Fatal error: Uncaught Error: Class "PHPUnit\Framework\TestCase" not found in C:\xampp\htdocs\BK\bateriasec\vendor\sebastian\environment\tests\OperatingSystemTest.php:17 Stack trace: #0 {main} thrown in C:\xampp\htdocs\BK\bateriasec\vendor\sebastian\environment\tests\OperatingSystemTest.php on line 17