Fatal error: Uncaught Error: Class "Drupal\Tests\migrate\Unit\MigrateTestCase" not found in /home/www/drupal8/test/core/modules/migrate/tests/src/Unit/MigrateSqlSourceTestCase.php:17 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/migrate/tests/src/Unit/MigrateSqlSourceTestCase.php on line 17