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.
Тестирует переходы конечного автомата с помощью шаблонов в стиле XState. Проверяет матрицы переходов, защитные таблицы истинности, мутации контекста и обработку состояний терминала. Источник: apankov1/quality-engineering.