Fatal error: Uncaught Error: Class "PHPUnit\Framework\TestCase" not found in /var/www/magento/html/app/code/Amasty/Rules/Test/Unit/Model/Rule/Action/Discount/SetofFixedTest.php:23 Stack trace: #0 {main} thrown in /var/www/magento/html/app/code/Amasty/Rules/Test/Unit/Model/Rule/Action/Discount/SetofFixedTest.php on line 23