This "simple" example of an uppercase stored proc is a very good choice for another reason: testing just one string will not be enough. A company with users in more than one country would need to use test data in the languages of all its major customers - including those with character sets that may not even have the concept of uppercase. Collecting realistic test data could be a major effort in itself, but once that is done a TDD environment would have no problem processing it.

Although I can see the benefit of formal TDD, it does add a considerable overhead in tools, training, storage, reporting and the like. It assumes that the complex infrastructure that was in place during the initial development will still be there when version 2 comes along. This may not be the case for small to medium-size projects. Also, when the focus shifts to testability, what happens to the other "ilities" like scalability and maintainability?