On the Debuggable blog, Tim Koschutki has posted the first part of a series looking at unit testing the CakePHP framework. This first article introduces you to the idea of unit testing to help lay the foundation for what's to come.

So you want to read up on Unit Testing in CakePHP? That is great, testing can be such a help in finding bugs. [...] Surprisingly, many people do not know yet what unit testing is. In this first part of a whole series you can get a good grasp of what it is and is not.

He goes over the basic concepts behind the testing - setting up test cases, comparing results, automating them and how they related to code coverage. He gets into more detail with a list of the assert functions (like assertNotEqual or assertClone) and some examples using the simpletest unit testing software. He wraps it up by listing some of the benefits of unit testing, the limitations of it, TDD and what Mock objects are.