I was recently working on a command line PHP tool, and didn't have easy access to our normal PHP unit testing framework built around SimpleTest. [...] I didn't need support for mock objects or complicated assertions - just a bare basic assertTrue() would do the trick.

He includes the code (of course) and an example of it in action, three tests with their assertions. It's a simple little tool made of a simple purpose, a starting place for developers just learning unit testing to learn from.