Well, the testfest 2008 is wrapping up and a lot of the tests are now a part of the php distribution. php.no had a session where Hannes Magnusson introduced us to writing tests. I focused on some SPL areas that didn’t have coverage, and I got myself a elephant! ( check out the flickr group if you are unfamiliar with it)
The testfest is a great introduction to the internals of php and will teach you a lot when it comes to the behavior of the functionality you touch on, so next year: meet up at your local testfest and participate in getting the code coverage for php even higher ( or just digg into writing tests now! ).