It always annoys me when people talk about test automation (TDD, unit testing, whatever) in the context of "finding bugs".
Test automation is about preventing bugs.
Test automation is about preventing bugs.
However, unit testing is also a nice way to find bugs. In any case, "trapping" a bug like I did in this article is often an effective way of introducing newcomers to what a unit test is.
I didn't mean my nit-picking to come across as harsh and dismissive. I just get hung up on people talking about writing tests to find bugs, because if that's all it is about, manual testing is generally faster in the short-run.