Test-Driven Development with Python, 3rd Edition

Obey the Testing Goat!

Let’s get back to the Testing Goat.

“Groan”, I hear you say—“Harry, the Testing Goat stopped being funny about 17 chapters ago”. Bear with me; I’m going to use it to make a serious point.

Testing Is Hard

I think the reason the phrase “Obey the Testing Goat” first grabbed me when I saw it was that it spoke to the fact that testing is hard—​not hard to do in and of itself, but hard to stick to, and hard to keep doing.

It always feels easier to cut corners and skip a few tests. And it’s doubly hard psychologically because the payoff is so disconnected from the point at which you put in the effort. A test you spend time writing now doesn’t reward you immediately; it only helps much later—​perhaps months later when it saves you from introducing a bug while refactoring, or catches a regression when you upgrade a dependency. Or, perhaps it pays you back in a way that’s hard to measure, by encouraging you to write better-designed code, but you convince yourself you could have written it just as elegantly without tests.

I myself started slipping when I was writing the test framework for this book. Being quite a complex beast, it has tests of its own, but I cut several corners. So, coverage isn’t perfect, and I now regret it because it’s turned out quite unwieldy and ugly (go on; I’ve open sourced it now, so you can all point and laugh).

Keep Your CI Builds Green

Another area that takes real hard work is continuous integration. You saw in Chapter 25 that strange ...