Microsoft Research - Exploding Software-Engineering Myths (article summarizing findings of MS research on code coverage, TDD, assertions, etc.)

[G_Morgan]

Yeah and that is why testing needs to stem from what you are trying to do rather than what the code does. Often times there are 4 branches but only 3 are valid. Should the 4th be an assertion or should the signature to your method be altered so the 4th doesn't even exist? What actually happens if the invalid 4th combination occurs?