Fatal error: Uncaught Error: Class "Drupal\Tests\user\Unit\Plugin\Action\RoleUserTestBase" not found in /home/www/drupal8/test/core/modules/user/tests/src/Unit/Plugin/Action/RemoveRoleUserTest.php:11
Stack trace:
#0 {main}
thrown in /home/www/drupal8/test/core/modules/user/tests/src/Unit/Plugin/Action/RemoveRoleUserTest.php on line 11