Test First

Overview

Red-green-refactor TDD with strict evidence requirements. The skill exists because the most common testing failure isn't missing tests — it's tests written after the code, designed to pass against the implementation rather than to specify it. Test-first inverts the order: a failing test asserts the desired behavior, the smallest implementation makes it pass, and refactoring runs with the test as a safety net. Each step produces test runner output that goes into the PR. The skill is for engineers shipping production code — not a TDD evangelism doc.

When to Use