Ron Jeffries published a wonderful post titled “working software“. He quotes the agile manifesto “working software is the primary measure of progress”.

Now, he explains that what exactly “working software” means depends (as always). But in general,

Working software is real. It works. It can be tested. It can be verified. Questions about whether it does X are readily answered with “Yes” or “No”. The less ambiguity there is in our answers—our true answers—the closer to “working software” we are.

And he shares his opinion on “best development style”:

The best development style we know today, whether working solo, in pairs, or in a mob, is to pick a very small thing that the system doesn’t as yet do, verify that it doesn’t do it, then make it do that thing, verifying again, and keeping the code at or above our standard of internal quality.

How small should that thing be? Tiny. Smaller than that. No, smaller still.

I repeat that:

  1. pick a very small thing that the system doesn’t do yet
  2. verify it doesn’t do it (the “red” step in the TDD cycle)
  3. make it do that thing
  4. verify it does it (the “green” step in TDD)
  5. keeping the code at or above our quality standard (the “refactor” step in TDD).

I really like that. It’s not always that easy. But more often than not.

I know of TDD but I need to get better at remembering this (I’ll put that in my Anki deck) – including the very small part – and then practice it.