Fatal error: Uncaught Error: Class "Drupal\Tests\migrate\Kernel\MigrateTestBase" not found in /home/www/drupal8/test/modules/migrate_plus/tests/src/Kernel/MigrateTableTest.php:14 Stack trace: #0 {main} thrown in /home/www/drupal8/test/modules/migrate_plus/tests/src/Kernel/MigrateTableTest.php on line 14