What problem does it solve? Writing tests after implementation often leads to fragile tests that verify internal details instead of behavior, and skipping disciplined cycles produces untested or over-engineered code. This Skill enforces a strict Test-Driven Development workflow so tests drive design and refactoring stays safe. ## Core Features & Use Cases - Red-Green-Refactor Discipline: Enforces writing a failing test first, implementing the minimum code to pass, then refactoring only after green. - Test Double Guidance: Clarifies when to use dummies, stubs, spies, and mocks, with a rule to mock only at architectural boundaries like databases and networks. - Behavior Over Implementation: Prevents test-induced design damage by testing public API contracts instead of private internal state. - Use Case: When building a pricing module with discount rules, write the failing test for the desired API first, implement the minimal logic, then refactor constants and structure with tests guaranteeing behavior. ## Quick Start Use the tdd-workflow skill to build a discount calculation function using strict Red-Green-Refactor cycles.
