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.
Testa le transizioni delle macchine a stati con modelli in stile XState. Convalida matrici di transizione, tabelle di verità di guardia, mutazioni di contesto e gestione dello stato terminale. Fonte: apankov1/quality-engineering.