Fatal error: Uncaught Error: Class "PHPUnit\Framework\TestCase" not found in /home/airtimer/public_html/vendor/magento/module-inventory-grouped-product/Test/Integration/Order/PlaceOrderOnCustomStockTest.php:21 Stack trace: #0 {main} thrown in /home/airtimer/public_html/vendor/magento/module-inventory-grouped-product/Test/Integration/Order/PlaceOrderOnCustomStockTest.php on line 21