ZeroDefects

Is Zero Defects doable?

I'd like to distiguish two scenarios. The first is creating a project from scratch, that is using TestDrivenDevelopment right from the start. The second is to introduce TestDrivenDevelopment and AgileMethodologies? after a substantial part of the software has already been created.

Scenario 1: The first case is much easier. I have done this and know from experience that it is possible to create products with zero known defects at the time of delivery. This does not mean that there are no bugs in the product. It just means that the development has tested everything that could possibly break. At least to their knowledge. Using frequent SprintReviewMeetings? and making available EarlyPrototypes? will help to sort out most of the issues before the final product is shipped.

Scenario 2: If a system has been developed with a different approach and you start introducing TestDrivenDevelopment and AgileMethodologies? after the fact, you have a long and rough ride in front of you. The bug rate is high, and you constantly have to devote substantial resources to fixing defects. It is almost impossible to find out the root cause for each single bug in order to avoid them in the future. You need a bug tracking system to not forget any of the many bugs. And this does not include an angry customer who may loose revenues because the service level is reduced.

However, this does not mean that you shouldn't try to achieve ZeroDefects in your product. Meeting this quality gate will still be increasingly difficult depending on the size of the product, whether it has been developed test-driven, and others. Having ZeroDefects will help you to become more productive, and will contribute to your customer's success.