A few days ago I wrote about Continuous Unit Testing (CUT) and why the need for CUT was a sign of other problems. The last days I have been thinking about CUT a little bit more and I still find CUT questionable but there is another thing - CAT (Continuous Acceptance Testing) that I find very useful.

Acceptance tests are typically slower than unit tests since they involve several components that are not faked in any way and that may need extensive setup work. So acceptance tests are often much slower than unit tests. The unit tests created as part of the BDD (or TDD) cycle are probably enough to catch most problems but in some cases things will be caught in automated acceptance tests. And since that is the case you have much to gain from running those acceptance tests as often as possible. So why not run them AL the time (continuously) in the background?