Unit Tests from the Dark Ages

I was just leafing through my old copy of The Mythical Man Month. If you allow for memory size pretty much being a solved problem, it’s amazingly relevant after three decades:

Build plenty of scaffolding. By scaffolding I mean all programs and data built for debugging purposes but never intended to be in the final product. It is not unreasonable for there to be half as much code in scaffolding as there is in product.

One form of scaffolding is the dummy component, which consists only of interfaces and perhaps some faked data or some small test cases. For example, a system may include a sort program which isn’t finished yet. Its neighbors can be tested by using a dummy program that merely reads and tests the format of input data, and spews out a set of well-formatted meaningless but ordered data.

Heh. Eat your heart out, unit testers. It’s all been done before.