PHPUnit is a unit testing software framework for PHP. It provides both a framework that makes writing unit tests easy as well as the functionality to easily run the tests and analyze their results. This video shows you how to build a relatively simple class, using TDD techniques. It also discusses various PHPUnit methods and explains how to create mock objects.
Video source: http://net.tutsplus.com/tutorials/php/hands-on-unit-testing-with-phpunit/