Unit tests just paid off bigtime. An underlying python library changed the return type of one of its functions. If we hadn't written unit tests, our output would have been garbage, and if we even noticed it, finding out where in the pipeline things went wrong would have been a nightmare.
@peterdrake I wonder, did you test the library itself or just your code?
@tnoisu Just our code that calls the library.
I think Clean Code recommends testing the library, both for this reason and as a way of figuring out / documenting how to use the library.
