Fatal error: Uncaught Error: Class "PHPUnit\Framework\TestCase" not found in C:\xampp\htdocs\r10csm\vendor\symfony\var-dumper\Tests\Caster\FiberCasterTest.php:17 Stack trace: #0 {main} thrown in C:\xampp\htdocs\r10csm\vendor\symfony\var-dumper\Tests\Caster\FiberCasterTest.php on line 17