Behat is an open source behavior driven development framework for php 5.3.

Behat was inspired by Ruby's Cucumber project and especially it's syntax part (Gherkin). It tries to be like Cucumber with input (Feature files) and output (console formatters), but in core, it built from the ground on the shoulders of giants:

Symfony Dependency Injection component Symfony Event Dispatcher component Symfony Console component Symfony Finder component Unlike any other php testing framework that tests applications inside out. Behat is testing applications outside in. It means, that Behat works only with your application's input/output. If you want to test your models - use unit testing framework instead, Behat created for behavior testing (but can be used for anything +) ).

Also, there's symfony plugin for Behat, so you can start testing your applications right now.