Fatal error: Uncaught Error: Class "Drupal\Tests\rest\Functional\ResourceTestBase" not found in /home/qcsvlel/www/core/modules/user/tests/src/Functional/UserRegistrationRestTest.php:21 Stack trace: #0 {main} thrown in /home/qcsvlel/www/core/modules/user/tests/src/Functional/UserRegistrationRestTest.php on line 21