Yep, TDD for little chunks of code is really nice, I think of it like just a more structured way to trying things out in a repl as you go (and it works for languages without repls). Even if you decide to never check the test in because the chunk of code ended up being too simple for a regression test to be useful, if it was helpful in testing assumptions while developing the code, that's great.

But yeah, trying to write all the tests for a whole big component up front, unless it's for something with a stable spec (eg. I once implemented some portions of the websockets spec in servo, and it was awesome to have an executable spec as the tests), is usually an exercise in frustration.