Verdict
A pragmatic, seam-oriented TDD guide that insists on observing the failure before implementation and favors tests through public behavior. It is especially useful when coding agents otherwise add tests after the fact to bless what they already wrote.
Best for
Features and bug fixes with stable behavioral seams and a test runner that can provide fast feedback.
Keep in mind
Its strict loop is not suited to disposable prototypes, generated artifacts, or visual exploration, and its philosophy differs from frameworks that place refactoring inside every cycle.
Example task
Add idempotent webhook processing one externally visible behavior at a time, proving every new test fails for the intended reason first.