Fatal error: Uncaught Error: Class "Drupal\Tests\layout_builder\Kernel\LayoutBuilderCompatibilityTestBase" not found in /home/www/drupal8/test/core/modules/layout_builder/tests/src/Kernel/LayoutBuilderInstallTest.php:15 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/layout_builder/tests/src/Kernel/LayoutBuilderInstallTest.php on line 15