model-based-testing

Test state machines systematically — don't guess at valid transitions.

State machines are everywhere: workflow states, lifecycle management, game turns, circuit breakers. Most bugs come from invalid transitions being allowed or valid transitions being blocked. This skill teaches you to systematically test ALL state pairs, not just the happy path.

When to use: Any code with named states, lifecycles (initializing → ready → stopping), workflow progressions (draft → review → published), turn-based systems, circuit breakers, or XState machines.

使用 XState 樣式模式測試狀態機轉換。驗證轉換矩陣、保護真值表、上下文突變和最終狀態處理。 來源：apankov1/quality-engineering。