first commit

core/modules/system/tests/css/system.module.css

@@ -0,0 +1,5 @@
+/**
+ * This file is for testing CSS file override in
+ * CascadingStylesheetsTestCase::testRenderOverride().
+ * No contents are necessary.
+ */

core/modules/system/tests/fixtures/HtaccessTest/composer.json

@@ -0,0 +1 @@
+{}

core/modules/system/tests/fixtures/HtaccessTest/composer.lock

@@ -0,0 +1 @@
+{}

core/modules/system/tests/fixtures/HtaccessTest/package.json

@@ -0,0 +1 @@
+{}

core/modules/system/tests/fixtures/linkset/linkset-menu-main-multilingual-aa.json

@@ -0,0 +1,33 @@
+{
+  "linkset": [
+    {
+      "anchor": "/aa/system/menu/main/linkset",
+      "item": [
+        {
+          "href": "/aa",
+          "title": "Home",
+          "hierarchy": ["0"],
+          "machine-name": ["main"]
+        },
+        {
+          "href": "/aa/node/1",
+          "title": "aa|A multi-lingual-node",
+          "hierarchy": ["1"],
+          "machine-name": ["main"]
+        },
+        {
+          "href": "/aa/node/2",
+          "title": "aa|Second multi-lingual-node",
+          "hierarchy": ["2"],
+          "machine-name": ["main"]
+        },
+        {
+          "href": "/aa/node/3",
+          "title": "aa|Third multi-lingual-node",
+          "hierarchy": ["3"],
+          "machine-name": ["main"]
+        }
+      ]
+    }
+  ]
+}

core/modules/system/tests/fixtures/linkset/linkset-menu-main-multilingual-bb.json

@@ -0,0 +1,33 @@
+{
+  "linkset": [
+    {
+      "anchor": "/bb/system/menu/main/linkset",
+      "item": [
+        {
+          "href": "/bb",
+          "title": "Home",
+          "hierarchy": ["0"],
+          "machine-name": ["main"]
+        },
+        {
+          "href": "/bb/node/1",
+          "title": "bb|A multi-lingual-node",
+          "hierarchy": ["1"],
+          "machine-name": ["main"]
+        },
+        {
+          "href": "/bb/node/2",
+          "title": "bb|Second multi-lingual-node",
+          "hierarchy": ["2"],
+          "machine-name": ["main"]
+        },
+        {
+          "href": "/bb/node/3",
+          "title": "bb|Third multi-lingual-node",
+          "hierarchy": ["3"],
+          "machine-name": ["main"]
+        }
+      ]
+    }
+  ]
+}

core/modules/system/tests/fixtures/linkset/linkset-menu-main-multilingual-cc.json

@@ -0,0 +1,33 @@
+{
+  "linkset": [
+    {
+      "anchor": "/cc/system/menu/main/linkset",
+      "item": [
+        {
+          "href": "/cc",
+          "title": "Home",
+          "hierarchy": ["0"],
+          "machine-name": ["main"]
+        },
+        {
+          "href": "/cc/node/1",
+          "title": "cc|A multi-lingual-node",
+          "hierarchy": ["1"],
+          "machine-name": ["main"]
+        },
+        {
+          "href": "/cc/node/2",
+          "title": "aa|Second multi-lingual-node",
+          "hierarchy": ["2"],
+          "machine-name": ["main"]
+        },
+        {
+          "href": "/cc/node/3",
+          "title": "aa|Third multi-lingual-node",
+          "hierarchy": ["3"],
+          "machine-name": ["main"]
+        }
+      ]
+    }
+  ]
+}

core/modules/system/tests/fixtures/linkset/linkset-menu-main-multilingual-dd.json

@@ -0,0 +1,33 @@
+{
+  "linkset": [
+    {
+      "anchor": "/dd/system/menu/main/linkset",
+      "item": [
+        {
+          "href": "/dd",
+          "title": "Home",
+          "hierarchy": ["0"],
+          "machine-name": ["main"]
+        },
+        {
+          "href": "/dd/node/1",
+          "title": "A multi-lingual-node",
+          "hierarchy": ["1"],
+          "machine-name": ["main"]
+        },
+        {
+          "href": "/dd/node/2",
+          "title": "Second multi-lingual-node",
+          "hierarchy": ["2"],
+          "machine-name": ["main"]
+        },
+        {
+          "href": "/dd/node/3",
+          "title": "Third multi-lingual-node",
+          "hierarchy": ["3"],
+          "machine-name": ["main"]
+        }
+      ]
+    }
+  ]
+}

core/modules/system/tests/fixtures/linkset/linkset-menu-main-multilingual-default.json

@@ -0,0 +1,33 @@
+{
+  "linkset": [
+    {
+      "anchor": "/system/menu/main/linkset",
+      "item": [
+        {
+          "href": "/",
+          "title": "Home",
+          "hierarchy": ["0"],
+          "machine-name": ["main"]
+        },
+        {
+          "href": "/node/1",
+          "title": "A multi-lingual-node",
+          "hierarchy": ["1"],
+          "machine-name": ["main"]
+        },
+        {
+          "href": "/node/2",
+          "title": "Second multi-lingual-node",
+          "hierarchy": ["2"],
+          "machine-name": ["main"]
+        },
+        {
+          "href": "/node/3",
+          "title": "Third multi-lingual-node",
+          "hierarchy": ["3"],
+          "machine-name": ["main"]
+        }
+      ]
+    }
+  ]
+}

core/modules/system/tests/fixtures/linkset/linkset-menu-main.json

@@ -0,0 +1,47 @@
+{
+  "linkset": [
+    {
+      "anchor": "/system/menu/main/linkset",
+      "item": [
+        {
+          "href": "/",
+          "title": "Home",
+          "hierarchy": ["0"],
+          "machine-name": ["main"]
+        },
+        {
+          "href": "/about",
+          "title": "About us",
+          "hierarchy": ["1"],
+          "machine-name": ["main"]
+        },
+        {
+          "href": "/about/custom-attributes",
+          "title": "Custom attributes test page",
+          "hierarchy": ["1", "0"],
+          "class": [
+            "foo",
+            "bar",
+            "1729",
+            "1",
+            "",
+            "0",
+            "-1",
+            "3.141592"
+          ],
+          "data-baz": [
+            "42"
+          ],
+          "¯\\_(ツ)_/¯": ["ok"],
+          "machine-name": ["main"]
+        },
+        {
+          "href": "/about/name",
+          "title": "Our name",
+          "hierarchy": ["1","1"],
+          "machine-name": ["main"]
+        }
+      ]
+    }
+  ]
+}

core/modules/system/tests/fixtures/psa_feed/invalid.json

@@ -0,0 +1 @@
+[{"title":"You can't parse this! Oh no! 🔥🙀🐶

core/modules/system/tests/fixtures/psa_feed/valid-mixed.json

@@ -0,0 +1,80 @@
+[
+  {
+    "title":"Critical Release - SA-2019-02-19",
+    "link":"https:\/\/www.drupal.org\/sa-2019-02-19",
+    "project":"drupal",
+    "type":"core",
+    "insecure":[
+      "7.65",
+      "8.5.14",
+      "8.6.13",
+      "8.7.0-alpha2",
+      "8.7.0-beta1",
+      "8.7.0-beta2",
+      "8.6.14",
+      "8.6.15",
+      "7.66",
+      "8.7.0",
+      "[CORE_VERSION]"
+    ],
+    "is_psa":"0",
+    "pubDate":"Tue, 19 Feb 2019 14:11:01 +0000"
+  },
+  {
+    "title":"Critical Release - PSA-Really Old",
+    "link":"https:\/\/www.drupal.org\/psa",
+    "project":"drupal",
+    "type":"core",
+    "is_psa":"1",
+    "insecure":[
+
+    ],
+    "pubDate":"Tue, 19 Feb 2017 14:11:01 +0000"
+  },
+  {
+    "title":"Generic Module1 Project - Moderately critical - Access bypass - SA-CONTRIB-2019-02-02",
+    "link":"https:\/\/www.drupal.org\/SA-CONTRIB-2019-02-02",
+    "project":"generic_module1_project",
+    "type":"module",
+    "is_psa":"0",
+    "insecure":[
+      "8.x-1.1"
+
+    ],
+    "pubDate":"Tue, 19 Mar 2019 12:50:00 +0000"
+  },
+  {
+    "title":"Generic Module1 Test - Moderately critical - Access bypass - SA-CONTRIB-2019-02-02",
+    "link":"https:\/\/www.drupal.org\/SA-CONTRIB-2019-02-02",
+    "project":"generic_module1_test",
+    "type":"module",
+    "is_psa":"0",
+    "insecure":[
+      "8.x-1.1"
+    ],
+    "pubDate":"Tue, 19 Mar 2019 12:50:00 +0000"
+  },
+  {
+    "title":"Generic Module2 project - Moderately critical - Access bypass - SA-CONTRIB-2019-02-02",
+    "link":"https:\/\/www.drupal.org\/SA-CONTRIB-2019-02-02",
+    "project":"generic_module2_project",
+    "type":"module",
+    "is_psa":"1",
+    "insecure":[
+
+    ],
+    "pubDate":"Tue, 19 Mar 2019 12:50:00 +0000"
+  },
+  {
+    "title":"Missing Project - Moderately critical - Access bypass - SA-CONTRIB-2019-02-02",
+    "link":"https:\/\/www.drupal.org\/SA-CONTRIB-2019-02-02",
+    "project":"missing_project",
+    "type":"module",
+    "is_psa":"1",
+    "insecure":[
+      "7.x-1.7",
+      "8.x-1.4"
+    ],
+    "pubDate":"Tue, 19 Mar 2019 12:50:00 +0000"
+  }
+]

core/modules/system/tests/fixtures/psa_feed/valid-non-psa-only.json

@@ -0,0 +1,58 @@
+[
+  {
+    "title":"Critical Release - SA-2019-02-19",
+    "link":"https:\/\/www.drupal.org\/sa-2019-02-19",
+    "project":"drupal",
+    "type":"core",
+    "insecure":[
+      "7.65",
+      "8.5.14",
+      "8.6.13",
+      "8.7.0-alpha2",
+      "8.7.0-beta1",
+      "8.7.0-beta2",
+      "8.6.14",
+      "8.6.15",
+      "7.66",
+      "8.7.0",
+      "[CORE_VERSION]"
+    ],
+    "is_psa":"0",
+    "pubDate":"Tue, 19 Feb 2019 14:11:01 +0000"
+  },
+  {
+    "title":"Generic Module1 Project - Moderately critical - Access bypass - SA-CONTRIB-2019-02-02",
+    "link":"https:\/\/www.drupal.org\/SA-CONTRIB-2019-02-02",
+    "project":"generic_module1_project",
+    "type":"module",
+    "is_psa":"0",
+    "insecure":[
+      "8.x-1.1"
+
+    ],
+    "pubDate":"Tue, 19 Mar 2019 12:50:00 +0000"
+  },
+  {
+    "title":"Generic Module1 Test - Moderately critical - Access bypass - SA-CONTRIB-2019-02-02",
+    "link":"https:\/\/www.drupal.org\/SA-CONTRIB-2019-02-02",
+    "project":"generic_module1_test",
+    "type":"module",
+    "is_psa":"0",
+    "insecure":[
+      "8.x-1.1"
+    ],
+    "pubDate":"Tue, 19 Mar 2019 12:50:00 +0000"
+  },
+  {
+    "title":"Missing Project - Moderately critical - Access bypass - SA-CONTRIB-2019-02-02",
+    "link":"https:\/\/www.drupal.org\/SA-CONTRIB-2019-02-02",
+    "project":"missing_project",
+    "type":"module",
+    "is_psa":"1",
+    "insecure":[
+      "7.x-1.7",
+      "8.x-1.4"
+    ],
+    "pubDate":"Tue, 19 Mar 2019 12:50:00 +0000"
+  }
+]

core/modules/system/tests/fixtures/psa_feed/valid-psa-only.json

@@ -0,0 +1,47 @@
+[
+  {
+    "title":"Critical Release - PSA-Really Old",
+    "link":"https:\/\/www.drupal.org\/psa",
+    "project":"drupal",
+    "type":"core",
+    "is_psa":"1",
+    "insecure":[
+
+    ],
+    "pubDate":"Tue, 19 Feb 2017 14:11:01 +0000"
+  },
+  {
+    "title":"Generic Module1 Test - Moderately critical - Access bypass - SA-CONTRIB-2019-02-02",
+    "link":"https:\/\/www.drupal.org\/SA-CONTRIB-2019-02-02",
+    "project":"generic_module1_test",
+    "type":"module",
+    "is_psa":"0",
+    "insecure":[
+      "8.x-1.1"
+    ],
+    "pubDate":"Tue, 19 Mar 2019 12:50:00 +0000"
+  },
+  {
+    "title":"Generic Module2 project - Moderately critical - Access bypass - SA-CONTRIB-2019-02-02",
+    "link":"https:\/\/www.drupal.org\/SA-CONTRIB-2019-02-02",
+    "project":"generic_module2_project",
+    "type":"module",
+    "is_psa":"1",
+    "insecure":[
+
+    ],
+    "pubDate":"Tue, 19 Mar 2019 12:50:00 +0000"
+  },
+  {
+    "title":"Missing Project - Moderately critical - Access bypass - SA-CONTRIB-2019-02-02",
+    "link":"https:\/\/www.drupal.org\/SA-CONTRIB-2019-02-02",
+    "project":"missing_project",
+    "type":"module",
+    "is_psa":"1",
+    "insecure":[
+      "7.x-1.7",
+      "8.x-1.4"
+    ],
+    "pubDate":"Tue, 19 Mar 2019 12:50:00 +0000"
+  }
+]

core/modules/system/tests/fixtures/psa_feed/valid_plus1.json

@@ -0,0 +1,92 @@
+[
+  {
+    "title":"Critical Release - SA-2019-02-19",
+    "link":"https:\/\/www.drupal.org\/sa-2019-02-19",
+    "project":"drupal",
+    "type":"core",
+    "insecure":[
+      "7.65",
+      "8.5.14",
+      "8.6.13",
+      "8.7.0-alpha2",
+      "8.7.0-beta1",
+      "8.7.0-beta2",
+      "8.6.14",
+      "8.6.15",
+      "7.66",
+      "8.7.0",
+      "[CORE_VERSION]"
+    ],
+    "is_psa":"0",
+    "pubDate":"Tue, 19 Feb 2019 14:11:01 +0000"
+  },
+  {
+    "title":"Critical Release - PSA-Really Old",
+    "link":"https:\/\/www.drupal.org\/psa",
+    "project":"drupal",
+    "type":"core",
+    "is_psa":"1",
+    "insecure":[
+
+    ],
+    "pubDate":"Tue, 19 Feb 2017 14:11:01 +0000"
+  },
+  {
+    "title":"Generic Module1 Project - Moderately critical - Access bypass - SA-CONTRIB-2019-02-02",
+    "link":"https:\/\/www.drupal.org\/SA-CONTRIB-2019-02-02",
+    "project":"generic_module1_project",
+    "type":"module",
+    "is_psa":"0",
+    "insecure":[
+      "8.x-1.1",
+      "8.x-8.7.0"
+    ],
+    "pubDate":"Tue, 19 Mar 2019 12:50:00 +0000"
+  },
+  {
+    "title":"Generic Module1 Test - Moderately critical - Access bypass - SA-CONTRIB-2019-02-02",
+    "link":"https:\/\/www.drupal.org\/SA-CONTRIB-2019-02-02",
+    "project":"generic_module1_test",
+    "type":"module",
+    "is_psa":"0",
+    "insecure":[
+      "8.x-1.1",
+      "8.x-8.7.0"
+    ],
+    "pubDate":"Tue, 19 Mar 2019 12:50:00 +0000"
+  },
+  {
+    "title":"Generic Module2 project - Moderately critical - Access bypass - SA-CONTRIB-2019-02-02",
+    "link":"https:\/\/www.drupal.org\/SA-CONTRIB-2019-02-02",
+    "project":"generic_module2_project",
+    "type":"module",
+    "is_psa":"1",
+    "insecure":[
+
+    ],
+    "pubDate":"Tue, 19 Mar 2019 12:50:00 +0000"
+  },
+  {
+    "title":"Missing Project - Moderately critical - Access bypass - SA-CONTRIB-2019-02-02",
+    "link":"https:\/\/www.drupal.org\/SA-CONTRIB-2019-02-02",
+    "project":"missing_project",
+    "type":"module",
+    "is_psa":"1",
+    "insecure":[
+      "7.x-1.7",
+      "8.x-1.4"
+    ],
+    "pubDate":"Tue, 19 Mar 2019 12:50:00 +0000"
+  },
+  {
+    "title":"Critical Release - PSA because 2020",
+    "link":"https:\/\/www.drupal.org\/psa",
+    "project":"drupal",
+    "type":"core",
+    "is_psa":"1",
+    "insecure":[
+
+    ],
+    "pubDate":"Tue, 19 Feb 2020 14:11:01 +0000"
+  }
+]

core/modules/system/tests/fixtures/update/Y2038-timestamp.php

@@ -0,0 +1,69 @@
+<?php
+
+/**
+ * @file
+ * Contains database additions for testing year 2038 update.
+ */
+
+use Drupal\Core\Database\Database;
+
+// cspell:ignore destid sourceid
+
+$connection = Database::getConnection();
+
+// Add a migrate map table.
+$connection->schema()->createTable('migrate_map_d7_file', [
+  'fields' => [
+    'source_ids_hash' => [
+      'type' => 'varchar',
+      'not null' => TRUE,
+      'length' => '64',
+    ],
+    'sourceid1' => [
+      'type' => 'int',
+      'not null' => TRUE,
+      'size' => 'normal',
+    ],
+    'destid1' => [
+      'type' => 'int',
+      'not null' => FALSE,
+      'size' => 'normal',
+      'unsigned' => TRUE,
+    ],
+    'source_row_status' => [
+      'type' => 'int',
+      'not null' => TRUE,
+      'size' => 'tiny',
+      'default' => '0',
+      'unsigned' => TRUE,
+    ],
+    'rollback_action' => [
+      'type' => 'int',
+      'not null' => TRUE,
+      'size' => 'tiny',
+      'default' => '0',
+      'unsigned' => TRUE,
+    ],
+    'last_imported' => [
+      'type' => 'int',
+      'not null' => TRUE,
+      'size' => 'normal',
+      'default' => '0',
+      'unsigned' => TRUE,
+    ],
+    'hash' => [
+      'type' => 'varchar',
+      'not null' => FALSE,
+      'length' => '64',
+    ],
+  ],
+  'primary key' => [
+    'source_ids_hash',
+  ],
+  'indexes' => [
+    'source' => [
+      'sourceid1',
+    ],
+  ],
+  'mysql_character_set' => 'utf8mb4',
+]);

core/modules/system/tests/fixtures/update/drupal-8.entity-revision-data-cleanup-2869568.php

@@ -0,0 +1,58 @@
+<?php
+
+/**
+ * @file
+ * Provides database changes for testing upgrade path of system_update_8404().
+ *
+ * @see \Drupal\Tests\system\Functional\Update\SqlContentEntityStorageRevisionDataCleanupTest
+ */
+
+use Drupal\Core\Database\Database;
+use Drupal\Core\Language\LanguageInterface;
+
+$connection = Database::getConnection();
+
+// Manually add a record to the node_revision
+$connection->insert('node_field_revision')
+  ->fields([
+    'nid' => 8,
+    'vid' => 8,
+    'langcode' => 'en',
+    'title' => 'Deleted revision',
+    'uid' => 1,
+    'status' => 1,
+    'created' => 1439731773,
+    'changed' => 1439732036,
+    'promote' => 1,
+    'sticky' => 0,
+    'revision_translation_affected' => 1,
+    'default_langcode' => 1,
+    'content_translation_source' => LanguageInterface::LANGCODE_NOT_SPECIFIED,
+    'content_translation_outdated' => 0,
+  ])
+  ->execute();
+
+// Add 100 more rows to test the loop in system_update_10201.
+for ($i = 1; $i <= 100; $i++) {
+  // Ensure that the new nodes use a vid that is greater than the maximum vid
+  // in drupal-9.4.0.filled.standard.php.gz for node id 8.
+  $vid = 10 + $i;
+  $connection->insert('node_field_revision')
+    ->fields([
+      'nid' => 8,
+      'vid' => $vid,
+      'langcode' => 'en',
+      'title' => 'Deleted revision',
+      'uid' => 1,
+      'status' => 1,
+      'created' => 1439732773,
+      'changed' => 1439733036,
+      'promote' => 1,
+      'sticky' => 0,
+      'revision_translation_affected' => 1,
+      'default_langcode' => 1,
+      'content_translation_source' => LanguageInterface::LANGCODE_NOT_SPECIFIED,
+      'content_translation_outdated' => 0,
+    ])
+    ->execute();
+}

core/modules/system/tests/fixtures/update/drupal-8.update-schema-version-int.php

@@ -0,0 +1,21 @@
+<?php
+
+/**
+ * @file
+ * Database to mimic the installation of the update_test_schema module.
+ */
+
+use Drupal\Core\Database\Database;
+
+$connection = Database::getConnection();
+
+// Set the schema version.
+$connection->merge('key_value')
+  ->condition('collection', 'system.schema')
+  ->condition('name', 'update_test_schema')
+  ->fields([
+    'collection' => 'system.schema',
+    'name' => 'update_test_schema',
+    'value' => 's:4:"8901";',
+  ])
+  ->execute();

core/modules/system/tests/fixtures/update/drupal-8.update-test-schema-enabled.php

@@ -0,0 +1,54 @@
+<?php
+
+/**
+ * @file
+ * Partial database to mimic the installation of the update_test_schema module.
+ */
+
+use Drupal\Core\Database\Database;
+
+$connection = Database::getConnection();
+
+// Create the table.
+$connection->schema()->createTable('update_test_schema_table', [
+  'fields' => [
+    'a' => [
+      'type' => 'int',
+      'not null' => TRUE,
+      'size' => 'normal',
+    ],
+    'b' => [
+      'type' => 'blob',
+      'not null' => FALSE,
+      'size' => 'normal',
+    ],
+  ],
+]);
+
+// Set the schema version.
+$connection->merge('key_value')
+  ->condition('collection', 'system.schema')
+  ->condition('name', 'update_test_schema')
+  ->fields([
+    'collection' => 'system.schema',
+    'name' => 'update_test_schema',
+    'value' => 'i:8000;',
+  ])
+  ->execute();
+
+// Update core.extension.
+$extensions = $connection->select('config')
+  ->fields('config', ['data'])
+  ->condition('collection', '')
+  ->condition('name', 'core.extension')
+  ->execute()
+  ->fetchField();
+$extensions = unserialize($extensions);
+$extensions['module']['update_test_schema'] = 8000;
+$connection->update('config')
+  ->fields([
+    'data' => serialize($extensions),
+  ])
+  ->condition('collection', '')
+  ->condition('name', 'core.extension')
+  ->execute();

core/modules/system/tests/fixtures/update/drupal-8.update-test-semver-update-n-enabled.php

@@ -0,0 +1,38 @@
+<?php
+
+/**
+ * @file
+ * Database to mimic the installation of the update_test_semver_update_n module.
+ */
+
+use Drupal\Core\Database\Database;
+
+$connection = Database::getConnection();
+
+// Set the schema version.
+$connection->merge('key_value')
+  ->condition('collection', 'system.schema')
+  ->condition('name', 'update_test_semver_update_n')
+  ->fields([
+    'collection' => 'system.schema',
+    'name' => 'update_test_semver_update_n',
+    'value' => 'i:8000;',
+  ])
+  ->execute();
+
+// Update core.extension.
+$extensions = $connection->select('config')
+  ->fields('config', ['data'])
+  ->condition('collection', '')
+  ->condition('name', 'core.extension')
+  ->execute()
+  ->fetchField();
+$extensions = unserialize($extensions);
+$extensions['module']['update_test_semver_update_n'] = 8000;
+$connection->update('config')
+  ->fields([
+    'data' => serialize($extensions),
+  ])
+  ->condition('collection', '')
+  ->condition('name', 'core.extension')
+  ->execute();

core/modules/system/tests/fixtures/update/drupal.timestamp-formatter-settings-2921810.php

@@ -0,0 +1,139 @@
+<?php
+
+/**
+ * @file
+ * Provides database changes for testing the TimestampFormatter upgrade path.
+ *
+ * @see \Drupal\Tests\system\Functional\Update\TimestampFormatterSettingsUpdateTest
+ */
+
+use Drupal\Core\Database\Database;
+use Drupal\field\Entity\FieldStorageConfig;
+
+$connection = Database::getConnection();
+
+// Add a new timestamp field 'field_foo'.
+$connection->insert('config')
+  ->fields(['collection', 'name', 'data'])->values([
+    'collection' => '',
+    'name' => 'field.storage.node.field_foo',
+    'data' => $field_storage = 'a:16:{s:4:"uuid";s:36:"815278cf-a977-4700-aad9-d58034de0115";s:8:"langcode";s:2:"en";s:6:"status";b:1;s:12:"dependencies";a:1:{s:6:"module";a:1:{i:0;s:4:"node";}}s:2:"id";s:14:"node.field_foo";s:10:"field_name";s:9:"field_foo";s:11:"entity_type";s:4:"node";s:4:"type";s:9:"timestamp";s:8:"settings";a:0:{}s:6:"module";s:4:"core";s:6:"locked";b:0;s:11:"cardinality";i:1;s:12:"translatable";b:1;s:7:"indexes";a:0:{}s:22:"persist_with_no_fields";b:0;s:14:"custom_storage";b:0;}',
+  ])->values([
+    'collection' => '',
+    'name' => 'field.field.node.page.field_foo',
+    'data' => 'a:16:{s:4:"uuid";s:36:"ea669e7e-532e-41ad-9322-13ba6a9901b0";s:8:"langcode";s:2:"en";s:6:"status";b:1;s:12:"dependencies";a:1:{s:6:"config";a:2:{i:0;s:28:"field.storage.node.field_foo";i:1;s:14:"node.type.page";}}s:2:"id";s:19:"node.page.field_foo";s:10:"field_name";s:9:"field_foo";s:11:"entity_type";s:4:"node";s:6:"bundle";s:4:"page";s:5:"label";s:3:"Foo";s:11:"description";s:0:"";s:8:"required";b:0;s:12:"translatable";b:0;s:13:"default_value";a:1:{i:0;a:1:{s:5:"value";i:1511630653;}}s:22:"default_value_callback";s:0:"";s:8:"settings";a:0:{}s:10:"field_type";s:9:"timestamp";}',
+  ])->execute();
+
+$connection->insert('key_value')
+  ->fields(['collection', 'name', 'value'])
+  ->values([
+    'collection' => 'config.entity.key_store.field_config',
+    'name' => 'uuid:ea669e7e-532e-41ad-9322-13ba6a9901b0',
+    'value' => 'a:1:{i:0;s:31:"field.field.node.page.field_foo";}',
+  ])
+  ->values([
+    'collection' => 'config.entity.key_store.field_storage_config',
+    'name' => 'uuid:815278cf-a977-4700-aad9-d58034de0115',
+    'value' => 'a:1:{i:0;s:28:"field.storage.node.field_foo";}',
+  ])
+  ->values([
+    'collection' => 'entity.storage_schema.sql',
+    'name' => 'node.field_schema_data.field_foo',
+    'value' => 'a:2:{s:15:"node__field_foo";a:4:{s:11:"description";s:38:"Data storage for node field field_foo.";s:6:"fields";a:7:{s:6:"bundle";a:5:{s:4:"type";s:13:"varchar_ascii";s:6:"length";i:128;s:8:"not null";b:1;s:7:"default";s:0:"";s:11:"description";s:88:"The field instance bundle to which this row belongs, used when deleting a field instance";}s:7:"deleted";a:5:{s:4:"type";s:3:"int";s:4:"size";s:4:"tiny";s:8:"not null";b:1;s:7:"default";i:0;s:11:"description";s:60:"A boolean indicating whether this data item has been deleted";}s:9:"entity_id";a:4:{s:4:"type";s:3:"int";s:8:"unsigned";b:1;s:8:"not null";b:1;s:11:"description";s:38:"The entity id this data is attached to";}s:11:"revision_id";a:4:{s:4:"type";s:3:"int";s:8:"unsigned";b:1;s:8:"not null";b:1;s:11:"description";s:47:"The entity revision id this data is attached to";}s:8:"langcode";a:5:{s:4:"type";s:13:"varchar_ascii";s:6:"length";i:32;s:8:"not null";b:1;s:7:"default";s:0:"";s:11:"description";s:37:"The language code for this data item.";}s:5:"delta";a:4:{s:4:"type";s:3:"int";s:8:"unsigned";b:1;s:8:"not null";b:1;s:11:"description";s:67:"The sequence number for this data item, used for multi-value fields";}s:15:"field_foo_value";a:2:{s:4:"type";s:3:"int";s:8:"not null";b:1;}}s:11:"primary key";a:4:{i:0;s:9:"entity_id";i:1;s:7:"deleted";i:2;s:5:"delta";i:3;s:8:"langcode";}s:7:"indexes";a:2:{s:6:"bundle";a:1:{i:0;s:6:"bundle";}s:11:"revision_id";a:1:{i:0;s:11:"revision_id";}}}s:24:"node_revision__field_foo";a:4:{s:11:"description";s:50:"Revision archive storage for node field field_foo.";s:6:"fields";a:7:{s:6:"bundle";a:5:{s:4:"type";s:13:"varchar_ascii";s:6:"length";i:128;s:8:"not null";b:1;s:7:"default";s:0:"";s:11:"description";s:88:"The field instance bundle to which this row belongs, used when deleting a field instance";}s:7:"deleted";a:5:{s:4:"type";s:3:"int";s:4:"size";s:4:"tiny";s:8:"not null";b:1;s:7:"default";i:0;s:11:"description";s:60:"A boolean indicating whether this data item has been deleted";}s:9:"entity_id";a:4:{s:4:"type";s:3:"int";s:8:"unsigned";b:1;s:8:"not null";b:1;s:11:"description";s:38:"The entity id this data is attached to";}s:11:"revision_id";a:4:{s:4:"type";s:3:"int";s:8:"unsigned";b:1;s:8:"not null";b:1;s:11:"description";s:47:"The entity revision id this data is attached to";}s:8:"langcode";a:5:{s:4:"type";s:13:"varchar_ascii";s:6:"length";i:32;s:8:"not null";b:1;s:7:"default";s:0:"";s:11:"description";s:37:"The language code for this data item.";}s:5:"delta";a:4:{s:4:"type";s:3:"int";s:8:"unsigned";b:1;s:8:"not null";b:1;s:11:"description";s:67:"The sequence number for this data item, used for multi-value fields";}s:15:"field_foo_value";a:2:{s:4:"type";s:3:"int";s:8:"not null";b:1;}}s:11:"primary key";a:5:{i:0;s:9:"entity_id";i:1;s:11:"revision_id";i:2;s:7:"deleted";i:3;s:5:"delta";i:4;s:8:"langcode";}s:7:"indexes";a:2:{s:6:"bundle";a:1:{i:0;s:6:"bundle";}s:11:"revision_id";a:1:{i:0;s:11:"revision_id";}}}}',
+  ])
+  ->execute();
+
+$data = $connection->select('key_value')
+  ->fields('key_value', ['value'])
+  ->condition('collection', 'entity.definitions.bundle_field_map')
+  ->condition('name', 'node')
+  ->execute()
+  ->fetchField();
+$data = unserialize($data);
+$data['field_foo']['type'] = 'timestamp';
+$data['field_foo']['bundles']['page'] = 'page';
+$connection->update('key_value')
+  ->fields(['value' => serialize($data)])
+  ->condition('collection', 'entity.definitions.bundle_field_map')
+  ->condition('name', 'node')
+  ->execute();
+
+$data = $connection->select('key_value')
+  ->fields('key_value', ['value'])
+  ->condition('collection', 'entity.definitions.installed')
+  ->condition('name', 'node.field_storage_definitions')
+  ->execute()
+  ->fetchField();
+$data = unserialize($data);
+$data['field_foo'] = new FieldStorageConfig(unserialize($field_storage));
+$connection->update('key_value')
+  ->fields(['value' => serialize($data)])
+  ->condition('collection', 'entity.definitions.installed')
+  ->condition('name', 'node.field_storage_definitions')
+  ->execute();
+
+// Add the new field to default entity view display.
+$config = $connection->select('config')
+  ->fields('config', ['data'])
+  ->condition('collection', '')
+  ->condition('name', 'core.entity_view_display.node.page.default')
+  ->execute()
+  ->fetchField();
+$config = unserialize($config);
+$config['content']['field_foo'] = [
+  'type' => 'timestamp',
+  'label' => 'hidden',
+  'weight' => 0,
+  'region' => 'content',
+  'settings' => [
+    'date_format' => 'custom',
+    'custom_date_format' => 'Y-m-d',
+    'timezone' => '',
+  ],
+  'third_party_settings' => [],
+];
+$config['third_party_settings']['layout_builder'] = [
+  'enabled' => TRUE,
+  'allow_custom' => FALSE,
+  'sections' => [
+    [
+      'layout_id' => 'layout_onecol',
+      'layout_settings' => [
+        'label' => '',
+      ],
+      'components' => [
+        '93bf4359-06a6-4263-bce9-15c90dc8f357' => [
+          'uuid' => '93bf4359-06a6-4263-bce9-15c90dc8f357',
+          'region' => 'content',
+          'configuration' => [
+            'id' => 'field_block:node:page:field_foo',
+            'label_display' => '0',
+            'context_mapping' => [
+              'entity' => 'layout_builder.entity',
+            ],
+            'formatter' => [
+              'type' => 'timestamp',
+              'label' => 'inline',
+              'settings' => [
+                'date_format' => 'custom',
+                'custom_date_format' => 'Y-m-d',
+                'timezone' => '',
+              ],
+              'third_party_settings' => [],
+            ],
+          ],
+          'weight' => 0,
+          'additional' => [],
+
+        ],
+      ],
+      'third_party_settings' => [],
+    ],
+  ],
+];
+
+$connection->update('config')
+  ->fields(['data' => serialize($config)])
+  ->condition('collection', '')
+  ->condition('name', 'core.entity_view_display.node.page.default')
+  ->execute();

core/modules/system/tests/http.php

@@ -0,0 +1,30 @@
+<?php
+
+/**
+ * @file
+ * Fake an HTTP request, for use during testing.
+ */
+
+use Drupal\Core\Test\TestKernel;
+use Symfony\Component\HttpFoundation\Request;
+
+chdir('../../../..');
+
+$autoloader = require_once 'autoload.php';
+
+// Change to HTTP.
+$_SERVER['HTTPS'] = NULL;
+ini_set('session.cookie_secure', FALSE);
+foreach ($_SERVER as &$value) {
+  // Because HTTPS is null.
+  $value = $value ? str_replace('core/modules/system/tests/http.php', 'index.php', $value) : "";
+  $value = $value ? str_replace('https://', 'http://', $value) : "";
+}
+
+$kernel = new TestKernel('testing', $autoloader, TRUE);
+
+$request = Request::createFromGlobals();
+$response = $kernel->handle($request);
+$response->send();
+
+$kernel->terminate($request, $response);

core/modules/system/tests/https.php

@@ -0,0 +1,31 @@
+<?php
+
+/**
+ * @file
+ * Fake an HTTPS request, for use during testing.
+ *
+ * @todo Fix this to use a new request rather than modifying server variables,
+ *   see http.php.
+ */
+
+use Drupal\Core\Test\TestKernel;
+use Symfony\Component\HttpFoundation\Request;
+
+chdir('../../../..');
+
+$autoloader = require_once 'autoload.php';
+
+// Change to HTTPS.
+$_SERVER['HTTPS'] = 'on';
+foreach ($_SERVER as &$value) {
+  $value = str_replace('core/modules/system/tests/https.php', 'index.php', $value);
+  $value = str_replace('http://', 'https://', $value);
+}
+
+$kernel = new TestKernel('testing', $autoloader, TRUE);
+
+$request = Request::createFromGlobals();
+$response = $kernel->handle($request);
+$response->send();
+
+$kernel->terminate($request, $response);

core/modules/system/tests/modules/accept_header_routing_test/accept_header_routing_test.info.yml

@@ -0,0 +1,9 @@
+name: Accept header based routing test
+type: module
+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/system/tests/modules/accept_header_routing_test/accept_header_routing_test.services.yml

@@ -0,0 +1,5 @@
+services:
+  accept_header_matcher:
+    class: Drupal\accept_header_routing_test\Routing\AcceptHeaderMatcher
+    tags:
+      - { name: route_filter }

core/modules/system/tests/modules/accept_header_routing_test/src/AcceptHeaderMiddleware.php

@@ -0,0 +1,47 @@
+<?php
+
+namespace Drupal\accept_header_routing_test;
+
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Response;
+use Symfony\Component\HttpKernel\HttpKernelInterface;
+
+/**
+ * Example implementation of "accept header"-based content negotiation.
+ */
+class AcceptHeaderMiddleware implements HttpKernelInterface {
+
+  /**
+   * The app kernel.
+   */
+  protected HttpKernelInterface $app;
+
+  /**
+   * Constructs a new AcceptHeaderMiddleware instance.
+   *
+   * @param \Symfony\Component\HttpKernel\HttpKernelInterface $app
+   *   The app.
+   */
+  public function __construct(HttpKernelInterface $app) {
+    $this->app = $app;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function handle(Request $request, $type = self::MAIN_REQUEST, $catch = TRUE): Response {
+    $mapping = [
+      'application/json' => 'json',
+      'application/xml' => 'xml',
+      'text/html' => 'html',
+    ];
+
+    $accept = $request->headers->get('Accept') ?: ['text/html'];
+    if (isset($mapping[$accept[0]])) {
+      $request->setRequestFormat($mapping[$accept[0]]);
+    }
+
+    return $this->app->handle($request, $type, $catch);
+  }
+
+}

core/modules/system/tests/modules/accept_header_routing_test/src/AcceptHeaderRoutingTestServiceProvider.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace Drupal\accept_header_routing_test;
+
+use Drupal\Core\DependencyInjection\ContainerBuilder;
+use Drupal\Core\DependencyInjection\ServiceModifierInterface;
+
+/**
+ * Service provider for the accept_header_routing_test module.
+ */
+class AcceptHeaderRoutingTestServiceProvider implements ServiceModifierInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function alter(ContainerBuilder $container) {
+    // Remove the basic content negotiation middleware and replace it with a
+    // basic header based one.
+    $container->register('http_middleware.negotiation', 'Drupal\accept_header_routing_test\AcceptHeaderMiddleware')
+      ->addTag('http_middleware', ['priority' => 400]);
+  }
+
+}

core/modules/system/tests/modules/accept_header_routing_test/src/Routing/AcceptHeaderMatcher.php

@@ -0,0 +1,61 @@
+<?php
+
+namespace Drupal\accept_header_routing_test\Routing;
+
+use Drupal\Core\Routing\FilterInterface;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpKernel\Exception\NotAcceptableHttpException;
+use Symfony\Component\Routing\RouteCollection;
+
+/**
+ * Filters routes based on the media type specified in the HTTP Accept headers.
+ */
+class AcceptHeaderMatcher implements FilterInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function filter(RouteCollection $collection, Request $request) {
+    // Generates a list of Symfony formats matching the acceptable MIME types.
+    // @todo replace by proper content negotiation library.
+    $acceptable_mime_types = $request->getAcceptableContentTypes();
+    $acceptable_formats = array_filter(array_map([$request, 'getFormat'], $acceptable_mime_types));
+    $primary_format = $request->getRequestFormat();
+
+    foreach ($collection as $name => $route) {
+      // _format could be a |-delimited list of supported formats.
+      $supported_formats = array_filter(explode('|', $route->getRequirement('_format') ?? ''));
+
+      if (empty($supported_formats)) {
+        // No format restriction on the route, so it always matches. Move it to
+        // the end of the collection by re-adding it.
+        $collection->add($name, $route);
+      }
+      elseif (in_array($primary_format, $supported_formats)) {
+        // Perfect match, which will get a higher priority by leaving the route
+        // on top of the list.
+      }
+      // The route partially matches if it doesn't care about format, if it
+      // explicitly allows any format, or if one of its allowed formats is
+      // in the request's list of acceptable formats.
+      elseif (in_array('*/*', $acceptable_mime_types) || array_intersect($acceptable_formats, $supported_formats)) {
+        // Move it to the end of the list.
+        $collection->add($name, $route);
+      }
+      else {
+        // Remove the route if it does not match at all.
+        $collection->remove($name);
+      }
+    }
+
+    if (count($collection)) {
+      return $collection;
+    }
+
+    // We do not throw a
+    // \Symfony\Component\Routing\Exception\ResourceNotFoundException here
+    // because we don't want to return a 404 status code, but rather a 406.
+    throw new NotAcceptableHttpException('No route found for the specified formats ' . implode(' ', $acceptable_mime_types));
+  }
+
+}

core/modules/system/tests/modules/action_test/action_test.info.yml

@@ -0,0 +1,10 @@
+name: 'Action test'
+type: module
+description: 'Support module for action testing.'
+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/system/tests/modules/action_test/src/Plugin/Action/NoType.php

@@ -0,0 +1,34 @@
+<?php
+
+namespace Drupal\action_test\Plugin\Action;
+
+use Drupal\Core\Access\AccessResult;
+use Drupal\Core\Action\ActionBase;
+use Drupal\Core\Action\Attribute\Action;
+use Drupal\Core\Session\AccountInterface;
+use Drupal\Core\StringTranslation\TranslatableMarkup;
+
+/**
+ * Provides an operation with no type specified.
+ */
+#[Action(
+  id: 'action_test_no_type',
+  label: new TranslatableMarkup('An operation with no type specified'),
+)]
+class NoType extends ActionBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function execute($entity = NULL) {
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function access($object, ?AccountInterface $account = NULL, $return_as_object = FALSE) {
+    $result = AccessResult::allowed();
+    return $return_as_object ? $result : $result->isAllowed();
+  }
+
+}

core/modules/system/tests/modules/action_test/src/Plugin/Action/SaveEntity.php

@@ -0,0 +1,35 @@
+<?php
+
+namespace Drupal\action_test\Plugin\Action;
+
+use Drupal\Core\Action\ActionBase;
+use Drupal\Core\Action\Attribute\Action;
+use Drupal\Core\Session\AccountInterface;
+use Drupal\Core\StringTranslation\TranslatableMarkup;
+
+/**
+ * Provides an operation to save user entities.
+ */
+#[Action(
+  id: 'action_test_save_entity',
+  label: new TranslatableMarkup('Saves entities'),
+  type: 'user'
+)]
+class SaveEntity extends ActionBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function execute($entity = NULL) {
+    $entity->save();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function access($object, ?AccountInterface $account = NULL, $return_as_object = FALSE) {
+    /** @var \Drupal\Core\Entity\EntityInterface $object */
+    return $object->access('update', $account, $return_as_object);
+  }
+
+}

core/modules/system/tests/modules/advisory_feed_test/advisory_feed_test.info.yml

@@ -0,0 +1,9 @@
+name: 'Advisory feed test'
+type: module
+description: 'Support module for advisory feed testing.'
+package: Testing
+
+# Information added by Drupal.org packaging script on 2024-07-04
+version: '10.3.1'
+project: 'drupal'
+datestamp: 1720094222

core/modules/system/tests/modules/advisory_feed_test/advisory_feed_test.module

@@ -0,0 +1,35 @@
+<?php
+
+/**
+ * @file
+ * Module for testing the display of security advisories.
+ */
+
+use Drupal\Core\Extension\Extension;
+
+/**
+ * Implements hook_system_info_alter().
+ */
+function advisory_feed_test_system_info_alter(&$info, Extension $file) {
+  // Alter the 'generic_module1_test' module to use the 'generic_module1_project'
+  // project name.  This ensures that for an extension where the 'name' and
+  // the 'project' properties do not match, 'project' is used for matching
+  // 'project' in the JSON feed.
+  $system_info = [
+    'generic_module1_test' => [
+      'project' => 'generic_module1_project',
+      'version' => '8.x-1.1',
+      'hidden' => FALSE,
+    ],
+    'generic_module2_test' => [
+      'project' => 'generic_module2_project',
+      'version' => '8.x-1.1',
+      'hidden' => FALSE,
+    ],
+  ];
+  if (!empty($system_info[$file->getName()])) {
+    foreach ($system_info[$file->getName()] as $key => $value) {
+      $info[$key] = $value;
+    }
+  }
+}

core/modules/system/tests/modules/advisory_feed_test/advisory_feed_test.routing.yml

@@ -0,0 +1,7 @@
+advisory_feed_test.json_test:
+  path: '/advisory-feed-json/{json_name}'
+  defaults:
+    _title: 'Update test'
+    _controller: '\Drupal\advisory_feed_test\Controller\AdvisoryTestController::getPsaJson'
+  requirements:
+    _access: 'TRUE'

core/modules/system/tests/modules/advisory_feed_test/advisory_feed_test.services.yml

@@ -0,0 +1,10 @@
+services:
+  http_client.advisory_feed_test:
+    class: Drupal\advisory_feed_test\AdvisoryTestClientMiddleware
+    tags:
+      - { name: http_client_middleware }
+  logger.advisory_feed_test:
+    public: false
+    class: Drupal\advisory_feed_test\TestSystemLoggerChannel
+    decorates: logger.channel.system
+    arguments: ['@logger.advisory_feed_test.inner', '@state']

core/modules/system/tests/modules/advisory_feed_test/src/AdvisoryTestClientMiddleware.php

@@ -0,0 +1,47 @@
+<?php
+
+namespace Drupal\advisory_feed_test;
+
+use GuzzleHttp\Promise\PromiseInterface;
+use GuzzleHttp\Psr7\Uri;
+use Psr\Http\Message\RequestInterface;
+
+/**
+ * Overrides the User-Agent HTTP header for outbound HTTP requests.
+ */
+class AdvisoryTestClientMiddleware {
+
+  /**
+   * HTTP middleware that replaces URI for advisory requests.
+   */
+  public function __invoke() {
+    return function ($handler) {
+      return function (RequestInterface $request, array $options) use ($handler): PromiseInterface {
+        $test_end_point = \Drupal::state()->get('advisories_test_endpoint');
+        if ($test_end_point && str_contains($request->getUri(), '://updates.drupal.org/psa.json')) {
+          // Only override $uri if it matches the advisories JSON feed to avoid
+          // changing any other uses of the 'http_client' service during tests with
+          // this module installed.
+          $request = $request->withUri(new Uri($test_end_point));
+        }
+        return $handler($request, $options);
+      };
+    };
+  }
+
+  /**
+   * Sets the test endpoint for the advisories JSON feed.
+   *
+   * @param string $test_endpoint
+   *   The test endpoint.
+   * @param bool $delete_stored_response
+   *   Whether to delete stored feed response.
+   */
+  public static function setTestEndpoint(string $test_endpoint, bool $delete_stored_response = FALSE): void {
+    \Drupal::state()->set('advisories_test_endpoint', $test_endpoint);
+    if ($delete_stored_response) {
+      \Drupal::service('system.sa_fetcher')->deleteStoredResponse();
+    }
+  }
+
+}

core/modules/system/tests/modules/advisory_feed_test/src/Controller/AdvisoryTestController.php

@@ -0,0 +1,39 @@
+<?php
+
+namespace Drupal\advisory_feed_test\Controller;
+
+use Symfony\Component\HttpFoundation\JsonResponse;
+use Symfony\Component\HttpFoundation\Response;
+
+/**
+ * Defines a controller to return JSON for security advisory tests.
+ */
+class AdvisoryTestController {
+
+  /**
+   * Reads a JSON file and returns the contents as a Response.
+   *
+   * This method will replace the string '[CORE_VERSION]' with the current core
+   * version to allow testing core version matches.
+   *
+   * @param string $json_name
+   *   The name of the JSON file without the file extension.
+   *
+   * @return \Symfony\Component\HttpFoundation\JsonResponse|\Symfony\Component\HttpFoundation\Response
+   *   If a fixture file with the name $json_name + '.json' is found a
+   *   JsonResponse will be returned using the contents of the file, otherwise a
+   *   Response will be returned with a 404 status code.
+   */
+  public function getPsaJson(string $json_name): Response {
+    $file = __DIR__ . "/../../../../fixtures/psa_feed/$json_name.json";
+    $headers = ['Content-Type' => 'application/json; charset=utf-8'];
+    if (!is_file($file)) {
+      // Return an empty response.
+      return new Response('', 404, $headers);
+    }
+    $contents = file_get_contents($file);
+    $contents = str_replace('[CORE_VERSION]', \Drupal::VERSION, $contents);
+    return new JsonResponse($contents, 200, $headers, TRUE);
+  }
+
+}

core/modules/system/tests/modules/advisory_feed_test/src/TestSystemLoggerChannel.php

@@ -0,0 +1,56 @@
+<?php
+
+namespace Drupal\advisory_feed_test;
+
+use Drupal\Core\Logger\LoggerChannel;
+use Drupal\Core\Logger\LoggerChannelInterface;
+use Drupal\Core\State\StateInterface;
+use Psr\Log\LogLevel;
+
+/**
+ * Provides a decorator for the 'logger.channel.system' service for testing.
+ */
+final class TestSystemLoggerChannel extends LoggerChannel {
+
+  /**
+   * The decorated logger.channel.system service.
+   *
+   * @var \Drupal\Core\Logger\LoggerChannelInterface
+   */
+  protected $innerLogger;
+
+  /**
+   * The state service.
+   *
+   * @var \Drupal\Core\State\StateInterface
+   */
+  protected $state;
+
+  /**
+   * Constructs an AdvisoriesTestHttpClient object.
+   *
+   * @param \Drupal\Core\Logger\LoggerChannelInterface $inner_logger
+   *   The decorated logger.channel.system service.
+   * @param \Drupal\Core\State\StateInterface $state
+   *   The state service.
+   */
+  public function __construct(LoggerChannelInterface $inner_logger, StateInterface $state) {
+    $this->innerLogger = $inner_logger;
+    $this->state = $state;
+  }
+
+  /**
+   * {@inheritdoc}
+   *
+   * @see \Drupal\Tests\system\Functional\SecurityAdvisories\SecurityAdvisoriesTestTrait::assertServiceAdvisoryLoggedErrors()
+   */
+  public function log($level, $message, array $context = []): void {
+    if ($level === LogLevel::ERROR) {
+      $messages = $this->state->get('advisory_feed_test.error_messages', []);
+      $messages[] = $message;
+      $this->state->set('advisory_feed_test.error_messages', $messages);
+    }
+    $this->innerLogger->log($level, $message, $context);
+  }
+
+}

core/modules/system/tests/modules/ajax_forms_test/ajax_forms_test.info.yml

@@ -0,0 +1,10 @@
+name: 'AJAX form test mock module'
+type: module
+description: 'Test for AJAX form calls.'
+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/system/tests/modules/ajax_forms_test/ajax_forms_test.module

@@ -0,0 +1,262 @@
+<?php
+
+/**
+ * @file
+ * Mock module for Ajax forms testing.
+ */
+
+use Drupal\Core\Ajax\AddCssCommand;
+use Drupal\Core\Ajax\AfterCommand;
+use Drupal\Core\Ajax\AjaxResponse;
+use Drupal\Core\Ajax\AlertCommand;
+use Drupal\Core\Ajax\AnnounceCommand;
+use Drupal\Core\Ajax\AppendCommand;
+use Drupal\Core\Ajax\BeforeCommand;
+use Drupal\Core\Ajax\ChangedCommand;
+use Drupal\Core\Ajax\CssCommand;
+use Drupal\Core\Ajax\DataCommand;
+use Drupal\Core\Ajax\HtmlCommand;
+use Drupal\Core\Ajax\InsertCommand;
+use Drupal\Core\Ajax\InvokeCommand;
+use Drupal\Core\Ajax\PrependCommand;
+use Drupal\Core\Ajax\RemoveCommand;
+use Drupal\Core\Ajax\RestripeCommand;
+use Drupal\Core\Ajax\SettingsCommand;
+use Drupal\Core\Form\FormStateInterface;
+
+/**
+ * Ajax form callback: Selects 'after'.
+ */
+function ajax_forms_test_advanced_commands_after_callback($form, FormStateInterface $form_state) {
+  $selector = '#after_div';
+
+  $response = new AjaxResponse();
+  $response->addCommand(new AfterCommand($selector, "This will be placed after"));
+  return $response;
+}
+
+/**
+ * Ajax form callback: Selects 'alert'.
+ */
+function ajax_forms_test_advanced_commands_alert_callback($form, FormStateInterface $form_state) {
+  $response = new AjaxResponse();
+  $response->addCommand(new AlertCommand('Alert'));
+  return $response;
+}
+
+/**
+ * Ajax form callback: Selects 'announce' with no priority specified.
+ */
+function ajax_forms_test_advanced_commands_announce_callback($form, FormStateInterface $form_state) {
+  return (new AjaxResponse())->addCommand(new AnnounceCommand('Default announcement.'));
+}
+
+/**
+ * Ajax form callback: Selects 'announce' with 'polite' priority.
+ */
+function ajax_forms_test_advanced_commands_announce_polite_callback($form, FormStateInterface $form_state) {
+  return (new AjaxResponse())->addCommand(new AnnounceCommand('Polite announcement.', 'polite'));
+}
+
+/**
+ * Ajax form callback: Selects 'announce' with 'assertive' priority.
+ */
+function ajax_forms_test_advanced_commands_announce_assertive_callback($form, FormStateInterface $form_state) {
+  return (new AjaxResponse())->addCommand(new AnnounceCommand('Assertive announcement.', 'assertive'));
+}
+
+/**
+ * Ajax form callback: Selects 'announce' with two announce commands returned.
+ */
+function ajax_forms_test_advanced_commands_double_announce_callback($form, FormStateInterface $form_state) {
+  return (new AjaxResponse())->addCommand(new AnnounceCommand('Assertive announcement.', 'assertive'))
+    ->addCommand(new AnnounceCommand('Another announcement.'));
+}
+
+/**
+ * Ajax form callback: Selects 'append'.
+ */
+function ajax_forms_test_advanced_commands_append_callback($form, FormStateInterface $form_state) {
+  $selector = '#append_div';
+  $response = new AjaxResponse();
+  $response->addCommand(new AppendCommand($selector, "Appended text"));
+  return $response;
+}
+
+/**
+ * Ajax form callback: Selects 'before'.
+ */
+function ajax_forms_test_advanced_commands_before_callback($form, FormStateInterface $form_state) {
+  $selector = '#before_div';
+  $response = new AjaxResponse();
+  $response->addCommand(new BeforeCommand($selector, "Before text"));
+  return $response;
+}
+
+/**
+ * Ajax form callback: Selects 'changed'.
+ */
+function ajax_forms_test_advanced_commands_changed_callback($form, FormStateInterface $form_state) {
+  $response = new AjaxResponse();
+  $response->addCommand(new ChangedCommand('#changed_div'));
+  return $response;
+}
+
+/**
+ * Ajax form callback: Selects 'changed' with asterisk marking inner div.
+ */
+function ajax_forms_test_advanced_commands_changed_asterisk_callback($form, FormStateInterface $form_state) {
+  $response = new AjaxResponse();
+  $response->addCommand(new ChangedCommand('#changed_div', '#changed_div_mark_this'));
+  return $response;
+}
+
+/**
+ * Ajax form callback: Selects 'css'.
+ */
+function ajax_forms_test_advanced_commands_css_callback($form, FormStateInterface $form_state) {
+  $selector = '#css_div';
+  $color = 'blue';
+
+  $response = new AjaxResponse();
+  $response->addCommand(new CssCommand($selector, ['background-color' => $color]));
+  return $response;
+}
+
+/**
+ * Ajax form callback: Selects 'data'.
+ */
+function ajax_forms_test_advanced_commands_data_callback($form, FormStateInterface $form_state) {
+  $selector = '#data_div';
+  $response = new AjaxResponse();
+  $response->addCommand(new DataCommand($selector, 'test_key', 'test_value'));
+  return $response;
+}
+
+/**
+ * Ajax form callback: Selects 'invoke'.
+ */
+function ajax_forms_test_advanced_commands_invoke_callback($form, FormStateInterface $form_state) {
+  $response = new AjaxResponse();
+  $response->addCommand(new InvokeCommand('#invoke_div', 'addClass', ['error']));
+  return $response;
+}
+
+/**
+ * Ajax form callback: Selects 'html'.
+ */
+function ajax_forms_test_advanced_commands_html_callback($form, FormStateInterface $form_state) {
+  $response = new AjaxResponse();
+  $response->addCommand(new HtmlCommand('#html_div', 'replacement text'));
+  return $response;
+}
+
+/**
+ * Ajax form callback: Selects 'insert'.
+ */
+function ajax_forms_test_advanced_commands_insert_callback($form, FormStateInterface $form_state) {
+  $response = new AjaxResponse();
+  $response->addCommand(new InsertCommand('#insert_div', 'insert replacement text'));
+  return $response;
+}
+
+/**
+ * Ajax form callback: Selects 'prepend'.
+ */
+function ajax_forms_test_advanced_commands_prepend_callback($form, FormStateInterface $form_state) {
+  $response = new AjaxResponse();
+  $response->addCommand(new PrependCommand('#prepend_div', "prepended text"));
+  return $response;
+}
+
+/**
+ * Ajax form callback: Selects 'remove'.
+ */
+function ajax_forms_test_advanced_commands_remove_callback($form, FormStateInterface $form_state) {
+  $response = new AjaxResponse();
+  $response->addCommand(new RemoveCommand('#remove_text'));
+  return $response;
+}
+
+/**
+ * Ajax form callback: Selects 'restripe'.
+ */
+function ajax_forms_test_advanced_commands_restripe_callback($form, FormStateInterface $form_state) {
+  $response = new AjaxResponse();
+  $response->addCommand(new RestripeCommand('#restripe_table'));
+  return $response;
+}
+
+/**
+ * Ajax form callback: Selects 'settings'.
+ */
+function ajax_forms_test_advanced_commands_settings_callback($form, FormStateInterface $form_state) {
+  $setting['ajax_forms_test']['foo'] = 42;
+  $response = new AjaxResponse();
+  $response->addCommand(new SettingsCommand($setting));
+  return $response;
+}
+
+/**
+ * Ajax callback for 'add_css'.
+ */
+function ajax_forms_test_advanced_commands_add_css_callback($form, FormStateInterface $form_state) {
+  $response = new AjaxResponse();
+  $response->addCommand(new AddCssCommand([
+    [
+      'href' => 'my/file.css',
+      'media' => 'all',
+    ],
+    [
+      'href' => 'https://example.com/css?family=Open+Sans',
+      'media' => 'all',
+    ],
+  ]));
+  return $response;
+}
+
+/**
+ * Ajax callback for 'add_css' that uses legacy string parameter.
+ *
+ * @todo Remove in Drupal 11.0.0 https://www.drupal.org/i/3339374
+ */
+function ajax_forms_test_advanced_commands_add_css_legacy_callback($form, FormStateInterface $form_state) {
+  $response = new AjaxResponse();
+  $response->addCommand(new AddCssCommand("<link rel='stylesheet' href='my/file.css' media='all' />"));
+  return $response;
+}
+
+/**
+ * Ajax form callback: Selects the 'driver_text' element of the validation form.
+ */
+function ajax_forms_test_validation_form_callback($form, FormStateInterface $form_state) {
+  \Drupal::messenger()->addStatus("ajax_forms_test_validation_form_callback invoked");
+  \Drupal::messenger()->addStatus(t("Callback: driver_text=%driver_text, spare_required_field=%spare_required_field", ['%driver_text' => $form_state->getValue('driver_text'), '%spare_required_field' => $form_state->getValue('spare_required_field')]));
+  return ['#markup' => '<div id="message_area">ajax_forms_test_validation_form_callback at ' . date('c') . '</div>'];
+}
+
+/**
+ * Ajax form callback: Selects the 'driver_number' element of the validation form.
+ */
+function ajax_forms_test_validation_number_form_callback($form, FormStateInterface $form_state) {
+  \Drupal::messenger()->addStatus("ajax_forms_test_validation_number_form_callback invoked");
+  \Drupal::messenger()->addStatus(t("Callback: driver_number=%driver_number, spare_required_field=%spare_required_field", ['%driver_number' => $form_state->getValue('driver_number'), '%spare_required_field' => $form_state->getValue('spare_required_field')]));
+  return ['#markup' => '<div id="message_area_number">ajax_forms_test_validation_number_form_callback at ' . date('c') . '</div>'];
+}
+
+/**
+ * AJAX form callback: Selects for the ajax_forms_test_lazy_load_form() form.
+ */
+function ajax_forms_test_lazy_load_form_ajax($form, FormStateInterface $form_state) {
+  $build = [
+    '#markup' => 'new content',
+  ];
+
+  if ($form_state->getValue('add_files')) {
+    $build['#attached']['library'][] = 'system/admin';
+    $build['#attached']['library'][] = 'system/drupal.system';
+    $build['#attached']['drupalSettings']['ajax_forms_test_lazy_load_form_submit'] = 'executed';
+  }
+
+  return $build;
+}

core/modules/system/tests/modules/ajax_forms_test/ajax_forms_test.routing.yml

@@ -0,0 +1,55 @@
+ajax_forms_test.get_form:
+  path: '/ajax_forms_test_get_form'
+  defaults:
+    _title: 'AJAX forms simple form test'
+    _form: '\Drupal\ajax_forms_test\Form\AjaxFormsTestSimpleForm'
+  requirements:
+    _access: 'TRUE'
+
+ajax_forms_test.commands_form:
+  path: '/ajax_forms_test_ajax_commands_form'
+  defaults:
+    _title: 'AJAX forms AJAX commands test'
+    _form: '\Drupal\ajax_forms_test\Form\AjaxFormsTestCommandsForm'
+  requirements:
+    _access: 'TRUE'
+
+ajax_forms_test.validation_test:
+  path: '/ajax_validation_test'
+  defaults:
+    _title: 'AJAX Validation Test'
+    _form: '\Drupal\ajax_forms_test\Form\AjaxFormsTestValidationForm'
+  requirements:
+    _access: 'TRUE'
+
+ajax_forms_test.lazy_load_form:
+  path: '/ajax_forms_test_lazy_load_form'
+  defaults:
+    _title: 'AJAX forms lazy load test'
+    _form: '\Drupal\ajax_forms_test\Form\AjaxFormsTestLazyLoadForm'
+  requirements:
+    _access: 'TRUE'
+
+ajax_forms_test.image_button_form:
+  path: '/ajax_forms_image_button_form'
+  defaults:
+    _title: 'AJAX forms image button test'
+    _form: '\Drupal\ajax_forms_test\Form\AjaxFormsTestImageButtonForm'
+  requirements:
+    _access: 'TRUE'
+
+ajax_forms_test.ajax_element_form:
+  path: '/ajax_forms_test_ajax_element_form'
+  defaults:
+    _title: 'AJAX forms elements test'
+    _form: '\Drupal\ajax_forms_test\Form\AjaxFormsTestAjaxElementsForm'
+  requirements:
+    _access: 'TRUE'
+
+ajax_forms_test.dialog_form_link:
+  path: '/ajax_forms_test_dialog_form_link'
+  defaults:
+    _title: 'Dialog form link test'
+    _controller: '\Drupal\ajax_forms_test\Controller\DialogFormLink::makeDialogFormLink'
+  requirements:
+    _access: 'TRUE'

core/modules/system/tests/modules/ajax_forms_test/src/Callbacks.php

@@ -0,0 +1,74 @@
+<?php
+
+namespace Drupal\ajax_forms_test;
+
+use Drupal\Core\Ajax\AjaxResponse;
+use Drupal\Core\Ajax\DataCommand;
+use Drupal\Core\Ajax\HtmlCommand;
+use Drupal\Core\Form\FormStateInterface;
+
+/**
+ * Simple object for testing methods as Ajax callbacks.
+ */
+class Callbacks {
+
+  /**
+   * Ajax callback triggered by select.
+   */
+  public function selectCallback($form, FormStateInterface $form_state) {
+    $response = new AjaxResponse();
+    $response->addCommand(new HtmlCommand('#ajax_selected_color', $form_state->getValue('select')));
+    $response->addCommand(new DataCommand('#ajax_selected_color', 'form_state_value_select', $form_state->getValue('select')));
+    return $response;
+  }
+
+  /**
+   * Ajax callback triggered by date.
+   */
+  public function dateCallback($form, FormStateInterface $form_state) {
+    $response = new AjaxResponse();
+    $date = $form_state->getValue('date');
+    $response->addCommand(new HtmlCommand('#ajax_date_value', sprintf('<div>%s</div>', $date)));
+    $response->addCommand(new DataCommand('#ajax_date_value', 'form_state_value_date', $form_state->getValue('date')));
+    return $response;
+  }
+
+  /**
+   * Ajax callback triggered by datetime.
+   */
+  public function datetimeCallback($form, FormStateInterface $form_state) {
+    $datetime = $form_state->getValue('datetime')['date'] . ' ' . $form_state->getValue('datetime')['time'];
+
+    $response = new AjaxResponse();
+    $response->addCommand(new HtmlCommand('#ajax_datetime_value', sprintf('<div>%s</div>', $datetime)));
+    $response->addCommand(new DataCommand('#ajax_datetime_value', 'form_state_value_datetime', $datetime));
+    return $response;
+  }
+
+  /**
+   * Ajax callback triggered by checkbox.
+   */
+  public function checkboxCallback($form, FormStateInterface $form_state) {
+    $response = new AjaxResponse();
+    $response->addCommand(new HtmlCommand('#ajax_checkbox_value', $form_state->getValue('checkbox') ? 'checked' : 'unchecked'));
+    $response->addCommand(new DataCommand('#ajax_checkbox_value', 'form_state_value_select', (int) $form_state->getValue('checkbox')));
+    return $response;
+  }
+
+  /**
+   * Ajax callback to confirm image button was submitted.
+   */
+  public function imageButtonCallback($form, FormStateInterface $form_state) {
+    $response = new AjaxResponse();
+    $response->addCommand(new HtmlCommand('#ajax_image_button_result', "<div id='ajax-1-more-div'>Something witty!</div>"));
+    return $response;
+  }
+
+  /**
+   * Ajax callback triggered by the checkbox in a #group.
+   */
+  public function checkboxGroupCallback($form, FormStateInterface $form_state) {
+    return $form['checkbox_in_group_wrapper'];
+  }
+
+}

core/modules/system/tests/modules/ajax_forms_test/src/Controller/DialogFormLink.php

@@ -0,0 +1,45 @@
+<?php
+
+namespace Drupal\ajax_forms_test\Controller;
+
+use Drupal\Core\Url;
+
+/**
+ * Test class to create dialog form link.
+ */
+class DialogFormLink {
+
+  /**
+   * Builds an associative array representing a link that opens a dialog.
+   *
+   * @return array
+   *   An associative array of link to a form to be opened.
+   */
+  public function makeDialogFormLink() {
+    return [
+      'dialog' => [
+        '#type' => 'link',
+        '#title' => 'Open form in dialog',
+        '#url' => Url::fromRoute('ajax_forms_test.get_form'),
+        '#attributes' => [
+          'class' => ['use-ajax'],
+          'data-dialog-type' => 'dialog',
+        ],
+      ],
+      'off_canvas' => [
+        '#type' => 'link',
+        '#title' => 'Open form in off canvas dialog',
+        '#url' => Url::fromRoute('ajax_forms_test.get_form'),
+        '#attributes' => [
+          'class' => ['use-ajax'],
+          'data-dialog-type' => 'dialog',
+          'data-dialog-renderer' => 'off_canvas',
+        ],
+      ],
+      '#attached' => [
+        'library' => ['core/drupal.dialog.ajax'],
+      ],
+    ];
+  }
+
+}

core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestAjaxElementsForm.php

@@ -0,0 +1,58 @@
+<?php
+
+namespace Drupal\ajax_forms_test\Form;
+
+use Drupal\Core\Form\FormBase;
+use Drupal\ajax_forms_test\Callbacks;
+use Drupal\Core\Form\FormStateInterface;
+
+/**
+ * Builds a form where each Form API element triggers a simple Ajax callback.
+ *
+ * @internal
+ */
+class AjaxFormsTestAjaxElementsForm extends FormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'ajax_forms_test_ajax_elements_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+    $callback_object = new Callbacks();
+
+    $form['date'] = [
+      '#type' => 'date',
+      '#ajax' => [
+        'callback' => [$callback_object, 'dateCallback'],
+      ],
+      '#suffix' => '<div id="ajax_date_value">No date yet selected</div>',
+    ];
+
+    $form['datetime'] = [
+      '#type' => 'datetime',
+      '#ajax' => [
+        'callback' => [$callback_object, 'datetimeCallback'],
+        'wrapper' => 'ajax_datetime_value',
+      ],
+    ];
+
+    $form['datetime_result'] = [
+      '#type' => 'markup',
+      '#markup' => '<div id="ajax_datetime_value">No datetime selected.</div>',
+    ];
+
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {}
+
+}

core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestCommandsForm.php

@@ -0,0 +1,251 @@
+<?php
+
+namespace Drupal\ajax_forms_test\Form;
+
+use Drupal\Core\Form\FormBase;
+use Drupal\Core\Form\FormStateInterface;
+
+/**
+ * Form constructor for the Ajax Command display form.
+ *
+ * @internal
+ */
+class AjaxFormsTestCommandsForm extends FormBase {
+
+  /**
+   * {@inheritdoc}.
+   */
+  public function getFormId() {
+    return 'ajax_forms_test_ajax_commands_form';
+  }
+
+  /**
+   * {@inheritdoc}.
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+    $form = [];
+
+    // Shows the 'after' command with a callback generating commands.
+    $form['after_command_example'] = [
+      '#value' => $this->t("AJAX 'After': Click to put something after the div"),
+      '#type' => 'submit',
+      '#ajax' => [
+        'callback' => 'ajax_forms_test_advanced_commands_after_callback',
+      ],
+      '#suffix' => '<div id="after_div">Something can be inserted after this</div>',
+    ];
+
+    // Shows the 'alert' command.
+    $form['alert_command_example'] = [
+      '#value' => $this->t("AJAX 'Alert': Click to alert"),
+      '#type' => 'submit',
+      '#ajax' => [
+        'callback' => 'ajax_forms_test_advanced_commands_alert_callback',
+      ],
+    ];
+
+    // Shows the 'announce' command with default priority.
+    $form['announce_command_example'] = [
+      '#value' => $this->t("AJAX 'Announce': Click to announce"),
+      '#type' => 'submit',
+      '#ajax' => [
+        'callback' => 'ajax_forms_test_advanced_commands_announce_callback',
+      ],
+    ];
+
+    // Shows the 'announce' command with 'polite' priority.
+    $form['announce_command_polite_example'] = [
+      '#value' => $this->t("AJAX 'Announce': Click to announce with 'polite' priority"),
+      '#type' => 'submit',
+      '#ajax' => [
+        'callback' => 'ajax_forms_test_advanced_commands_announce_polite_callback',
+      ],
+    ];
+
+    // Shows the 'announce' command with 'assertive' priority.
+    $form['announce_command_assertive_example'] = [
+      '#value' => $this->t("AJAX 'Announce': Click to announce with 'assertive' priority"),
+      '#type' => 'submit',
+      '#ajax' => [
+        'callback' => 'ajax_forms_test_advanced_commands_announce_assertive_callback',
+      ],
+    ];
+
+    // Shows the 'announce' command used twice in one AjaxResponse.
+    $form['announce_command_double_example'] = [
+      '#value' => $this->t("AJAX 'Announce': Click to announce twice"),
+      '#type' => 'submit',
+      '#ajax' => [
+        'callback' => 'ajax_forms_test_advanced_commands_double_announce_callback',
+      ],
+    ];
+
+    // Shows the 'append' command.
+    $form['append_command_example'] = [
+      '#value' => $this->t("AJAX 'Append': Click to append something"),
+      '#type' => 'submit',
+      '#ajax' => [
+        'callback' => 'ajax_forms_test_advanced_commands_append_callback',
+      ],
+      '#suffix' => '<div id="append_div">Append inside this div</div>',
+    ];
+
+    // Shows the 'before' command.
+    $form['before_command_example'] = [
+      '#value' => $this->t("AJAX 'before': Click to put something before the div"),
+      '#type' => 'submit',
+      '#ajax' => [
+        'callback' => 'ajax_forms_test_advanced_commands_before_callback',
+      ],
+      '#suffix' => '<div id="before_div">Insert something before this.</div>',
+    ];
+
+    // Shows the 'changed' command without asterisk.
+    $form['changed_command_example'] = [
+      '#value' => $this->t("AJAX changed: Click to mark div changed."),
+      '#type' => 'submit',
+      '#ajax' => [
+        'callback' => 'ajax_forms_test_advanced_commands_changed_callback',
+      ],
+      '#suffix' => '<div id="changed_div"> <div id="changed_div_mark_this">This div can be marked as changed or not.</div></div>',
+    ];
+    // Shows the 'changed' command adding the asterisk.
+    $form['changed_command_asterisk_example'] = [
+      '#value' => $this->t("AJAX changed: Click to mark div changed with asterisk."),
+      '#type' => 'submit',
+      '#ajax' => [
+        'callback' => 'ajax_forms_test_advanced_commands_changed_asterisk_callback',
+      ],
+    ];
+
+    // Shows the Ajax 'css' command.
+    $form['css_command_example'] = [
+      '#value' => $this->t("Set the '#box' div to be blue."),
+      '#type' => 'submit',
+      '#ajax' => [
+        'callback' => 'ajax_forms_test_advanced_commands_css_callback',
+      ],
+      '#suffix' => '<div id="css_div" style="height: 50px; width: 50px; border: 1px solid black"> box</div>',
+    ];
+
+    // Shows the Ajax 'data' command. But there is no use of this information,
+    // as this would require a javascript client to use the data.
+    $form['data_command_example'] = [
+      '#value' => $this->t("AJAX data command: Issue command."),
+      '#type' => 'submit',
+      '#ajax' => [
+        'callback' => 'ajax_forms_test_advanced_commands_data_callback',
+      ],
+      '#suffix' => '<div id="data_div">Data attached to this div.</div>',
+    ];
+
+    // Shows the Ajax 'invoke' command.
+    $form['invoke_command_example'] = [
+      '#value' => $this->t("AJAX invoke command: Invoke addClass() method."),
+      '#type' => 'submit',
+      '#ajax' => [
+        'callback' => 'ajax_forms_test_advanced_commands_invoke_callback',
+      ],
+      '#suffix' => '<div id="invoke_div">Original contents</div>',
+    ];
+
+    // Shows the Ajax 'html' command.
+    $form['html_command_example'] = [
+      '#value' => $this->t("AJAX html: Replace the HTML in a selector."),
+      '#type' => 'submit',
+      '#ajax' => [
+        'callback' => 'ajax_forms_test_advanced_commands_html_callback',
+      ],
+      '#suffix' => '<div id="html_div">Original contents</div>',
+    ];
+
+    // Shows the Ajax 'insert' command.
+    $form['insert_command_example'] = [
+      '#value' => $this->t("AJAX insert: Let client insert based on #ajax['method']."),
+      '#type' => 'submit',
+      '#ajax' => [
+        'callback' => 'ajax_forms_test_advanced_commands_insert_callback',
+        'method' => 'prepend',
+      ],
+      '#suffix' => '<div id="insert_div">Original contents</div>',
+    ];
+
+    // Shows the Ajax 'prepend' command.
+    $form['prepend_command_example'] = [
+      '#value' => $this->t("AJAX 'prepend': Click to prepend something"),
+      '#type' => 'submit',
+      '#ajax' => [
+        'callback' => 'ajax_forms_test_advanced_commands_prepend_callback',
+      ],
+      '#suffix' => '<div id="prepend_div">Something will be prepended to this div. </div>',
+    ];
+
+    // Shows the Ajax 'remove' command.
+    $form['remove_command_example'] = [
+      '#value' => $this->t("AJAX 'remove': Click to remove text"),
+      '#type' => 'submit',
+      '#ajax' => [
+        'callback' => 'ajax_forms_test_advanced_commands_remove_callback',
+      ],
+      '#suffix' => '<div id="remove_div"><div id="remove_text">text to be removed</div></div>',
+    ];
+
+    // Shows the Ajax 'restripe' command.
+    $form['restripe_command_example'] = [
+      '#type' => 'submit',
+      '#value' => $this->t("AJAX 'restripe' command"),
+      '#ajax' => [
+        'callback' => 'ajax_forms_test_advanced_commands_restripe_callback',
+      ],
+      '#suffix' => '<div id="restripe_div">
+                    <table id="restripe_table" style="border: 1px solid black" >
+                    <tr id="table-first"><td>first row</td></tr>
+                    <tr ><td>second row</td></tr>
+                    </table>
+                    </div>',
+    ];
+
+    // Demonstrates the Ajax 'settings' command. The 'settings' command has
+    // nothing visual to "show", but it can be tested.
+    $form['settings_command_example'] = [
+      '#type' => 'submit',
+      '#value' => $this->t("AJAX 'settings' command"),
+      '#ajax' => [
+        'callback' => 'ajax_forms_test_advanced_commands_settings_callback',
+      ],
+    ];
+
+    // Shows the Ajax 'add_css' command.
+    $form['add_css_command_example'] = [
+      '#type' => 'submit',
+      '#value' => $this->t("AJAX 'add_css' command"),
+      '#ajax' => [
+        'callback' => 'ajax_forms_test_advanced_commands_add_css_callback',
+      ],
+    ];
+
+    // Shows the Ajax 'add_css' command with legacy string parameter.
+    // @todo Remove in Drupal 11.0.0 https://www.drupal.org/i/3339374
+    $form['add_css_legacy_command_example'] = [
+      '#type' => 'submit',
+      '#value' => $this->t("AJAX 'add_css' legacy command"),
+      '#ajax' => [
+        'callback' => 'ajax_forms_test_advanced_commands_add_css_legacy_callback',
+      ],
+    ];
+
+    $form['submit'] = [
+      '#type' => 'submit',
+      '#value' => $this->t('Submit'),
+    ];
+
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}.
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {
+  }
+
+}

core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestImageButtonForm.php

@@ -0,0 +1,50 @@
+<?php
+
+namespace Drupal\ajax_forms_test\Form;
+
+use Drupal\ajax_forms_test\Callbacks;
+use Drupal\Core\Form\FormBase;
+use Drupal\Core\Form\FormStateInterface;
+
+/**
+ * Form builder: Builds a form that has image button with an ajax callback.
+ *
+ * @internal
+ */
+class AjaxFormsTestImageButtonForm extends FormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'ajax_forms_test_image_button_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+    $object = new Callbacks();
+    $form['image_button'] = [
+      '#type' => 'image_button',
+      '#name' => 'image_button',
+      '#src' => 'core/misc/icons/787878/cog.svg',
+      '#attributes' => ['alt' => $this->t('Edit')],
+      '#op' => 'edit',
+      '#ajax' => [
+        'callback' => [$object, 'imageButtonCallback'],
+      ],
+      '#suffix' => '<div id="ajax_image_button_result">Image button not pressed yet.</div>',
+    ];
+
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {
+    // No submit code needed.
+  }
+
+}

core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestLazyLoadForm.php

@@ -0,0 +1,56 @@
+<?php
+
+namespace Drupal\ajax_forms_test\Form;
+
+use Drupal\Core\Form\FormBase;
+use Drupal\Core\Form\FormStateInterface;
+
+/**
+ * Form builder: Builds a form that triggers a simple AJAX callback.
+ *
+ * @internal
+ */
+class AjaxFormsTestLazyLoadForm extends FormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'ajax_forms_test_lazy_load_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+    // We attach a JavaScript setting, so that one of the generated AJAX
+    // commands will be a settings command. We can then check the settings
+    // command to ensure that the 'currentPath' setting is not part
+    // of the Ajax response.
+    $form['#attached']['drupalSettings']['test'] = 'currentPathUpdate';
+    $form['add_files'] = [
+      '#title' => $this->t('Add files'),
+      '#type' => 'checkbox',
+      '#default_value' => FALSE,
+    ];
+    $form['submit'] = [
+      '#type' => 'submit',
+      '#value' => $this->t('Submit'),
+      '#ajax' => [
+        'wrapper' => 'ajax-forms-test-lazy-load-ajax-wrapper',
+        'callback' => 'ajax_forms_test_lazy_load_form_ajax',
+      ],
+      '#prefix' => '<div id="ajax-forms-test-lazy-load-ajax-wrapper"></div>',
+    ];
+
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {
+    $form_state->setRebuild();
+  }
+
+}

core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestSimpleForm.php

@@ -0,0 +1,157 @@
+<?php
+
+namespace Drupal\ajax_forms_test\Form;
+
+use Drupal\Core\Form\FormBase;
+use Drupal\ajax_forms_test\Callbacks;
+use Drupal\Core\Form\FormStateInterface;
+
+/**
+ * Form builder: Builds a form that triggers a simple AJAX callback.
+ *
+ * @internal
+ */
+class AjaxFormsTestSimpleForm extends FormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'ajax_forms_test_simple_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+    $object = new Callbacks();
+
+    $form = [];
+    $form['select'] = [
+      '#title' => $this->t('Color'),
+      '#type' => 'select',
+      '#options' => [
+        'red' => 'red',
+        'green' => 'green',
+        'blue' => 'blue',
+      ],
+      '#ajax' => [
+        'callback' => [$object, 'selectCallback'],
+      ],
+      '#suffix' => '<div id="ajax_selected_color">No color yet selected</div>',
+    ];
+
+    $form['checkbox'] = [
+      '#type' => 'checkbox',
+      '#title' => $this->t('Test checkbox'),
+      '#ajax' => [
+        'callback' => [$object, 'checkboxCallback'],
+      ],
+      '#suffix' => '<div id="ajax_checkbox_value">No action yet</div>',
+    ];
+    $form['submit'] = [
+      '#type' => 'submit',
+      '#value' => $this->t('submit'),
+    ];
+
+    // This is for testing invalid callbacks that should return a 500 error in
+    // \Drupal\Core\Form\FormAjaxResponseBuilderInterface::buildResponse().
+    $invalid_callbacks = [
+      'null' => NULL,
+      'empty' => '',
+      'nonexistent' => 'some_function_that_does_not_exist',
+    ];
+    foreach ($invalid_callbacks as $key => $value) {
+      $form['select_' . $key . '_callback'] = [
+        '#type' => 'select',
+        '#title' => $this->t('Test %key callbacks', ['%key' => $key]),
+        '#options' => ['red' => 'red', 'green' => 'green'],
+        '#ajax' => ['callback' => $value],
+      ];
+    }
+
+    $form['test_group'] = [
+      '#type' => 'details',
+      '#title' => $this->t('Test group'),
+      '#open' => TRUE,
+    ];
+
+    // Test ajax element in a #group.
+    $form['checkbox_in_group_wrapper'] = [
+      '#type' => 'container',
+      '#attributes' => ['id' => 'checkbox-wrapper'],
+      '#group' => 'test_group',
+      'checkbox_in_group' => [
+        '#type' => 'checkbox',
+        '#title' => $this->t('AJAX checkbox in a group'),
+        '#ajax' => [
+          'callback' => [$object, 'checkboxGroupCallback'],
+          'wrapper' => 'checkbox-wrapper',
+        ],
+      ],
+      'nested_group' => [
+        '#type' => 'details',
+        '#title' => $this->t('Nested group'),
+        '#open' => TRUE,
+      ],
+      'checkbox_in_nested' => [
+        '#type' => 'checkbox',
+        '#group' => 'nested_group',
+        '#title' => $this->t('AJAX checkbox in a nested group'),
+        '#ajax' => [
+          'callback' => [$object, 'checkboxGroupCallback'],
+          'wrapper' => 'checkbox-wrapper',
+        ],
+      ],
+    ];
+
+    $form['another_checkbox_in_nested'] = [
+      '#type' => 'checkbox',
+      '#group' => 'nested_group',
+      '#title' => $this->t('Another AJAX checkbox in a nested group'),
+    ];
+
+    $form['textfield_focus_tests'] = [
+      '#type' => 'details',
+      '#title' => $this->t('Test group 2'),
+      '#open' => TRUE,
+    ];
+    $form['textfield_focus_tests']['textfield'] = [
+      '#type' => 'textfield',
+      '#title' => 'Textfield 1',
+      '#ajax' => [
+        'callback' => [static::class, 'textfieldCallback'],
+      ],
+    ];
+    $form['textfield_focus_tests']['textfield_2'] = [
+      '#type' => 'textfield',
+      '#title' => 'Textfield 2',
+      '#ajax' => [
+        'callback' => [static::class, 'textfieldCallback'],
+        'event' => 'change',
+        'refocus-blur' => FALSE,
+      ],
+    ];
+    $form['textfield_focus_tests']['textfield_3'] = [
+      '#type' => 'textfield',
+      '#title' => 'Textfield 3',
+      '#ajax' => [
+        'callback' => [static::class, 'textfieldCallback'],
+        'event' => 'change',
+      ],
+    ];
+
+    return $form;
+  }
+
+  public static function textfieldCallback($form) {
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {
+  }
+
+}

core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestValidationForm.php

@@ -0,0 +1,73 @@
+<?php
+
+namespace Drupal\ajax_forms_test\Form;
+
+use Drupal\Core\Form\FormBase;
+use Drupal\Core\Form\FormStateInterface;
+
+/**
+ * Form builder: Builds a form that triggers a simple AJAX callback.
+ *
+ * @internal
+ */
+class AjaxFormsTestValidationForm extends FormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'ajax_forms_test_validation_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+    $form['driver_text'] = [
+      '#title' => $this->t('AJAX-enabled textfield.'),
+      '#description' => $this->t("When this one AJAX-triggers and the spare required field is empty, you should not get an error."),
+      '#type' => 'textfield',
+      '#default_value' => $form_state->getValue('driver_text', ''),
+      '#ajax' => [
+        'callback' => 'ajax_forms_test_validation_form_callback',
+        'wrapper' => 'message_area',
+        'method' => 'replaceWith',
+      ],
+      '#suffix' => '<div id="message_area"></div>',
+    ];
+
+    $form['driver_number'] = [
+      '#title' => $this->t('AJAX-enabled number field.'),
+      '#description' => $this->t("When this one AJAX-triggers and the spare required field is empty, you should not get an error."),
+      '#type' => 'number',
+      '#default_value' => $form_state->getValue('driver_number', ''),
+      '#ajax' => [
+        'callback' => 'ajax_forms_test_validation_number_form_callback',
+        'wrapper' => 'message_area_number',
+        'method' => 'replaceWith',
+      ],
+      '#suffix' => '<div id="message_area_number"></div>',
+    ];
+
+    $form['spare_required_field'] = [
+      '#title' => $this->t("Spare Required Field"),
+      '#type' => 'textfield',
+      '#required' => TRUE,
+    ];
+
+    $form['submit'] = [
+      '#type' => 'submit',
+      '#value' => $this->t('Submit'),
+    ];
+
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {
+    $this->messenger()->addStatus($this->t("Validation form submitted"));
+  }
+
+}

core/modules/system/tests/modules/ajax_forms_test/src/Plugin/Block/AjaxFormBlock.php

@@ -0,0 +1,148 @@
+<?php
+
+namespace Drupal\ajax_forms_test\Plugin\Block;
+
+use Drupal\Core\Block\Attribute\Block;
+use Drupal\Core\Block\BlockBase;
+use Drupal\Core\Form\FormBuilderInterface;
+use Drupal\Core\Form\FormInterface;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Messenger\MessengerInterface;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\Core\StringTranslation\TranslatableMarkup;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Provides an AJAX form block.
+ */
+#[Block(
+  id: "ajax_forms_test_block",
+  admin_label: new TranslatableMarkup("AJAX test form"),
+  category: new TranslatableMarkup("Forms")
+)]
+class AjaxFormBlock extends BlockBase implements FormInterface, ContainerFactoryPluginInterface {
+
+  /**
+   * The form builder.
+   *
+   * @var \Drupal\Core\Form\FormBuilderInterface
+   */
+  protected $formBuilder;
+
+  /**
+   * The messenger.
+   *
+   * @var \Drupal\Core\Messenger\MessengerInterface
+   */
+  protected $messenger;
+
+  /**
+   * Constructs a new AjaxFormBlock.
+   *
+   * @param array $configuration
+   *   A configuration array containing information about the plugin instance.
+   * @param string $plugin_id
+   *   The plugin ID for the plugin instance.
+   * @param mixed $plugin_definition
+   *   The plugin implementation definition.
+   * @param \Drupal\Core\Form\FormBuilderInterface $form_builder
+   *   The form builder.
+   * @param \Drupal\Core\Messenger\MessengerInterface $messenger
+   *   The messenger.
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, FormBuilderInterface $form_builder, MessengerInterface $messenger) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition);
+    $this->formBuilder = $form_builder;
+    $this->messenger = $messenger;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $container->get('form_builder'),
+      $container->get('messenger')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function build() {
+    return $this->formBuilder->getForm($this);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'ajax_forms_test_block';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+    $form['test1'] = [
+      '#type' => 'select',
+      '#title' => $this->t('Test 1'),
+      '#required' => TRUE,
+      '#options' => [
+        'option1' => $this->t('Option 1'),
+        'option2' => $this->t('Option 2'),
+      ],
+      '#ajax' => [
+        'callback' => '::updateOptions',
+        'wrapper' => 'edit-test1-wrapper',
+      ],
+      '#prefix' => '<div id="edit-test1-wrapper">',
+      '#suffix' => '</div>',
+    ];
+    $form['actions'] = [
+      '#type' => 'actions',
+    ];
+    $form['actions']['submit'] = [
+      '#type' => 'submit',
+      '#value' => $this->t('Submit'),
+    ];
+    return $form;
+  }
+
+  /**
+   * Updates the options of a select list.
+   *
+   * @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.
+   *
+   * @return array
+   *   The updated form element.
+   */
+  public function updateOptions(array $form, FormStateInterface $form_state) {
+    $form['test1']['#options']['option1'] = $this->t('Option 1!!!');
+    $form['test1']['#options'] += [
+      'option3' => $this->t('Option 3'),
+      'option4' => $this->t('Option 4'),
+    ];
+    return $form['test1'];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validateForm(array &$form, FormStateInterface $form_state) {
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {
+    $this->messenger->addStatus('Submission successful.');
+  }
+
+}

core/modules/system/tests/modules/ajax_test/ajax_test.info.yml

@@ -0,0 +1,12 @@
+name: 'AJAX Test'
+type: module
+description: 'Support module for AJAX framework tests.'
+package: Testing
+# version: VERSION
+dependencies:
+  - drupal:contact
+
+# Information added by Drupal.org packaging script on 2024-07-04
+version: '10.3.1'
+project: 'drupal'
+datestamp: 1720094222

core/modules/system/tests/modules/ajax_test/ajax_test.libraries.yml

@@ -0,0 +1,50 @@
+ajax_insert:
+  js:
+    js/insert-ajax.js: {}
+  dependencies:
+    - core/drupal.ajax
+order:
+  drupalSettings:
+    ajax: test
+  dependencies:
+    - ajax_test/order-css-command
+    - ajax_test/order-footer-js-command
+    - ajax_test/order-header-js-command
+
+order-css-command:
+  css:
+    theme:
+      # Two CSS files (order should remain the same).
+      a.css: {}
+      b.css: {}
+
+order-footer-js-command:
+  js:
+    footer.js: {}
+
+order-header-js-command:
+  header: true
+  js:
+    header.js: {}
+
+focus.first:
+  js:
+    js/focus-ajax.js: {}
+  dependencies:
+    - core/drupal
+    - core/once
+
+command_promise:
+  version: VERSION
+  js:
+    js/command_promise-ajax.js: {}
+  dependencies:
+    - core/jquery
+    - core/drupal
+    - core/drupal.ajax
+
+global_events:
+  js:
+    js/global_events.js: {}
+  dependencies:
+    - core/drupal.ajax

core/modules/system/tests/modules/ajax_test/ajax_test.routing.yml

@@ -0,0 +1,147 @@
+ajax_test.dialog_contents:
+  path: '/ajax-test/dialog-contents'
+  defaults:
+    _title: 'AJAX Dialog contents routing'
+    _controller: '\Drupal\ajax_test\Controller\AjaxTestController::dialogContents'
+  requirements:
+    _access: 'TRUE'
+
+ajax_test.ajax_render_types:
+  path: '/ajax-test/dialog-contents-types/{type}'
+  defaults:
+    _title: 'AJAX Dialog contents routing'
+    _controller: '\Drupal\ajax_test\Controller\AjaxTestController::renderTypes'
+  requirements:
+    _access: 'TRUE'
+
+ajax_test.dialog_form:
+  path: '/ajax-test/dialog-form'
+  defaults:
+    _title: 'Ajax Form contents'
+    _form: '\Drupal\ajax_test\Form\AjaxTestForm'
+  requirements:
+    _access: 'TRUE'
+
+ajax_test.dialog:
+  path: '/ajax-test/dialog'
+  defaults:
+    _controller: '\Drupal\ajax_test\Controller\AjaxTestController::dialog'
+  requirements:
+    _access: 'TRUE'
+
+ajax_test.insert_links_block_wrapper:
+  path: '/ajax-test/insert-block-wrapper'
+  defaults:
+    _controller: '\Drupal\ajax_test\Controller\AjaxTestController::insertLinksBlockWrapper'
+  requirements:
+    _access: 'TRUE'
+
+ajax_test.insert_links_inline_wrapper:
+  path: '/ajax-test/insert-inline-wrapper'
+  defaults:
+    _controller: '\Drupal\ajax_test\Controller\AjaxTestController::insertLinksInlineWrapper'
+  requirements:
+    _access: 'TRUE'
+
+ajax_test.dialog_close:
+  path: '/ajax-test/dialog-close'
+  defaults:
+    _controller: '\Drupal\ajax_test\Controller\AjaxTestController::dialogClose'
+  requirements:
+    _access: 'TRUE'
+
+ajax_test.render:
+  path: '/ajax-test/render'
+  defaults:
+    _controller: '\Drupal\ajax_test\Controller\AjaxTestController::render'
+  requirements:
+    _access: 'TRUE'
+
+ajax_test.admin.theme:
+  path: '/admin/ajax-test/theme'
+  defaults:
+    _controller: '\Drupal\ajax_test\Controller\AjaxTestController::theme'
+  requirements:
+    _access: 'TRUE'
+
+ajax_test.order:
+  path: '/ajax-test/order'
+  defaults:
+    _controller: '\Drupal\ajax_test\Controller\AjaxTestController::order'
+  requirements:
+    _access: 'TRUE'
+
+ajax_test.render_error:
+  path: '/ajax-test/render-error'
+  defaults:
+    _controller: '\Drupal\ajax_test\Controller\AjaxTestController::renderError'
+  requirements:
+    _access: 'TRUE'
+
+ajax_test.message_form:
+  path: '/ajax-test/message'
+  defaults:
+    _title: 'Ajax Message Form'
+    _form: '\Drupal\ajax_test\Form\AjaxTestMessageCommandForm'
+  requirements:
+    _access: 'TRUE'
+
+ajax_test.focus_first_form:
+  path: '/ajax-test/focus-first'
+  defaults:
+    _title: 'Ajax Focus First Form'
+    _form: '\Drupal\ajax_test\Form\AjaxTestFocusFirstForm'
+  requirements:
+    _access: 'TRUE'
+
+ajax_test.promise:
+  path: '/ajax-test/promise-form'
+  defaults:
+    _title: 'Ajax Form Command Promise'
+    _form: '\Drupal\ajax_test\Form\AjaxTestFormPromise'
+  requirements:
+    _access: 'TRUE'
+
+ajax_test.global_events:
+  path: '/ajax-test/global-events'
+  defaults:
+    _controller: '\Drupal\ajax_test\Controller\AjaxTestController::globalEvents'
+  requirements:
+    _access: 'TRUE'
+
+ajax_test.global_events_clear_log:
+  path: '/ajax-test/global-events/clear-log'
+  defaults:
+    _controller: '\Drupal\ajax_test\Controller\AjaxTestController::globalEventsClearLog'
+  requirements:
+    _access: 'TRUE'
+
+ajax_test.exception_link:
+  path: '/ajax-test/exception-link'
+  defaults:
+    _controller: '\Drupal\ajax_test\Controller\AjaxTestController::exceptionLink'
+  requirements:
+    _access: 'TRUE'
+
+ajax_test.throw_exception:
+  path: '/ajax-test/throw-exception'
+  defaults:
+    _controller: '\Drupal\ajax_test\Controller\AjaxTestController::throwException'
+  requirements:
+    _access: 'TRUE'
+
+ajax_test.http_methods:
+  path: '/ajax-test/http-methods'
+  defaults:
+    _controller: Drupal\ajax_test\Controller\AjaxTestController::httpMethods
+  requirements:
+    _access: 'TRUE'
+  options:
+    no_cache: TRUE
+
+ajax_test.http_methods.dialog:
+  path: '/ajax-test/http-methods-dialog'
+  defaults:
+    _controller: Drupal\ajax_test\Controller\AjaxTestController::httpMethodsDialog
+  requirements:
+    _access: 'TRUE'

core/modules/system/tests/modules/ajax_test/js/command_promise-ajax.js

@@ -0,0 +1,31 @@
+/**
+ * @file
+ *  Testing behavior for the add_js command.
+ */
+
+(($, Drupal) => {
+  /**
+   * Test Ajax execution Order.
+   *
+   * @param {Drupal.Ajax} [ajax]
+   *   {@link Drupal.Ajax} object created by {@link Drupal.Ajax}.
+   * @param {object} response
+   *   The response from the Ajax request.
+   * @param {string} response.selector
+   *   A jQuery selector string.
+   *
+   * @return {Promise}
+   *  The promise that will resolve once this command has finished executing.
+   */
+  Drupal.AjaxCommands.prototype.ajaxCommandReturnPromise = function (
+    ajax,
+    response,
+  ) {
+    return new Promise((resolve, reject) => {
+      setTimeout(() => {
+        this.insert(ajax, response);
+        resolve();
+      }, Math.random() * 500);
+    });
+  };
+})(jQuery, Drupal);

core/modules/system/tests/modules/ajax_test/js/focus-ajax.js

@@ -0,0 +1,23 @@
+/**
+ * @file
+ * For testing FocusFirstCommand.
+ */
+
+((Drupal) => {
+  Drupal.behaviors.focusFirstTest = {
+    attach() {
+      // Add data-has-focus attribute to focused elements so tests have a
+      // selector to wait for before moving to the next test step.
+      once('focusin', document.body).forEach((element) => {
+        element.addEventListener('focusin', (e) => {
+          document
+            .querySelectorAll('[data-has-focus]')
+            .forEach((wasFocused) => {
+              wasFocused.removeAttribute('data-has-focus');
+            });
+          e.target.setAttribute('data-has-focus', true);
+        });
+      });
+    },
+  };
+})(Drupal, once);

core/modules/system/tests/modules/ajax_test/js/global_events.js

@@ -0,0 +1,14 @@
+/**
+ * @file
+ * For testing that jQuery's ajaxSuccess, ajaxComplete, and ajaxStop events
+ * are triggered only after commands in a Drupal Ajax response are executed.
+ */
+
+(($, Drupal) => {
+  ['ajaxSuccess', 'ajaxComplete', 'ajaxStop'].forEach((eventName) => {
+    $(document)[eventName](() => {
+      $('#test_global_events_log').append(eventName);
+      $('#test_global_events_log2').append(eventName);
+    });
+  });
+})(jQuery, Drupal);

core/modules/system/tests/modules/ajax_test/js/insert-ajax.js

@@ -0,0 +1,41 @@
+/**
+ * @file
+ * Drupal behavior to attach click event handlers to ajax-insert and
+ * ajax-insert-inline links for testing ajax requests.
+ */
+
+(function ($, window, Drupal) {
+  Drupal.behaviors.insertTest = {
+    attach(context) {
+      $(once('ajax-insert', '.ajax-insert')).on('click', (event) => {
+        event.preventDefault();
+        const ajaxSettings = {
+          url: event.currentTarget.getAttribute('href'),
+          wrapper: 'ajax-target',
+          base: false,
+          element: false,
+          method: event.currentTarget.getAttribute('data-method'),
+          effect: event.currentTarget.getAttribute('data-effect'),
+        };
+        const myAjaxObject = Drupal.ajax(ajaxSettings);
+        myAjaxObject.execute();
+      });
+
+      $(once('ajax-insert', '.ajax-insert-inline')).on('click', (event) => {
+        event.preventDefault();
+        const ajaxSettings = {
+          url: event.currentTarget.getAttribute('href'),
+          wrapper: 'ajax-target-inline',
+          base: false,
+          element: false,
+          method: event.currentTarget.getAttribute('data-method'),
+          effect: event.currentTarget.getAttribute('data-effect'),
+        };
+        const myAjaxObject = Drupal.ajax(ajaxSettings);
+        myAjaxObject.execute();
+      });
+
+      $(context).addClass('processed');
+    },
+  };
+})(jQuery, window, Drupal);

core/modules/system/tests/modules/ajax_test/src/Ajax/AjaxTestCommandReturnPromise.php

@@ -0,0 +1,26 @@
+<?php
+
+namespace Drupal\ajax_test\Ajax;
+
+use Drupal\Core\Ajax\AppendCommand;
+
+/**
+ * Test Ajax command.
+ */
+class AjaxTestCommandReturnPromise extends AppendCommand {
+
+  /**
+   * Implements Drupal\Core\Ajax\CommandInterface:render().
+   */
+  public function render() {
+
+    return [
+      'command' => 'ajaxCommandReturnPromise',
+      'method' => 'append',
+      'selector' => $this->selector,
+      'data' => $this->getRenderedContent(),
+      'settings' => $this->settings,
+    ];
+  }
+
+}

core/modules/system/tests/modules/ajax_test/src/Controller/AjaxTestController.php

@@ -0,0 +1,460 @@
+<?php
+
+namespace Drupal\ajax_test\Controller;
+
+use Drupal\Component\Serialization\Json;
+use Drupal\Core\Ajax\AjaxResponse;
+use Drupal\Core\Ajax\AlertCommand;
+use Drupal\Core\Ajax\CloseDialogCommand;
+use Drupal\Core\Ajax\HtmlCommand;
+use Drupal\Core\Url;
+use Symfony\Component\HttpFoundation\Request;
+
+/**
+ * Provides content for dialog tests.
+ */
+class AjaxTestController {
+
+  /**
+   * Example content for dialog testing.
+   *
+   * @return array
+   *   Renderable array of AJAX dialog contents.
+   */
+  public static function dialogContents() {
+    // This is a regular render array; the keys do not have special meaning.
+    $content = [
+      '#title' => '<em>AJAX Dialog & contents</em>',
+      'content' => [
+        '#markup' => 'Example message',
+      ],
+      'cancel' => [
+        '#type' => 'link',
+        '#title' => 'Cancel',
+        '#url' => Url::fromRoute('<front>'),
+        '#attributes' => [
+          // This is a special class to which JavaScript assigns dialog closing
+          // behavior.
+          'class' => ['dialog-cancel'],
+        ],
+      ],
+    ];
+
+    return $content;
+  }
+
+  /**
+   * Example content for testing the wrapper of the response.
+   *
+   * @param string $type
+   *   Type of response.
+   *
+   * @return array
+   *   Renderable array of AJAX response contents.
+   */
+  public function renderTypes($type) {
+    return [
+      '#title' => '<em>AJAX Dialog & contents</em>',
+      'content' => [
+        '#type' => 'inline_template',
+        '#template' => $this->getRenderTypes()[$type]['render'],
+      ],
+    ];
+  }
+
+  /**
+   * Returns a render array of links that directly Drupal.ajax().
+   *
+   * @return array
+   *   Renderable array of AJAX response contents.
+   */
+  public function insertLinksBlockWrapper() {
+    $methods = [
+      'html',
+      'replaceWith',
+    ];
+
+    $build['links'] = [
+      'ajax_target' => [
+        '#markup' => '<div class="ajax-target-wrapper"><div id="ajax-target">Target</div></div>',
+      ],
+      'links' => [
+        '#theme' => 'links',
+        '#attached' => ['library' => ['ajax_test/ajax_insert']],
+      ],
+    ];
+    foreach ($methods as $method) {
+      foreach ($this->getRenderTypes() as $type => $item) {
+        $class = 'ajax-insert';
+        $build['links']['links']['#links']["$method-$type"] = [
+          'title' => "Link $method $type",
+          'url' => Url::fromRoute('ajax_test.ajax_render_types', ['type' => $type]),
+          'attributes' => [
+            'class' => [$class],
+            'data-method' => $method,
+            'data-effect' => $item['effect'],
+          ],
+        ];
+      }
+    }
+    return $build;
+  }
+
+  /**
+   * Returns a render array of links that directly Drupal.ajax().
+   *
+   * @return array
+   *   Renderable array of AJAX response contents.
+   */
+  public function insertLinksInlineWrapper() {
+    $methods = [
+      'html',
+      'replaceWith',
+    ];
+
+    $build['links'] = [
+      'ajax_target' => [
+        '#markup' => '<div class="ajax-target-wrapper"><span id="ajax-target-inline">Target inline</span></div>',
+      ],
+      'links' => [
+        '#theme' => 'links',
+        '#attached' => ['library' => ['ajax_test/ajax_insert']],
+      ],
+    ];
+    foreach ($methods as $method) {
+      foreach ($this->getRenderTypes() as $type => $item) {
+        $class = 'ajax-insert-inline';
+        $build['links']['links']['#links']["$method-$type"] = [
+          'title' => "Link $method $type",
+          'url' => Url::fromRoute('ajax_test.ajax_render_types', ['type' => $type]),
+          'attributes' => [
+            'class' => [$class],
+            'data-method' => $method,
+            'data-effect' => $item['effect'],
+          ],
+        ];
+      }
+    }
+    return $build;
+  }
+
+  /**
+   * Returns a render array that will be rendered by AjaxRenderer.
+   *
+   * Verifies that the response incorporates JavaScript settings generated
+   * during the page request by adding a dummy setting.
+   */
+  public function render() {
+    return [
+      '#attached' => [
+        'library' => [
+          'core/drupalSettings',
+        ],
+        'drupalSettings' => [
+          'ajax' => 'test',
+        ],
+      ],
+    ];
+  }
+
+  /**
+   * Returns the used theme.
+   */
+  public function theme() {
+    return [
+      '#markup' => 'Current theme: ' . \Drupal::theme()->getActiveTheme()->getName(),
+    ];
+  }
+
+  /**
+   * Returns an AjaxResponse; settings command set last.
+   *
+   * Helps verifying AjaxResponse reorders commands to ensure correct execution.
+   */
+  public function order() {
+    $response = new AjaxResponse();
+    // HTML insertion command.
+    $response->addCommand(new HtmlCommand('body', 'Hello, world!'));
+    $build['#attached']['library'][] = 'ajax_test/order';
+    $response->setAttachments($build['#attached']);
+
+    return $response;
+  }
+
+  /**
+   * Returns an AjaxResponse with alert command.
+   *
+   * @param \Symfony\Component\HttpFoundation\Request $request
+   *   The current request object.
+   *
+   * @return \Drupal\Core\Ajax\AjaxResponse
+   *   The JSON response object.
+   */
+  public function renderError(Request $request) {
+    $message = '';
+    $query = $request->query;
+    if ($query->has('message')) {
+      $message = $query->get('message');
+    }
+    $response = new AjaxResponse();
+    $response->addCommand(new AlertCommand($message));
+    return $response;
+  }
+
+  /**
+   * Returns a render array of form elements and links for dialog.
+   */
+  public function dialog() {
+    // Add two wrapper elements for testing non-modal dialogs. Modal dialogs use
+    // the global drupal-modal wrapper by default.
+    $build['dialog_wrappers'] = ['#markup' => '<div id="ajax-test-dialog-wrapper-1"></div><div id="ajax-test-dialog-wrapper-2"></div>'];
+
+    // Dialog behavior applied to a button.
+    $build['form'] = \Drupal::formBuilder()->getForm('Drupal\ajax_test\Form\AjaxTestDialogForm');
+
+    // Dialog behavior applied to a #type => 'link'.
+    $build['link'] = [
+      '#type' => 'link',
+      '#title' => 'Link 1 (modal)',
+      '#url' => Url::fromRoute('ajax_test.dialog_contents'),
+      '#attributes' => [
+        'class' => ['use-ajax'],
+        'data-dialog-type' => 'modal',
+      ],
+    ];
+
+    // Dialog behavior applied to links rendered by links.html.twig.
+    $build['links'] = [
+      '#theme' => 'links',
+      '#links' => [
+        'link2' => [
+          'title' => 'Link 2 (modal)',
+          'url' => Url::fromRoute('ajax_test.dialog_contents'),
+          'attributes' => [
+            'class' => ['use-ajax'],
+            'data-dialog-type' => 'modal',
+            'data-dialog-options' => json_encode([
+              'width' => 400,
+            ]),
+          ],
+        ],
+        'link3' => [
+          'title' => 'Link 3 (non-modal)',
+          'url' => Url::fromRoute('ajax_test.dialog_contents'),
+          'attributes' => [
+            'class' => ['use-ajax'],
+            'data-dialog-type' => 'dialog',
+            'data-dialog-options' => json_encode([
+              'target' => 'ajax-test-dialog-wrapper-1',
+              'width' => 800,
+            ]),
+          ],
+        ],
+        'link4' => [
+          'title' => 'Link 4 (close non-modal if open)',
+          'url' => Url::fromRoute('ajax_test.dialog_close'),
+          'attributes' => [
+            'class' => ['use-ajax'],
+            'data-dialog-type' => 'modal',
+          ],
+        ],
+        'link5' => [
+          'title' => 'Link 5 (form)',
+          'url' => Url::fromRoute('ajax_test.dialog_form'),
+          'attributes' => [
+            'class' => ['use-ajax'],
+            'data-dialog-type' => 'modal',
+          ],
+        ],
+        'link6' => [
+          'title' => 'Link 6 (entity form)',
+          'url' => Url::fromRoute('contact.form_add'),
+          'attributes' => [
+            'class' => ['use-ajax'],
+            'data-dialog-type' => 'modal',
+            'data-dialog-options' => json_encode([
+              'width' => 800,
+              'height' => 500,
+            ]),
+          ],
+        ],
+        'link7' => [
+          'title' => 'Link 7 (non-modal, no target)',
+          'url' => Url::fromRoute('ajax_test.dialog_contents'),
+          'attributes' => [
+            'class' => ['use-ajax'],
+            'data-dialog-type' => 'dialog',
+            'data-dialog-options' => json_encode([
+              'width' => 800,
+            ]),
+          ],
+        ],
+        'link8' => [
+          'title' => 'Link 8 (ajax)',
+          'url' => Url::fromRoute('ajax_test.admin.theme'),
+          'attributes' => [
+            'class' => ['use-ajax'],
+            'data-dialog-type' => 'modal',
+            'data-dialog-options' => json_encode([
+              'width' => 400,
+            ]),
+          ],
+        ],
+      ],
+    ];
+
+    return $build;
+  }
+
+  /**
+   * Returns an AjaxResponse with command to close dialog.
+   *
+   * @return \Drupal\Core\Ajax\AjaxResponse
+   *   The JSON response object.
+   */
+  public function dialogClose() {
+    $response = new AjaxResponse();
+    $response->addCommand(new CloseDialogCommand('#ajax-test-dialog-wrapper-1'));
+    return $response;
+  }
+
+  /**
+   * Render types.
+   *
+   * @return array
+   *   Render types.
+   */
+  protected function getRenderTypes() {
+    $render_single_root = [
+      'pre-wrapped-div' => '<div class="pre-wrapped">pre-wrapped<script> var test;</script></div>',
+      'pre-wrapped-span' => '<span class="pre-wrapped">pre-wrapped<script> var test;</script></span>',
+      'pre-wrapped-whitespace' => ' <div class="pre-wrapped-whitespace">pre-wrapped-whitespace</div>' . "\r\n",
+      'not-wrapped' => 'not-wrapped',
+      'comment-string-not-wrapped' => '<!-- COMMENT -->comment-string-not-wrapped',
+      'comment-not-wrapped' => '<!-- COMMENT --><div class="comment-not-wrapped">comment-not-wrapped</div>',
+      'svg' => '<svg xmlns="http://www.w3.org/2000/svg" width="10" height="10"><rect x="0" y="0" height="10" width="10" fill="green"></rect></svg>',
+      'empty' => '',
+    ];
+    $render_multiple_root = [
+      'mixed' => ' foo <!-- COMMENT -->  foo bar<div class="a class"><p>some string</p></div> additional not wrapped strings, <!-- ANOTHER COMMENT --> <p>final string</p>',
+      'top-level-only' => '<div>element #1</div><div>element #2</div>',
+      'top-level-only-pre-whitespace' => ' <div>element #1</div><div>element #2</div> ',
+      'top-level-only-middle-whitespace-span' => '<span>element #1</span> <span>element #2</span>',
+      'top-level-only-middle-whitespace-div' => '<div>element #1</div> <div>element #2</div>',
+    ];
+
+    $render_info = [];
+    foreach ($render_single_root as $key => $render) {
+      $render_info[$key] = ['render' => $render, 'effect' => 'fade'];
+    }
+    foreach ($render_multiple_root as $key => $render) {
+      $render_info[$key] = ['render' => $render, 'effect' => 'none'];
+      $render_info["$key--effect"] = ['render' => $render, 'effect' => 'fade'];
+    }
+
+    return $render_info;
+  }
+
+  /**
+   * Returns a page from which to test Ajax global events.
+   *
+   * @return array
+   *   The render array.
+   */
+  public function globalEvents() {
+    return [
+      '#attached' => [
+        'library' => [
+          'ajax_test/global_events',
+        ],
+      ],
+      '#markup' => implode('', [
+        '<div id="test_global_events_log"></div>',
+        '<a id="test_global_events_drupal_ajax_link" class="use-ajax" href="' . Url::fromRoute('ajax_test.global_events_clear_log')->toString() . '">Drupal Ajax</a>',
+        '<div id="test_global_events_log2"></div>',
+      ]),
+    ];
+  }
+
+  /**
+   * Returns an AjaxResponse with command to clear the 'test_global_events_log'.
+   *
+   * @return \Drupal\Core\Ajax\AjaxResponse
+   *   The JSON response object.
+   */
+  public function globalEventsClearLog() {
+    $response = new AjaxResponse();
+    $response->addCommand(new HtmlCommand('#test_global_events_log', ''));
+    return $response;
+  }
+
+  /**
+   * Callback to provide an exception via Ajax.
+   *
+   * @throws \Exception
+   *   The expected exception.
+   */
+  public function throwException() {
+    throw new \Exception('This is an exception.');
+  }
+
+  /**
+   * Provides an Ajax link for the exception.
+   *
+   * @return array
+   *   The Ajax link.
+   */
+  public function exceptionLink() {
+    return [
+      '#type' => 'link',
+      '#url' => Url::fromRoute('ajax_test.throw_exception'),
+      '#title' => 'Ajax Exception',
+      '#attributes' => [
+        'class' => ['use-ajax'],
+      ],
+      '#attached' => [
+        'library' => [
+          'core/drupal.ajax',
+        ],
+      ],
+    ];
+  }
+
+  /**
+   * Provides an Ajax link used with different HTTP methods.
+   *
+   * @return array
+   *   The AJAX link.
+   */
+  public function httpMethods(): array {
+    return [
+      '#type' => 'link',
+      '#title' => 'Link',
+      '#url' => Url::fromRoute('ajax_test.http_methods.dialog'),
+      '#attributes' => [
+        'class' => ['use-ajax'],
+        'data-dialog-type' => 'modal',
+        'data-dialog-options' => Json::encode(['width' => 800]),
+        // Use this state var to change the HTTP method in tests.
+        // @see \Drupal\FunctionalJavascriptTests\Ajax\DialogTest::testHttpMethod()
+        'data-ajax-http-method' => \Drupal::state()->get('ajax_test.http_method', 'POST'),
+      ],
+      '#attached' => [
+        'library' => [
+          'core/drupal.dialog.ajax',
+        ],
+      ],
+    ];
+  }
+
+  /**
+   * Provides a modal dialog to test links with different HTTP methods.
+   *
+   * @return array
+   *   The render array.
+   */
+  public function httpMethodsDialog(): array {
+    return ['#markup' => 'Modal dialog contents'];
+  }
+
+}

core/modules/system/tests/modules/ajax_test/src/Form/AjaxTestDialogForm.php

@@ -0,0 +1,130 @@
+<?php
+
+namespace Drupal\ajax_test\Form;
+
+use Drupal\ajax_test\Controller\AjaxTestController;
+use Drupal\Core\Form\FormBase;
+use Drupal\Core\Ajax\AjaxResponse;
+use Drupal\Core\Ajax\OpenDialogCommand;
+use Drupal\Core\Ajax\OpenModalDialogCommand;
+use Drupal\Core\Ajax\OpenModalDialogWithUrl;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Url;
+
+/**
+ * Dummy form for testing DialogRenderer with _form routes.
+ *
+ * @internal
+ */
+class AjaxTestDialogForm extends FormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'ajax_test_dialog_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+    $form['button1'] = [
+      '#type' => 'submit',
+      '#name' => 'button1',
+      '#value' => 'Button 1 (modal)',
+      '#ajax' => [
+        'callback' => '::modal',
+      ],
+    ];
+    $form['button2'] = [
+      '#type' => 'submit',
+      '#name' => 'button2',
+      '#value' => 'Button 2 (non-modal)',
+      '#ajax' => [
+        'callback' => '::nonModal',
+      ],
+    ];
+    $form['button3'] = [
+      '#type' => 'submit',
+      '#name' => 'button3',
+      '#value' => 'Button 3 (modal from url)',
+      '#ajax' => [
+        'callback' => '::modalFromUrl',
+      ],
+    ];
+
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validateForm(array &$form, FormStateInterface $form_state) {
+
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {
+    $form_state->setRedirect('ajax_test.dialog_contents');
+  }
+
+  /**
+   * AJAX callback handler for AjaxTestDialogForm.
+   */
+  public function modal(&$form, FormStateInterface $form_state) {
+    return $this->dialog(TRUE);
+  }
+
+  /**
+   * AJAX callback handler for Url modal, AjaxTestDialogForm.
+   */
+  public function modalFromUrl(&$form, FormStateInterface $form_state) {
+    return $this->dialog(TRUE, TRUE);
+  }
+
+  /**
+   * AJAX callback handler for AjaxTestDialogForm.
+   */
+  public function nonModal(&$form, FormStateInterface $form_state) {
+    return $this->dialog(FALSE);
+  }
+
+  /**
+   * Util to render dialog in ajax callback.
+   *
+   * @param bool $is_modal
+   *   (optional) TRUE if modal, FALSE if plain dialog. Defaults to FALSE.
+   * @param bool $is_url
+   *   (optional) True if modal is from a URL, Defaults to FALSE.
+   *
+   * @return \Drupal\Core\Ajax\AjaxResponse
+   *   An ajax response object.
+   */
+  protected function dialog(bool $is_modal = FALSE, bool $is_url = FALSE) {
+    $content = AjaxTestController::dialogContents();
+    $response = new AjaxResponse();
+    $title = $this->t('AJAX Dialog & contents');
+
+    // Attach the library necessary for using the Open(Modal)DialogCommand and
+    // set the attachments for this Ajax response.
+    $content['#attached']['library'][] = 'core/drupal.dialog.ajax';
+
+    if ($is_modal) {
+      if ($is_url) {
+        $response->addCommand(new OpenModalDialogWithUrl(Url::fromRoute('ajax_test.dialog_form')->toString(), []));
+      }
+      else {
+        $response->addCommand(new OpenModalDialogCommand($title, $content));
+      }
+    }
+    else {
+      $selector = '#ajax-test-dialog-wrapper-1';
+      $response->addCommand(new OpenDialogCommand($selector, $title, $content));
+    }
+    return $response;
+  }
+
+}

core/modules/system/tests/modules/ajax_test/src/Form/AjaxTestFocusFirstForm.php

@@ -0,0 +1,228 @@
+<?php
+
+namespace Drupal\ajax_test\Form;
+
+use Drupal\Core\Ajax\AjaxResponse;
+use Drupal\Core\Ajax\FocusFirstCommand;
+use Drupal\Core\Form\FormInterface;
+use Drupal\Core\Form\FormStateInterface;
+
+/**
+ * Form for testing AJAX FocusFirstCommand.
+ *
+ * @internal
+ */
+class AjaxTestFocusFirstForm implements FormInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'ajax_test_focus_first_command_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+    $form['first_input'] = [
+      '#type' => 'textfield',
+    ];
+    $form['second_input'] = [
+      '#type' => 'textfield',
+    ];
+    $form['a_container'] = [
+      '#type' => 'container',
+      '#attributes' => [
+        'id' => 'a-container',
+      ],
+    ];
+    $form['a_container']['first_container_input'] = [
+      '#type' => 'textfield',
+    ];
+    $form['a_container']['second_container_input'] = [
+      '#type' => 'textfield',
+    ];
+    $form['focusable_container_without_tabbable_children'] = [
+      '#type' => 'container',
+      '#attributes' => [
+        'tabindex' => '-1',
+        'id' => 'focusable-container-without-tabbable-children',
+      ],
+      '#markup' => 'No tabbable children here',
+    ];
+
+    $form['multiple_of_same_selector_1'] = [
+      '#type' => 'container',
+      '#attributes' => [
+        'id' => 'multiple-of-same-selector-1',
+        'class' => ['multiple-of-same-selector'],
+      ],
+    ];
+
+    $form['multiple_of_same_selector_1']['inside_same_selector_container_1'] = [
+      '#type' => 'textfield',
+    ];
+
+    $form['multiple_of_same_selector_2'] = [
+      '#type' => 'container',
+      '#attributes' => [
+        'id' => 'multiple-of-same-selector-2',
+        'class' => ['multiple-of-same-selector'],
+      ],
+    ];
+
+    $form['multiple_of_same_selector_2']['inside_same_selector_container_2'] = [
+      '#type' => 'textfield',
+    ];
+
+    $form['nothing_tabbable'] = [
+      '#type' => 'container',
+      '#attributes' => [
+        'id' => 'nothing-tabbable',
+      ],
+      '#markup' => 'nothing tabbable',
+    ];
+
+    $form['nothing_tabbable']['nested'] = [
+      '#type' => 'container',
+      '#markup' => 'There are divs in here, but nothing tabbable',
+    ];
+
+    $form['focus_first_in_container'] = [
+      '#type' => 'submit',
+      '#value' => 'Focus the first item in a container',
+      '#name' => 'focusFirstContainer',
+      '#ajax' => [
+        'callback' => '::focusFirstInContainer',
+      ],
+    ];
+    $form['focus_first_in_form'] = [
+      '#type' => 'submit',
+      '#value' => 'Focus the first item in the form',
+      '#name' => 'focusFirstForm',
+      '#ajax' => [
+        'callback' => '::focusFirstInForm',
+      ],
+    ];
+    $form['uses_selector_with_multiple_matches'] = [
+      '#type' => 'submit',
+      '#value' => 'Uses selector with multiple matches',
+      '#name' => 'SelectorMultipleMatches',
+      '#ajax' => [
+        'callback' => '::focusFirstSelectorMultipleMatch',
+      ],
+    ];
+    $form['focusable_container_no_tabbable_children'] = [
+      '#type' => 'submit',
+      '#value' => 'Focusable container, no tabbable children',
+      '#name' => 'focusableContainerNotTabbableChildren',
+      '#ajax' => [
+        'callback' => '::focusableContainerNotTabbableChildren',
+      ],
+    ];
+
+    $form['selector_has_nothing_tabbable'] = [
+      '#type' => 'submit',
+      '#value' => 'Try to focus container with nothing tabbable',
+      '#name' => 'SelectorNothingTabbable',
+      '#ajax' => [
+        'callback' => '::selectorHasNothingTabbable',
+      ],
+    ];
+
+    $form['selector_does_not_exist'] = [
+      '#type' => 'submit',
+      '#value' => 'Call FocusFirst on selector that does not exist.',
+      '#name' => 'SelectorNotExist',
+      '#ajax' => [
+        'callback' => '::selectorDoesNotExist',
+      ],
+    ];
+
+    $form['#attached']['library'][] = 'ajax_test/focus.first';
+
+    return $form;
+  }
+
+  /**
+   * Callback for testing FocusFirstCommand on a container.
+   *
+   * @return \Drupal\Core\Ajax\AjaxResponse
+   *   The AJAX response.
+   */
+  public function selectorDoesNotExist() {
+    $response = new AjaxResponse();
+    return $response->addCommand(new FocusFirstCommand('#selector-does-not-exist'));
+  }
+
+  /**
+   * Callback for testing FocusFirstCommand on a container.
+   *
+   * @return \Drupal\Core\Ajax\AjaxResponse
+   *   The AJAX response.
+   */
+  public function selectorHasNothingTabbable() {
+    $response = new AjaxResponse();
+    return $response->addCommand(new FocusFirstCommand('#nothing-tabbable'));
+  }
+
+  /**
+   * Callback for testing FocusFirstCommand on a container.
+   *
+   * @return \Drupal\Core\Ajax\AjaxResponse
+   *   The AJAX response.
+   */
+  public function focusableContainerNotTabbableChildren() {
+    $response = new AjaxResponse();
+    return $response->addCommand(new FocusFirstCommand('#focusable-container-without-tabbable-children'));
+  }
+
+  /**
+   * Callback for testing FocusFirstCommand on a container.
+   *
+   * @return \Drupal\Core\Ajax\AjaxResponse
+   *   The AJAX response.
+   */
+  public function focusFirstSelectorMultipleMatch() {
+    $response = new AjaxResponse();
+    return $response->addCommand(new FocusFirstCommand('.multiple-of-same-selector'));
+  }
+
+  /**
+   * Callback for testing FocusFirstCommand on a container.
+   *
+   * @return \Drupal\Core\Ajax\AjaxResponse
+   *   The AJAX response.
+   */
+  public function focusFirstInContainer() {
+    $response = new AjaxResponse();
+    return $response->addCommand(new FocusFirstCommand('#a-container'));
+  }
+
+  /**
+   * Callback for testing FocusFirstCommand on a form.
+   *
+   * @return \Drupal\Core\Ajax\AjaxResponse
+   *   The AJAX response.
+   */
+  public function focusFirstInForm() {
+    $response = new AjaxResponse();
+    return $response->addCommand(new FocusFirstCommand('#ajax-test-focus-first-command-form'));
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validateForm(array &$form, FormStateInterface $form_state) {
+
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {
+
+  }
+
+}

core/modules/system/tests/modules/ajax_test/src/Form/AjaxTestForm.php

@@ -0,0 +1,92 @@
+<?php
+
+namespace Drupal\ajax_test\Form;
+
+use Drupal\Core\Ajax\AjaxResponse;
+use Drupal\Core\Ajax\MessageCommand;
+use Drupal\Core\Url;
+use Drupal\Core\Form\FormBase;
+use Drupal\Core\Form\FormStateInterface;
+
+/**
+ * Dummy form for testing DialogRenderer with _form routes.
+ *
+ * @internal
+ */
+class AjaxTestForm extends FormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'ajax_test_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+
+    $form['#action'] = Url::fromRoute('ajax_test.dialog')->toString();
+
+    $form['description'] = [
+      '#markup' => '<p>' . $this->t("Ajax Form contents description.") . '</p>',
+    ];
+
+    $form['actions'] = [
+      '#type' => 'actions',
+    ];
+    $form['actions']['submit'] = [
+      '#type' => 'submit',
+      '#value' => $this->t('Do it'),
+    ];
+    $form['actions']['preview'] = [
+      '#title' => 'Preview',
+      '#type' => 'link',
+      '#url' => Url::fromRoute('ajax_test.dialog_form'),
+      '#attributes' => [
+        'class' => ['use-ajax', 'button'],
+        'data-dialog-type' => 'modal',
+      ],
+    ];
+    $form['actions']['hello_world'] = [
+      '#type' => 'submit',
+      '#value' => $this->t('Hello world'),
+      // No regular submit-handler. This form only works via JavaScript.
+      '#submit' => [],
+      '#ajax' => [
+        'callback' => '::helloWorld',
+        'event' => 'click',
+      ],
+    ];
+    return $form;
+  }
+
+  /**
+   * An AJAX callback that prints "Hello World!" as a message.
+   *
+   * @param array $form
+   *   The form array to remove elements from.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
+   *
+   * @return \Drupal\Core\Ajax\AjaxResponse
+   *   An AJAX response.
+   */
+  public function helloWorld(array &$form, FormStateInterface $form_state) {
+    $response = new AjaxResponse();
+    $response->addCommand(new MessageCommand('Hello world!'));
+    return $response;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {}
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validateForm(array &$form, FormStateInterface $form_state) {}
+
+}