The XP Circle of Life helps keep projects alive. A key aspect of this cycle is the Acceptance Test. Acceptance Tests are critical to communication among team members, especially between customer and programmer.

When unexpected defects arise, it can take a long time to isolate the problem. This can have large and unpredictable impact on the team’s progress. Extreme teams release software frequently, keeping their unit tests at 100 percent. The result is smoother progress toward completion, fewer unhappy surprises, and continuing improvement in quality.