tdd

<objective> TDD enforces the Iron Law -- no production code without a failing test first -- through a strict RED-GREEN-REFACTOR loop: detect the stack and test framework, write one failing test for the next behavior, verify it fails for the *expected* reason (not a syntax error or missing fixture), write the simplest code that passes it, verify the full suite is green, refactor while staying green, then repeat for the next behavior. It never skips a VERIFY step -- a test that passes on first run proves nothing and must be investigated, not accepted. </objective> # TDD Skill Write the test first. Watch it fail. Write minimal code to pass. ## The Iron Law **No production code without a failing test first.** Every line of production code must be justified by a test that failed without it. No exceptions. No shortcuts. No "I'll test after." --- ## Agent Workflow ``` 1. DETECT -> Identify stack, test framework, existing test patterns 2. RED -> Write ONE failing test for the next behavior 3. VERIFY -> Run test, confirm it fails for the EXPECTED reason IF the test fails for a DIFFERENT reason (syntax error, wrong import, missing fixture) → fix the test itself and re-run. Do NOT proceed to GREEN until the failure matches the intended behavior. 4. GREEN -> Write the SIMPLEST code that makes the test pass 5. VERIFY -> Run tests, confirm ALL pass (new + existing) 6. REFACTOR -> Clean up while keeping all tests green 7. REPEAT -> Next behavior = next failing test ```...