Fatal error: Uncaught Error: Class "Drupal\Tests\comment\Functional\CommentTestBase" not found in /home/www/drupal8/test/core/modules/rdf/tests/src/Functional/CommentAttributesTest.php:16 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/rdf/tests/src/Functional/CommentAttributesTest.php on line 16