Fatal error: Uncaught Error: Class 'Drupal\KernelTests\Core\Entity\EntityKernelTestBase' not found in /var/www/html/tmp/contrib/entity/tests/src/Kernel/BundleEntityDuplicatorTest.php:18 Stack trace: #0 {main} thrown in /var/www/html/tmp/contrib/entity/tests/src/Kernel/BundleEntityDuplicatorTest.php on line 18