I object to the TDD fundamental precept that you code to the tests. That narrows the 'testing' until its a self-fulfilling prophecy that you will have 'fewer bugs', since you defined the bugs as 'what we're looking for'.

Reminds me of the old joke "A: I'm looking for my wallet. B: where did you lose it? A: over there. B: then why look here? A: the light's better"