Unit testing suite for PHP5 Unit testing allows you to write small test methods which verify units of functionality in your program. It is a powerful technique for improving the quality of your software, preventing regressions, and allowing confident refactoring of your code. PHPUnit is a unit testing suite for the PHP language, modelled on the xUnit testing framework, designed by Kent Beck and Erich Gamma. If you've used JUnit (for Java), PyUnit (for Python), CxxUnit (for C++), or any of the other equivalents for other languages, the API for this package should seem fairly familiar. If you've never written unit tests before, the PHPUnit API is simple to learn and use.