Fatal error: Uncaught Error: Class "Drupal\Tests\comment\Functional\CommentTestBase" not found in /home/www/drupal8/test/core/modules/comment/tests/src/Functional/CommentBlockTest.php:13
Stack trace:
#0 {main}
thrown in /home/www/drupal8/test/core/modules/comment/tests/src/Functional/CommentBlockTest.php on line 13