Here's how it usually plays out: the developer thinks, "I need to do unit tests, and I should use PHPUnit because it's a standard. I don't know much about it, though." Then he visits the PHPUnit site and reads the first chapter of the documentation, then the second, then the third… and is left scratching his head.

[...] Maybe something similar happened to you. Maybe not. But you really should know what to test and how to test it. Such knowledge comes from experience, so in this article I'll share some of my experience with unit testing.

The article's not so much an introduction to unit testing as it is some of the experiences he's had around testing his applications both at the code level and from a functional perspective. He also mentions some alternatives to the standard PHPUnit testing like Atoum and EnhancePHP.