What problem does it solve? Writing tests after code often produces brittle, implementation-coupled tests that break on every refactor. This Skill enforces a disciplined red-green test-driven development loop so tests verify behavior through public interfaces and survive refactors. ## Core Features & Use Cases - Red-Green Loop Rules: Enforces writing a failing test first, then only enough code to pass it, one vertical slice at a time. - Seam-Based Testing: Defines tests at pre-agreed public interface seams, confirmed with the user before any test is written. - Anti-Pattern Detection: Identifies implementation-coupled, tautological, and horizontally-sliced tests, with mocking guidelines restricted to system boundaries. - Use Case: When building a new checkout feature, use this Skill to agree on the public seams, write one failing behavior test, implement the minimal code to pass it, and repeat until the feature is complete. ## Quick Start Ask the assistant to build the next feature test-first using the tdd skill, starting by agreeing on the public seams to test.
