Fatal error: Uncaught Error: Class "PHPUnit\Framework\TestCase" not found in C:\xampp\htdocs\r10ca\vendor\phar-io\manifest\tests\xml\ExtElementCollectionTest.php:6 Stack trace: #0 {main} thrown in C:\xampp\htdocs\r10ca\vendor\phar-io\manifest\tests\xml\ExtElementCollectionTest.php on line 6