Fatal error: Uncaught Error: Class "Drupal\Tests\aggregator\Functional\Rest\ItemResourceTestBase" not found in /home/www/drupal8/test/core/modules/aggregator/tests/src/Functional/Rest/ItemXmlBasicAuthTest.php:11 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/aggregator/tests/src/Functional/Rest/ItemXmlBasicAuthTest.php on line 11