- Token model structure: verify $casts has datetime fields, $fillable
is complete, and $table is set correctly (catches $dates→$casts regression)
- ClientServiceProvider: verify DeferrableProvider interface is
implemented and provides() returns Client::class (catches $defer regression)
- Token parseOauthToken: verify stored values and Carbon types, not
just that mock methods were called
- Client setToken: verify DataService cache is cleared on token change
- Client delegation: verify hasValidAccessToken/hasValidRefreshToken
delegate to Token correctly
