Part 1 of this article provided just a glimpse of what was behind the looking glass. Now we’re ready to dive in all the way and look at how we can apply test-driven development to games. Be warned: the looking glass is very much one-way only. After you try this, you might become test infected and may never be able to go back and write code the way you’ve done up until now.
If you’re a typical game developer, you probably don’t write any tests for the code you create. So how would you feel about not just writing tests, but creating them before the code they are testing? What if I told you those tests don’t even verify that the code you write is correct? “It’s madness,” you might say; “it’s all backwards!” Not really. It all makes sense in its own way. Follow me through the looking glass and I’ll show you the wonderful upside-down world of test-driven development and how we can apply it to games.
Update (Apr 2010): It’s been quite a few years since I originally did this comparison. Since then, Charles Nicholson and I created Unit Test++, a C/C++ unit-testing framework that addresses most of my requirements and wish-list items. It’s designed to be a light-weight, high-performance testing framework, particularly aimed at games and odd platforms with limited functionality. It’s definitely my framework of choice and I haven’t looked at new ones in several years because it fits my needs so well. I definitely encourage you to check it out.
One of the topics I’ve been meaning to get to for quite a while is the applicability of test-driven development in games. Every time the topic comes up in conversations or mailing lists, everybody is always very curious about it and they immediately want to know more. I will get to that soon. I promise!
In the meanwhile I’m now in the situation that I need to choose a unit-testing framework to roll out for my team at work. So, before I get to talk about how to use test-driven development in games, or the value of unit testing, or anything like that, we dive deep into a detailed comparison of existing C++ unit-testing frameworks. Hang on tight. It’s going to be a long and bumpy ride with a plot twist at the end.