My beef against testing is that I often see it adopted (and often subtly pushed) as an alternative to thinking through the logic carefully -- Why mess with the if statements, my tests will catch the errors if any. Should I index the array with i or i+1 ? I will just test what works. Should I loop till n-1 or n-2. Let me just stick with n-2 and add a test...

The problem is that to write tests that really ensure that the logic is correct you really need to think through the logic really hard. Just spraying the code with a few tests that happen to come to the mind is not enough.

I am yet to see a convincing argument that shows that coming up with a sufficient number of (unit)tests from a specification is any easier than getting the logic right.

Testing is well intentioned but often abused as an excuse to be sloppy.