> The trouble with TDD is that quite often we don't really know how our programs are going to work > The obvious exception to this, where I still use TDD, is w

> The trouble with TDD is that quite often we don't really know how our programs are going to work > The obvious exception to this, where I still use TDD, is when implementing a well defined spec. From my understanding (and experience), TDD is quite the opposite. It's most useful when you don't have the spec, don't have clue how software will work in the end. TDD creates the spec, iteratively.