I don't write tests for all my code. But if I'm not writing an automated test (frequently when I'm writing a single-use script, which is something I do a lot, a

I don't write tests for all my code. But if I'm not writing an automated test (frequently when I'm writing a single-use script, which is something I do a lot, as I'm merely a hobbyist), I still "test" my code, function by function, at a REPL. I've long since learned the hard way that if you don't test the functions as you write them, the bugs get buried in the system, and become very hard to find. When you test your code as you write it and modify it (formally on larger projects, informally on smaller ones) this doesn't happen. That's the advantage of tests, so I can get Beck's point: If the function is so painfully simple that you already know if it's right, (say, an accessor) just by looking, then it's not worth writing a test for it.