Matt Pocock / tdd
Which TDD skill should you actually install?
Two good options, and installing both is the one clear mistake.
What to remember
- Vertical slices keep the system runnable at every step.
- It is lighter than superpowers TDD, which suits teams that do not want a full methodology.
- Two TDD skills at once is a conflict, not a belt and braces setup.
- The refactor step is the one people skip, and the one that pays.
01What it changes in practice
Slicing vertically means each cycle produces something that runs, rather than a layer that only becomes useful once three more layers exist. With an agent that matters more than usual, because a half built layer cake is impossible to verify.
The narrower the slice, the more useful the cycle. A slice that takes six steps to pass has already stopped being a slice.
02Where it disappoints
It assumes a test setup that already works. In a codebase where running one test takes minutes, the loop is too slow to hold anyone's discipline.
It also does not decide what to build. Slicing well is a design skill that the process supports but does not supply.
Install and first run
- Install it with the skills CLI from mattpocock/skills, published under MIT.
- Define the first slice narrowly enough that it can be finished in one cycle.
- Refactor while the tests are green, never while they are red.
Questions people actually ask
- How is it different from the superpowers TDD skill?
- It is lighter and slice oriented, while superpowers embeds TDD in a wider methodology with planning and verification skills around it.
- Can I install both?
- You can, but you should not. They will give the agent conflicting instructions for the same job.
- What is a vertical slice?
- A thin path through the whole system that actually runs, rather than one complete layer that does nothing on its own.
Sources
Machine readable versions of this page