TDD

Drive strict red-green-refactor. The inner loop for any behavior change.

When to Use

Writing any new behavior, fixing a bug, or refactoring code that needs coverage. Works on one unit at a time — typically a unit from an approved scope plan.

Steps

1. Write the smallest failing test that captures the next behavior.
2. Run it; confirm it fails for the expected reason.
3. Write the minimum production code to make it pass.
4. Run the full suite; confirm green.
5. Refactor with the tests green.

Rules