Fatal error: Uncaught Error: Class "Drupal\content_translation\Tests\ContentTranslationTestBase" not found in /home/www/drupal8/test/core/modules/content_translation/src/Tests/ContentTranslationUITestBase.php:21 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/content_translation/src/Tests/ContentTranslationUITestBase.php on line 21