I don't think tests are necessary for bits of throw away code. Nor for simple scripts that are only intended to be used by me. Do you think otherwise?

No. Bod, I think you're doing a great job. I trust you appreciate from my numerous Coventry working-class asides, I just enjoy teasing you. :)

Of course, working as a professional programmer for large companies is a completely different ball game. If you ship buggy code that upsets a big important customer, you might even be subjected to a probing Five Whys post mortem. For still more pressure, as indicated at On Interfaces and APIs, try shipping a brand new public API to thousands of customers, with only one chance to get it right.

I might add that when I'm doing recreational programming (as I've been doing quite a bit lately) I tend to just hack out the code without using TDD. In the tortuously long Long List is Long series, for example, I haven't written a single test, just test the output of each new version manually via the Unix diff command. Update: finally wrote my first LLiL unit test on Mar 01 2023.

Of course, I could never get away with that at work, where you are not permitted to check in new code without passing peer code review (where you will be grilled on how you tested your code) and where you will typically check in accompanying unit and system test changes in step with each code change.

For my personal opinion on how to do software development in large companies see: Why Create Coding Standards and Perform Code Reviews?