[josepot]

Test coverage is a very dangerous metric. IMO it will only be useful the day that we find a way to not take into account those tests that are testing implementation details. Every time that I see a high number being enforced, the end result is always a disaster: lots of poor quality tests that are only there in order to bump up that metric. Those tests are poison: they don't aim to test correctness, they make refactors/improvements a PITA, they just lock you down to a concrete implementation and they don't even give you any guarantees that your code works correctly.

[AgloeDreams]

Bingo, this *1000.

Your team ends up spending half their time writing painful depressing tests that are bad afterthoughts. Generally with TONS of mocks and little real meaning.

[cbanek]

The other half of the time is spent editing the tightly coupled mocks/tests when you refactor the real code. Bad tests can be a liability, not an asset.