Test-Driven Development

Implement the requested feature using strict TDD: red, green, refactor.

Use this when adding or changing behavior. Do not use this to recover an already failing test suite (use fix-and-test) or to perform behavior-preserving cleanup only (use refactor).

What to do

1. Read the feature requirement from the argument.
2. Add or update one test that expresses the next behavior slice.
3. Run the targeted test and confirm it fails first (red).
4. Implement the smallest change to pass that test (green).
5. Refactor with all tests still green before starting the next slice.

Flow