Testing is like a box of rocks

I was inspired today by Alan Page’s Test Automation Snowman. He makes all good points, but let’s be honest, the model is the same as the good ol’ test pyramid. The only difference is that he’s being explicit about tests at the top of the pyramid being slow and tests at the bottom being fast. Ok, so maybe the snowman thing is a joke, but it did make me think about what might make a better visualization. I quickly doodled something on a sticky note:

A sticky note with a lot of tiny circles in the bottom third, medium circles in the middle third, and a few large circles in the top third.

If the point we want to emphasize is that UI tests are slow (and therefore take a lot of time), we should include that in the visualization! The problem with the pyramid (and the snowman) is that the big tests take up the least amount of space; the small triangle at the top makes it look like having fewer UI tests also means you do less UI testing.

It doesn’t.

At least, not proportionately. If you had an equal number of UI and unit tests, it’s a safe bet that you’re going to spend more of your time working on the UI tests.

So instead, let’s say testing is like a box of rocks. Each rock is a test, and I have to choose how to allocate the space in that box to fit all the rocks that I want. A few big rocks are going to take up a lot more space than a bunch of tiny pebbles. Unless I have a good reason why that big boulder is a lot more interesting than the hundred little rocks I could put in its place, I’m going to go for the little rocks! If I have to add a new rock (to kill a new bug, say) I probably want to choose the smallest one that’ll still do the job.

You can still think about the different levels (unit vs API vs UI, for example) if you picture the little rocks at the bottom forming a foundation for bigger rocks on top. I don’t know if rocks work like that. Just be careful not to get this whole thing confused with that dumb life metaphor.

Ok, it might not be the best model, but I’ll stick with it for now. And like the Alan’s snowman, you’re free to ignore this one too.