Fatal error: Uncaught Error: Class "Drupal\Core\Plugin\Context\ContextDefinition" not found in /home/www/drupal8/test/core/tests/Drupal/Tests/Core/Plugin/Fixtures/InheritedContextDefinition.php:12 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/tests/Drupal/Tests/Core/Plugin/Fixtures/InheritedContextDefinition.php on line 12