Posted on July 18, 2010
MediaWiki testing with PHPUnit
I figured having some unit tests for Maps, the MediaWiki extension to work with geographical data and display it by embedding dynamic maps into your articles, would be beneficial to it’s quality. It’s pretty hard to try cover all possible use cases with manual tests, and consumes a lot of time in any case. I therefore decided to try create some tests for the coordinate parser and formatter class, as it’s arguably the core feature of Maps.
I started off by trying to install plain PHPUnit, which is the most commonly used unit testing framework for PHP. This took me a while, as you are supposed to install it using PEAR (PHP Extension and Application Repository), a repository tool for PHP applications, and has never used this before. After two hours or so of messing around, I got both installed 🙂 Then I went on investigating how I could best integrate this into my work-flow, and discovered that PHPUnit comes bundled with Zend Studio, seamlessly integrated, working completely out of the box o_O.
I then wrote a test case for the coordinate parsing and formatting class of Maps. I had a hard time getting it to work, as I needed to include MW itself, as the class uses MW functions. After some non-constructive discussion with several fellow MW devs I found a way to get it to work by including the maintenance script entry point, and tricking MW into thinking the call was made from a CLI. I now have a test case for the coordinate class, with tests for most of it’s functionality. Some more test data, and maybe some extra tests would be nice. A tricky thing in the case of this class is founding errors, which are hard to take into account, especially if you only want to allow them to a certain degree.
This particular test case is already paying off, as it made me find 3 subtle errors in coordinate parsing or formatting, that did not show up in my manual tests, as I was not covering the test data causing the issues.
I’m now planning to maybe write test cases for the distance parser to, which should be rather easy to do. I probably won’t create any others for Maps, as it’s rather time consuming, and I have a lot of other things to do right now. When I create new classes that are suited for unit tests in the future, I’ll definitely write tests for them as I build them up though, as it’ll not cost a lot more time then doing manual tests, and will ensure the classes are really solid.