Fatal error: Uncaught Error: Class "Drupal\KernelTests\Core\Entity\EntityKernelTestBase" not found in /home/qcsvlel/www/core/tests/Drupal/KernelTests/Core/Field/FieldItemTest.php:18 Stack trace: #0 {main} thrown in /home/qcsvlel/www/core/tests/Drupal/KernelTests/Core/Field/FieldItemTest.php on line 18