Automated testing is big news these days. There's hardly a PHP conference happening without a talk on testing automation or derivative methodologies. TDD (Test-Driven Development) and BDD (Behaviour Driven Development) are all around us. So why should you care about all this? [...] The more complex an application becomes, the harder it is to be sure that each new feature or bug fix won't break the system, and that decreases your overall confidence in your work as developer. That's exactly the reason why you need automated testing - to be confident that you're not breaking important parts of an application.
For his examples he uses a simple Silex-based application (found here on github) that just shows a main page and an "add article" page that returns a preview when submitted. He shows how to get Behat/Mink installed and how to bootstrap PHPUnit to allow you to execute your tests. Also included is a sample test that clicks the "Add Article" link, runs a few checks and fills in some data. The form is submitted and the "preview" page is checked for valid results.