[jlouis]

I don't particularly find unit testing to be effective in programming. While naivety is often a dominating factor, it does not have to be so. First, you should note that you might have a different notion of proper than other people. Second, I don't think you can rank programming inventions. Undoubtly, unit testing is useful. The question one should ask is rather: is it effective? In this question we also lace in the factor of time spent.

Note that the most important programmer commodity is time. Time spent on a unit test means less time to write the program. Now, what ought to tip the scale is that later changes are easier to get right so in the long run, one should win time by writing down unit tests.

But personally, I think that there are other practices which are more effective: Static typing, assertions and automated test harnesses for the whole program. I'll choose to spend my time on these rather than unit testing.