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.
Teste les transitions de machine à états avec des modèles de style XState. Valide les matrices de transition, les tables de vérité de garde, les mutations de contexte et la gestion de l'état terminal. Source : apankov1/quality-engineering.