It's really not as black and white as you seem to be imagining it. There's lots of prompting and asking questions. If they don't think of unit testing straight

It's really not as black and white as you seem to be imagining it. There's lots of prompting and asking questions. If they don't think of unit testing straight up, that's fine. It's just a nice indicator if they do think of it. Things generally flow as you describe - in a non-linear fashion. They'll get the basic method done and then I'll ask them about possible edge cases and error handling. The problem is that even with this prompting, many people can't come up with what those may be. And then, if I suggest what they may be (eg how should we handle nulls), how they go about handling that in their code is when it can sometimes become really messy. It's definitely not a failure. When a good programmer comes in, it's immediately obvious. They have no trouble. I mean, it really is basic stuff - writing a loop with a few if statements - not some fancy egg dropping puzzle or the big O notation stuff that Google gets you to do.