first commit

core/tests/Drupal/Tests/StreamCapturer.php

@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests;
+
+/**
+ * Captures output to a stream and stores it for retrieval.
+ */
+class StreamCapturer extends \php_user_filter {
+
+  public static $cache = '';
+
+  #[\ReturnTypeWillChange]
+  public function filter($in, $out, &$consumed, $closing) {
+    while ($bucket = stream_bucket_make_writeable($in)) {
+      self::$cache .= $bucket->data;
+      // cSpell:disable-next-line
+      $consumed += $bucket->datalen;
+      stream_bucket_append($out, $bucket);
+    }
+    // cSpell:disable-next-line
+    return PSFS_FEED_ME;
+  }
+
+}