
+  }
+
+  /**
+   * Tests migration of file variables to file.settings.yml.
+   */
+  public function testFileSettings(): void {
+    $config = $this->config('file.settings');
+    $this->assertSame('textfield', $config->get('description.type'));
+    $this->assertSame(128, $config->get('description.length'));
+    $this->assertSame('sites/default/files/icons', $config->get('icon.directory'));
+    $this->assertConfigSchema(\Drupal::service('config.typed'), 'file.settings', $config->get());
+  }
+
+}

core/modules/file/tests/src/Kernel/Migrate/d6/MigrateFileTest.php

@@ -0,0 +1,175 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel\Migrate\d6;
+
+use Drupal\file\Entity\File;
+use Drupal\file\FileInterface;
+use Drupal\KernelTests\KernelTestBase;
+use Drupal\Core\Database\Database;
+use Drupal\Tests\migrate\Kernel\MigrateDumpAlterInterface;
+use Drupal\Tests\migrate_drupal\Kernel\d6\MigrateDrupal6TestBase;
+
+/**
+ * Test file migration.
+ *
+ * @group migrate_drupal_6
+ */
+class MigrateFileTest extends MigrateDrupal6TestBase implements MigrateDumpAlterInterface {
+
+  use FileMigrationTestTrait;
+
+  /**
+   * The filename of a file used to test temporary file migration.
+   *
+   * @var string
+   */
+  protected static $tempFilename;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+
+    // Remove the file_directory_path to test site_path setting.
+    // @see \Drupal\Tests\file\Kernel\Migrate\d6\FileMigrationTestTrait::prepareMigration()
+    Database::getConnection('default', 'migrate')
+      ->delete('variable')
+      ->condition('name', 'file_directory_path')
+      ->execute();
+
+    $this->setUpMigratedFiles();
+  }
+
+  /**
+   * Asserts a file entity.
+   *
+   * @param int $fid
+   *   The file ID.
+   * @param string $name
+   *   The expected file name.
+   * @param int $size
+   *   The expected file size.
+   * @param string $uri
+   *   The expected file URI.
+   * @param string $type
+   *   The expected MIME type.
+   * @param int $uid
+   *   The expected file owner ID.
+   *
+   * @internal
+   */
+  protected function assertEntity(int $fid, string $name, int $size, string $uri, string $type, int $uid): void {
+    /** @var \Drupal\file\FileInterface $file */
+    $file = File::load($fid);
+    $this->assertInstanceOf(FileInterface::class, $file);
+    $this->assertSame($name, $file->getFilename());
+    $this->assertSame($size, (int) $file->getSize());
+    $this->assertSame($uri, $file->getFileUri());
+    $this->assertSame($type, $file->getMimeType());
+    $this->assertSame($uid, (int) $file->getOwnerId());
+  }
+
+  /**
+   * Tests the Drupal 6 files to Drupal 8 migration.
+   */
+  public function testFiles(): void {
+    $this->assertEntity(1, 'Image1.png', 39325, 'public://image-1.png', 'image/png', 1);
+    $this->assertEntity(2, 'Image2.jpg', 1831, 'public://image-2.jpg', 'image/jpeg', 1);
+    $this->assertEntity(3, 'image-3.jpg', 1831, 'public://image-3.jpg', 'image/jpeg', 1);
+    $this->assertEntity(4, 'html-1.txt', 19, 'public://html-1.txt', 'text/plain', 1);
+    // Ensure temporary file was not migrated.
+    $this->assertNull(File::load(6));
+
+    $map_table = $this->getMigration('d6_file')->getIdMap()->mapTableName();
+    $map = \Drupal::database()
+      ->select($map_table, 'm')
+      ->fields('m', ['sourceid1', 'destid1'])
+      ->execute()
+      ->fetchAllKeyed();
+    $map_expected = [
+      // The 4 files from the fixture.
+      1 => '1',
+      2 => '2',
+      // The file updated in migrateDumpAlter().
+      3 => '3',
+      5 => '4',
+      // The file created in migrateDumpAlter().
+      7 => '4',
+    ];
+    $this->assertEquals($map_expected, $map);
+
+    // Test that we can re-import and also test with file_directory_path set.
+    \Drupal::database()
+      ->truncate($map_table)
+      ->execute();
+
+    // Set the file_directory_path.
+    Database::getConnection('default', 'migrate')
+      ->insert('variable')
+      ->fields(['name', 'value'])
+      ->values(['name' => 'file_directory_path', 'value' => serialize('files/test')])
+      ->execute();
+
+    $this->executeMigration('d6_file');
+
+    // File 2, when migrated for the second time, is treated as a different file
+    // (due to having a different uri this time) and is given fid 6.
+    $file = File::load(6);
+    $this->assertSame('public://core/tests/fixtures/files/image-2.jpg', $file->getFileUri());
+
+    $map_table = $this->getMigration('d6_file')->getIdMap()->mapTableName();
+    $map = \Drupal::database()
+      ->select($map_table, 'm')
+      ->fields('m', ['sourceid1', 'destid1'])
+      ->execute()
+      ->fetchAllKeyed();
+    $map_expected = [
+      // The 4 files from the fixture.
+      1 => '5',
+      2 => '6',
+      // The file updated in migrateDumpAlter().
+      3 => '7',
+      5 => '8',
+      // The files created in migrateDumpAlter().
+      7 => '8',
+      8 => '8',
+    ];
+    $this->assertEquals($map_expected, $map);
+
+    // File 6, created in static::migrateDumpAlter(), shares a path with
+    // file 4, which means it should be skipped entirely. If it was migrated
+    // then it would have an fid of 9.
+    $this->assertNull(File::load(9));
+
+    $this->assertCount(8, File::loadMultiple());
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function migrateDumpAlter(KernelTestBase $test) {
+    $db = Database::getConnection('default', 'migrate');
+
+    $db->update('files')
+      ->condition('fid', 3)
+      ->fields([
+        'filename' => 'image-3.jpg',
+        'filepath' => 'core/tests/fixtures/files/image-3.jpg',
+      ])
+      ->execute();
+
+    $file = (array) $db->select('files')
+      ->fields('files')
+      ->condition('fid', 5)
+      ->execute()
+      ->fetchObject();
+    unset($file['fid']);
+    $db->insert('files')->fields($file)->execute();
+
+    return static::$tempFilename;
+  }
+
+}

core/modules/file/tests/src/Kernel/Migrate/d6/MigrateUploadEntityDisplayTest.php

@@ -0,0 +1,71 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel\Migrate\d6;
+
+use Drupal\Core\Entity\Entity\EntityViewDisplay;
+use Drupal\Tests\migrate_drupal\Kernel\d6\MigrateDrupal6TestBase;
+
+/**
+ * Upload entity display.
+ *
+ * @group migrate_drupal_6
+ */
+class MigrateUploadEntityDisplayTest extends MigrateDrupal6TestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['menu_ui'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    $this->migrateFields();
+  }
+
+  /**
+   * Tests Drupal 6 upload settings to Drupal 8 entity display migration.
+   */
+  public function testUploadEntityDisplay(): void {
+    $this->executeMigration('d6_upload_entity_display');
+
+    $display = EntityViewDisplay::load('node.page.default');
+    $component = $display->getComponent('upload');
+    $this->assertSame('file_default', $component['type']);
+
+    $display = EntityViewDisplay::load('node.story.default');
+    $component = $display->getComponent('upload');
+    $this->assertSame('file_default', $component['type']);
+
+    // Assure this doesn't exist.
+    $display = EntityViewDisplay::load('node.article.default');
+    $component = $display->getComponent('upload');
+    $this->assertNull($component);
+
+    $this->assertSame([['node', 'page', 'default', 'upload']], $this->getMigration('d6_upload_entity_display')->getIdMap()->lookupDestinationIds(['page']));
+  }
+
+  /**
+   * Tests that entity displays are ignored appropriately.
+   *
+   * Entity displays should be ignored when they belong to node types which
+   * were not migrated.
+   */
+  public function testSkipNonExistentNodeType(): void {
+    // The "story" node type is migrated by d6_node_type but we need to pretend
+    // that it didn't occur, so record that in the map table.
+    $this->mockFailure('d6_node_type', ['type' => 'story']);
+
+    // d6_upload_entity_display should skip over the "story" node type config
+    // because, according to the map table, it didn't occur.
+    $migration = $this->getMigration('d6_upload_entity_display');
+
+    $this->executeMigration($migration);
+    $this->assertNull($migration->getIdMap()->lookupDestinationIds(['node_type' => 'story'])[0][0]);
+  }
+
+}

core/modules/file/tests/src/Kernel/Migrate/d6/MigrateUploadEntityFormDisplayTest.php

@@ -0,0 +1,71 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel\Migrate\d6;
+
+use Drupal\Core\Entity\Entity\EntityFormDisplay;
+use Drupal\Tests\migrate_drupal\Kernel\d6\MigrateDrupal6TestBase;
+
+/**
+ * Upload form entity display.
+ *
+ * @group migrate_drupal_6
+ */
+class MigrateUploadEntityFormDisplayTest extends MigrateDrupal6TestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['menu_ui'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    $this->migrateFields();
+  }
+
+  /**
+   * Tests Drupal 6 upload settings to Drupal 8 entity form display migration.
+   */
+  public function testUploadEntityFormDisplay(): void {
+    $this->executeMigration('d6_upload_entity_form_display');
+
+    $display = EntityFormDisplay::load('node.page.default');
+    $component = $display->getComponent('upload');
+    $this->assertSame('file_generic', $component['type']);
+
+    $display = EntityFormDisplay::load('node.story.default');
+    $component = $display->getComponent('upload');
+    $this->assertSame('file_generic', $component['type']);
+
+    // Assure this doesn't exist.
+    $display = EntityFormDisplay::load('node.article.default');
+    $component = $display->getComponent('upload');
+    $this->assertNull($component);
+
+    $this->assertSame([['node', 'page', 'default', 'upload']], $this->getMigration('d6_upload_entity_form_display')->getIdMap()->lookupDestinationIds(['page']));
+  }
+
+  /**
+   * Tests that entity displays are ignored appropriately.
+   *
+   * Entity displays should be ignored when they belong to node types which
+   * were not migrated.
+   */
+  public function testSkipNonExistentNodeType(): void {
+    // The "story" node type is migrated by d6_node_type but we need to pretend
+    // that it didn't occur, so record that in the map table.
+    $this->mockFailure('d6_node_type', ['type' => 'story']);
+
+    // d6_upload_entity_form_display should skip over the "story" node type
+    // config because according to the map table, it didn't occur.
+    $migration = $this->getMigration('d6_upload_entity_form_display');
+
+    $this->executeMigration($migration);
+    $this->assertNull($migration->getIdMap()->lookupDestinationIds(['node_type' => 'story'])[0][0]);
+  }
+
+}

core/modules/file/tests/src/Kernel/Migrate/d6/MigrateUploadFieldTest.php

@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel\Migrate\d6;
+
+use Drupal\field\Entity\FieldStorageConfig;
+use Drupal\Tests\migrate_drupal\Kernel\d6\MigrateDrupal6TestBase;
+
+/**
+ * Uploads migration.
+ *
+ * @group migrate_drupal_6
+ */
+class MigrateUploadFieldTest extends MigrateDrupal6TestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['menu_ui'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    $this->migrateFields();
+  }
+
+  /**
+   * Tests the Drupal 6 upload settings to Drupal 8 field migration.
+   */
+  public function testUpload(): void {
+    $field_storage = FieldStorageConfig::load('node.upload');
+    $this->assertSame('node.upload', $field_storage->id());
+    $this->assertSame([['node', 'upload']], $this->getMigration('d6_upload_field')->getIdMap()->lookupDestinationIds(['']));
+  }
+
+}

core/modules/file/tests/src/Kernel/Migrate/d6/MigrateUploadInstanceTest.php

@@ -0,0 +1,51 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel\Migrate\d6;
+
+use Drupal\field\Entity\FieldConfig;
+use Drupal\Tests\migrate_drupal\Kernel\d6\MigrateDrupal6TestBase;
+
+/**
+ * Upload field instance migration.
+ *
+ * @group migrate_drupal_6
+ */
+class MigrateUploadInstanceTest extends MigrateDrupal6TestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['menu_ui'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    $this->migrateFields();
+  }
+
+  /**
+   * Tests the Drupal 6 upload settings to Drupal 8 field instance migration.
+   */
+  public function testUploadFieldInstance(): void {
+    $field = FieldConfig::load('node.page.upload');
+    $settings = $field->getSettings();
+    $this->assertSame('node.page.upload', $field->id());
+    $this->assertSame('jpg jpeg gif png txt doc xls pdf ppt pps odt ods odp', $settings['file_extensions']);
+    $this->assertSame('1MB', $settings['max_filesize']);
+    $this->assertTrue($settings['description_field']);
+
+    $field = FieldConfig::load('node.story.upload');
+    $this->assertSame('node.story.upload', $field->id());
+
+    // Shouldn't exist.
+    $field = FieldConfig::load('node.article.upload');
+    $this->assertNull($field);
+
+    $this->assertSame([['node', 'page', 'upload']], $this->getMigration('d6_upload_field_instance')->getIdMap()->lookupDestinationIds(['page']));
+  }
+
+}

core/modules/file/tests/src/Kernel/Migrate/d6/MigrateUploadTest.php

@@ -0,0 +1,102 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel\Migrate\d6;
+
+use Drupal\file\Entity\File;
+use Drupal\Tests\migrate_drupal\Kernel\d6\MigrateDrupal6TestBase;
+use Drupal\node\Entity\Node;
+
+/**
+ * Migrate association data between nodes and files.
+ *
+ * @group migrate_drupal_6
+ */
+class MigrateUploadTest extends MigrateDrupal6TestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = [
+    'language',
+    'content_translation',
+    'menu_ui',
+  ];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+
+    $this->installEntitySchema('file');
+    $this->installEntitySchema('node');
+    $this->installSchema('file', ['file_usage']);
+    $this->installSchema('node', ['node_access']);
+
+    $id_mappings = ['d6_file' => []];
+    // Create new file entities.
+    for ($i = 1; $i <= 3; $i++) {
+      $file = File::create([
+        'fid' => $i,
+        'uid' => 1,
+        'filename' => 'druplicon.txt',
+        'uri' => "public://druplicon-$i.txt",
+        'filemime' => 'text/plain',
+        'created' => 1,
+        'changed' => 1,
+      ]);
+      $file->setPermanent();
+      $file->enforceIsNew();
+      file_put_contents($file->getFileUri(), 'hello world');
+
+      // Save it, inserting a new record.
+      $file->save();
+      $id_mappings['d6_file'][] = [[$i], [$i]];
+    }
+    $this->prepareMigrations($id_mappings);
+
+    $this->migrateContent(['translations']);
+    // Since we are only testing a subset of the file migration, do not check
+    // that the full file migration has been run.
+    $migration = $this->getMigration('d6_upload');
+    $migration->set('requirements', []);
+    $this->executeMigration($migration);
+  }
+
+  /**
+   * Tests upload migration from Drupal 6 to Drupal 8.
+   */
+  public function testUpload(): void {
+    $this->container->get('entity_type.manager')
+      ->getStorage('node')
+      ->resetCache([1, 2, 12]);
+
+    $nodes = Node::loadMultiple([1, 2, 12]);
+    $node = $nodes[1];
+    $this->assertEquals('en', $node->langcode->value);
+    $this->assertCount(1, $node->upload);
+    $this->assertSame('1', $node->upload[0]->target_id);
+    $this->assertSame('file 1-1-1', $node->upload[0]->description);
+    $this->assertFalse($node->upload[0]->isDisplayed());
+
+    $node = $nodes[2];
+    $this->assertEquals('en', $node->langcode->value);
+    $this->assertCount(2, $node->upload);
+    $this->assertSame('3', $node->upload[0]->target_id);
+    $this->assertSame('file 2-3-3', $node->upload[0]->description);
+    $this->assertFalse($node->upload[0]->isDisplayed());
+    $this->assertSame('2', $node->upload[1]->target_id);
+    $this->assertTrue($node->upload[1]->isDisplayed());
+    $this->assertSame('file 2-3-2', $node->upload[1]->description);
+
+    $node = $nodes[12];
+    $this->assertEquals('zu', $node->langcode->value);
+    $this->assertCount(1, $node->upload);
+    $this->assertEquals('3', $node->upload[0]->target_id);
+    $this->assertEquals('file 12-15-3', $node->upload[0]->description);
+    $this->assertEquals(FALSE, $node->upload[0]->isDisplayed());
+  }
+
+}

core/modules/file/tests/src/Kernel/Migrate/d7/FileMigrationSetupTrait.php

@@ -0,0 +1,83 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel\Migrate\d7;
+
+use Drupal\file\Entity\File;
+use Drupal\file\FileInterface;
+
+/**
+ * A trait to setup the file migration.
+ */
+trait FileMigrationSetupTrait {
+
+  /**
+   * Returns information about the file to be migrated.
+   *
+   * @return array
+   *   Array with keys 'path', 'size', 'base_path', and 'plugin_id'.
+   */
+  abstract protected function getFileMigrationInfo();
+
+  /**
+   * Prepare the file migration for running.
+   */
+  protected function fileMigrationSetup() {
+    $this->installEntitySchema('file');
+    $this->installSchema('file', ['file_usage']);
+
+    $info = $this->getFileMigrationInfo();
+    $fs = $this->container->get('file_system');
+    // Ensure that the files directory exists.
+    $fs->mkdir(dirname($info['path']), NULL, TRUE);
+    // Put test file in the source directory.
+    file_put_contents($info['path'], str_repeat('*', $info['size']));
+
+    /** @var \Drupal\migrate\Plugin\Migration $migration */
+    $migration = $this->getMigration($info['plugin_id']);
+    // Set the source plugin's source_base_path configuration value, which
+    // would normally be set by the user running the migration.
+    $source = $migration->getSourceConfiguration();
+    $source['constants']['source_base_path'] = $fs->realpath($info['base_path']);
+    $migration->set('source', $source);
+    $this->executeMigration($migration);
+  }
+
+  /**
+   * Tests a single file entity.
+   *
+   * @param int $id
+   *   The file ID.
+   * @param string $name
+   *   The expected file name.
+   * @param string $uri
+   *   The expected URI.
+   * @param string $mime
+   *   The expected MIME type.
+   * @param string $size
+   *   The expected file size.
+   * @param string $created
+   *   The expected creation time.
+   * @param string $changed
+   *   The expected modification time.
+   * @param string $uid
+   *   The expected owner ID.
+   */
+  protected function assertEntity($id, $name, $uri, $mime, $size, $created, $changed, $uid) {
+    /** @var \Drupal\file\FileInterface $file */
+    $file = File::load($id);
+    $this->assertInstanceOf(FileInterface::class, $file);
+    $this->assertSame($name, $file->getFilename());
+    $this->assertSame($uri, $file->getFileUri());
+    $this->assertFileExists($uri);
+    $this->assertSame($mime, $file->getMimeType());
+    $this->assertSame($size, $file->getSize());
+    // isPermanent(), isTemporary(), etc. are determined by the status column.
+    $this->assertTrue($file->isPermanent());
+    $this->assertSame($created, $file->getCreatedTime());
+    $this->assertSame($changed, $file->getChangedTime());
+    $this->assertSame($uid, $file->getOwnerId());
+  }
+
+}

core/modules/file/tests/src/Kernel/Migrate/d7/MigrateFileConfigsTest.php

@@ -0,0 +1,38 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel\Migrate\d7;
+
+use Drupal\Tests\SchemaCheckTestTrait;
+use Drupal\Tests\migrate_drupal\Kernel\d7\MigrateDrupal7TestBase;
+
+/**
+ * Upgrade variables to file.settings.yml.
+ *
+ * @group migrate_drupal_7
+ */
+class MigrateFileConfigsTest extends MigrateDrupal7TestBase {
+
+  use SchemaCheckTestTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    $this->executeMigration('file_settings');
+  }
+
+  /**
+   * Tests migration of file variables to file.settings.yml.
+   */
+  public function testFileSettings(): void {
+    $config = $this->config('file.settings');
+    $this->assertSame('textfield', $config->get('description.type'));
+    $this->assertSame(256, $config->get('description.length'));
+    $this->assertSame('sites/default/files/icons', $config->get('icon.directory'));
+    $this->assertConfigSchema(\Drupal::service('config.typed'), 'file.settings', $config->get());
+  }
+
+}

core/modules/file/tests/src/Kernel/Migrate/d7/MigrateFileGetIdsTest.php

@@ -0,0 +1,28 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\file\Kernel\Migrate\d7;
+
+/**
+ * Tests the migration of used files.
+ *
+ * @group file
+ */
+class MigrateFileGetIdsTest extends MigrateFileTest {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['file', 'file_test_get_ids'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getFileMigrationInfo() {
+    $migration_info = parent::getFileMigrationInfo();
+    $migration_info['plugin_id'] = 'd7_file_used';
+    return $migration_info;
+  }
+
+}