Cannot find PHPUnit in include path phpstorm

Question

Cannot find PHPUnit in include path is the error message I get when I try to run my code in phpstorm.

In the PHP Settings, my PHP level language is 5

Answer 1

I had this problem after adding PHPUnit via composer.

I fixed this by choosing use custom autoloader in Settings -> Languages and Frameworks -> PHP -> PHPUnit, then adding /vendor/autoload.php as the location of the custom autoloader.