My first goal for the WordPress Editorial Calendar was to make it do anything useful. I was new to JavaScript and PHP and didn't really know what I could pull off. In a few days I had a proof of concept. In a few more I had a working version and was asking friends to install it. The calendar worked...sort of. I spent three times as much time fixing bugs as I did coding. Once the plugin worked, I wrote unit tests to make sure it kept working.

He introduces the QUnit testing tool and includes some sample tests showing you how to create both a pass/fail and how to test a PHP value passed out to the page via PHP. There's also a section on getting WordPress and QUnit integrated and only executing when there's a "qunit" parameter on the URL. Actual tests for his calendar plugin are included and you can see the results of the tests here.