Various testing tools exist to test the different aspects and layers of PHP applications. There is PHPUnit for Unit Testing (and Test-Driven Development), Behat and PHPSpec for Acceptance Testing (and Behaviour-Driven Development), Selenium for System Testing, and a plethora of tools for testing non-functional aspects such as performance and security.

His presentation provides an overview of the goals of each of these tools and shows the first steps to using them in your daily routine

https://www.youtube.com/watch?v=ebn_gvVPX0E