Seems to come back to the question of whether you can hold the whole program in your head. If so then it's simple to figure out what needs to be tested and wha

Seems to come back to the question of whether you can hold the whole program in your head. If so then it's simple to figure out what needs to be tested and what doesn't. One ancillary benefit of TDD is that it increases your confidence for a release. Confidence allows you to release and promote your code without fear that you'll be up all night fixing bugs.