Fatal error: Uncaught Error: Class "Drupal\Tests\media\FunctionalJavascript\MediaJavascriptTestBase" not found in /home/www/drupal8/test/core/modules/media/tests/src/FunctionalJavascript/MediaUiJavascriptTest.php:15 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/media/tests/src/FunctionalJavascript/MediaUiJavascriptTest.php on line 15