Monday, December 24, 2007

Quality Software vs Healthy Software

I found a 2004 talk by Kent Beck(mp3) on the Topic of Developer Testing on He talks about developer testing(unit testing) and how it leads to Healthy Software. I like the distinction he makes between Quality Software and Healthy Software. Quality Software is software that currently works as designed and lacks bugs. In contrast Healthy Software is software responds well to changes over time. It is possible to have Quality Software without developer testing but healthy software relies on developer testing. I've had to maintain a lot of Unhealthy software that's falling apart at the seams. Some of it was likely considered quality software in the first deployment, but lack of documentation and lack of unit testing doomed it to failure over time. If you need encouragement getting yourself or your team started in unit testing this is an excellent pep-talk.