Fatal error: Uncaught Error: Class "PHPUnit\Framework\TestCase" not found in /var/www/html/core/vendor/sendgrid/php-http-client/test/unit/FilesExistTest.php:7 Stack trace: #0 {main} thrown in /var/www/html/core/vendor/sendgrid/php-http-client/test/unit/FilesExistTest.php on line 7