Fatal error: Uncaught Error: Class "PHPUnit\Framework\TestCase" not found in /opt/lampp/htdocs/tsiasset/vendor/phpoffice/math/tests/Math/Reader/MathMLTest.php:15 Stack trace: #0 {main} thrown in /opt/lampp/htdocs/tsiasset/vendor/phpoffice/math/tests/Math/Reader/MathMLTest.php on line 15