What problem does it solve? Code changes and bug fixes often ship without tests that actually protect the behavior, leading to regressions and untrustworthy test suites. This Skill enforces a disciplined test-first workflow so every behavior change is defined and guarded by a failing test before implementation begins. ## Core Features & Use Cases - Red-Green-Refactor Cycle: Write a failing test that reaches its assertion (strong RED), implement the minimal code to pass (GREEN), then clean up while tests stay green. - Regression Tests for Bugs: Reproduce any reported bug with a failing test before attempting a fix, proving both the defect and the fix. - Test Design Guidance: Apply the test pyramid, test size classification (small/medium/large), specification-based and structure-based case selection, test oracles, and anti-pattern avoidance. - Use Case: A bug report says completing a task does not set its timestamp. Write a failing test asserting completedAt is a Date, confirm it fails, implement the fix, and watch the test pass with no regressions. ## Quick Start Ask the AI to implement a new feature or fix a bug using test-driven development, starting with a failing test that reproduces the expected behavior.
