Fatal error: Uncaught Error: Class "Drupal\Tests\migrate_drupal\Kernel\d6\MigrateDrupal6TestBase" not found in /home/qcsvlel/www/core/modules/migrate_drupal/tests/src/Kernel/d6/FieldDiscoveryTest.php:21 Stack trace: #0 {main} thrown in /home/qcsvlel/www/core/modules/migrate_drupal/tests/src/Kernel/d6/FieldDiscoveryTest.php on line 21