Fatal error: Uncaught Error: Class 'PHPUnit\Framework\TestCase' not found in /home/esecureh/public_html/magdemo/vendor/magento/module-downloadable/Test/Unit/Controller/Adminhtml/Downloadable/Product/Edit/LinkTest.php:20 Stack trace: #0 {main} thrown in /home/esecureh/public_html/magdemo/vendor/magento/module-downloadable/Test/Unit/Controller/Adminhtml/Downloadable/Product/Edit/LinkTest.php on line 20