tdd

1# TDD
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3Red. Green. Refactor. In that order, every time.
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5## Hard Rules
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7- No production code without a failing test first.
8- If production code was written before its test, delete it and start over with a failing test.
9- Never skip the red step. A test that has never failed proves nothing.
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11## Cycle
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13For each unit of behavior:
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151. **Red** — Write a test for the next behavior. Run it. It must fail. Read the failure message — it should describe the missing behavior.
162. **Green** — Write the minimum production code to make the test pass. Nothing more. Run the test. Apply the `verify` skill.
173. **Refactor** — Clean up both test and production code. Run the test again. Still green? Done. Apply the `verify` skill.
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19Then pick the next behavior and repeat.
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21## Rules for Each Step
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23**Red:**
24- Test one behavior, not one function. Name the test after what the system should do, not what the function is called.
25- The test must fail for the right reason — a missing method, wrong return value, unmet condition. Not a syntax error or import failure.
26- If the test passes immediately, it's not testing new behavior. Delete it or pick a different behavior.
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28**Green:**
29- Write the simplest code that passes. Hardcode if needed — the next test will force generalization.
30- Do not add code "while you're in there." If it's not required by a failing test, it doesn't exist yet.
31- Do not refactor during green. Pass first, clean second.
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33**Refactor:**
34- Remove duplication between test and production code.
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