tdd-mastery

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# 🧪 TDD MASTERY: THE IRON LAW

> **Philosophy:** If you didn't watch the test fail, you don't know if it tests the right thing. TDD is not optional—it's the foundation of trustworthy code.
**TEST-FIRST INTEGRITY MANDATE (CRITICAL):** Never write production code before a test exists and has been seen failing. AI-generated code often attempts to write implementation and tests simultaneously or implementation first. You MUST strictly adhere to the Red-Green-Refactor cycle. Any code submitted without a preceding failing test or that generates tests after the implementation must be rejected as "Legacy Code on Arrival".