Fatal error: Uncaught Error: Class 'PHPUnit\Framework\TestCase' not found in /home/esecureh/public_html/magdemo/vendor/magento/module-configurable-product/Test/Unit/Block/Product/Configurable/AttributeSelectorTest.php:16 Stack trace: #0 {main} thrown in /home/esecureh/public_html/magdemo/vendor/magento/module-configurable-product/Test/Unit/Block/Product/Configurable/AttributeSelectorTest.php on line 16