Because of this, I find the spike-and-stabilise pattern troubling in the large and manageable in the small. By this, I mean that so long as one keeps the spikes quite small, one can get away with stabilising it with tests after the fact. I can’t easily define “small enough” here, as I imagine it depends on a host of factors that I can’t enumerate well enough to try. Perhaps one learns “small enough” from experience. (Does that make the whole statement beg the question? It might.) Perhaps I do better to say the size of thing one can safely spike-and-stabilise varies from programmer to programmer, and most programmers most of the time overestimate what they can safely spike-and-stabilise, so I urge them to err on the side of spike-and-rewrite.

How to “increase” the size of thing one can safely spike-and-stabilise? Build more stuff well, observe your blindspots, notice your design tendencies, write code in reversible steps, use version control aggressively, reach the point where you can see 10 tests ahead. You’ll probably still write the tests in your head, or at least sketch out the sets of tests in your head, but not write them. You’ll use other techniques to lower the cost of mistakes. It’ll be fine. I feel comfortable doing this now; I refactor without tests quite a lot; it took me at least five years to become even the slightest bit comfortable with it. Everyone differs in how long it will take. Everyone probably underestimates how long it will take. Everyone probably overestimates how ready they are.

But you’re right, I’m conflating the issue, as well as mixing it up with the fact that when I do BDD at a unit level I tend to write pretty nice code (because I’m thinking about the responsibilities of the classes, etc.).

I think of the TDD cycle as producing good, clean code at the end, regardless of whether it happens that way because of nice BDDism or because we clean it up one small bit at a time. I would love people to have the ability to produce good, clean code when there’s more than just a small bit to clean up, and I believe that skill is different, and hugely important. Thank you for prompting me to clarify my thoughts here.