Ok. I'm not actually that wedded to the order you do the two operations in. I think there is some value in writing tests first, so that you can verify they fa

Ok. I'm not actually that wedded to the order you do the two operations in. I think there is some value in writing tests first, so that you can verify they fail (before the code is written) and then work (once it is complete). But I think it's less important to do them first than to do them. IMO, the "killer app" for unit tests is regression testing. If I make a change and the test suite still passes, I can be reasonably sure that I didn't break anything. All the other benefits are "nice to haves" in my mind.