Characterize the Mess First, Then Make One Safe Change

Описание и применение

Пошаговый процесс документирования текущего поведения модуля и создания тестов‑характеризаций, чтобы безопасно рефакторить без нарушения контрактов.

Задача

A small helper module contains hidden state, silent fallbacks, and inconsistent rounding, causing callers to rely on undocumented behavior that unit tests miss.

Результат

The workflow ensures that refactoring a messy helper does not alter existing contracts by first documenting current behavior and then making incremental changes.

Рабочий процесс

• 1. Search repository for all quoteTotal( call sites and record arguments.
• 2. Note hidden coupling such as setLoyalty and tests that don't reset it.
• 3. Capture one production-shaped input per call site, including missing flags.
• 4. Write an inventory table before writing tests.
• 5. Create characterization tests that assert current results, naming tests after observed behavior.
• 6. Use afterEach to reset global loyalty state.
• 7. Refactor only one small change at a time, guided by the characterization tests.

Доказательства

Characterization tests exist for that gap between a green suite and the behavior callers already shipped.

Источник

Global loyalty state leaks across tests when a file forgets to reset it after a run.

Источник