Fatal error: Uncaught Error: Class 'Drupal\Tests\flag\Kernel\FlagKernelTestBase' not found in /var/www/html/tmp/contrib/flag/tests/src/Kernel/AccessTest.php:18 Stack trace: #0 {main} thrown in /var/www/html/tmp/contrib/flag/tests/src/Kernel/AccessTest.php on line 18