[GrinningFool]

That's the biggest drawback of any kind of tests - there is always the risk of testing the wrong thing, or not testing enough of the possible right things. and you're absolutely right - because the test is also code, it also can and often will have bugs.

When you write tests for what you're about to code, or what you just finished coding, it's a challenge to write a test that is not flawed in the same way the code is - because you don't know the flaw is there in order to test for it.

By thinking things out first you can decrease the number of these (and enforcing that discipline is a major plus for TDD ) but for typical non-trivial application without a lot of control over its inputs, it's close to impossible to do.

Tests are often reactive as well - because the changes that require them are reactive (bugs, new reqs, arch changes, etc). That doesn't detract from the value of them, but it's a limitation that explains well why even 100% coverage never stops the bugs from showing up.

I think I'd be happier with TDD if fewer people presented it as if it solved all the problems. TDD is a powerful tool, but tools are only as omniscient as the people who use them.