Fatal error: Uncaught Error: Class "Drupal\KernelTests\KernelTestBase" not found in /home/qcsvlel/www/core/modules/migrate/tests/src/Kernel/MigrateMissingDatabaseTest.php:18 Stack trace: #0 {main} thrown in /home/qcsvlel/www/core/modules/migrate/tests/src/Kernel/MigrateMissingDatabaseTest.php on line 18