tdd

What problem does it solve? Teams often write tests after implementation or in bulk, producing tests coupled to internal structure that break on refactors and fail to catch real bugs. This Skill enforces a disciplined red-green TDD loop so tests verify observable behaviour through public interfaces. ## Core Features & Use Cases - Red-Green Loop Enforcement: One failing test, the minimum code to pass it, repeated one behaviour at a time with a per-cycle checklist. - Seam-Based Testing: Agree on public test boundaries before writing the first test, avoiding tests of private methods or mocked internals. - Anti-Pattern Guidance: Reference docs cover implementation-coupled tests, tautological assertions, mocking at system boundaries, deep modules, and interface design for testability. - Use Case: When building a new checkout feature, use this Skill to drive development test-first: confirm the public seam, write one failing test for cart confirmation, implement the minimum code, and repeat until all behaviours are covered. ## Quick Start Use the tdd skill to build this feature test-first with a red-green loop, one behaviour at a time.