Merge branch 'next' of https://github.com/cerebral/overmind into next

Author: christianalfoni

packages/node_modules/overmind/src/statemachine.ts

@@ -10,10 +10,28 @@ export type StatemachineTransitions<States extends TStates> = {
   [State in States["state"]]: Array<States["state"]>
 }
 
-export type Statemachine<States extends TStates> = States & {
+export interface MachineMethods<States extends TStates> {
   reset: () => void
+  matches<T0 extends States["state"]>(arg0: T0): this is Statemachine<States> & (States extends { state: T0 } ? States : never);
+  matches<
+    T0 extends States["state"],
+    T1 extends States["state"],
+  >(state0: T0, state1: T1): this is Statemachine<States> & (States extends { state: T0 } ? States : never) & (States extends { state: T1 } ? States : never);
+  matches<
+    T0 extends States["state"],
+    T1 extends States["state"],
+    T2 extends States["state"],
+  >(state0: T0, state1: T1, state2: T2): this is Statemachine<States> & (States extends { state: T0 } ? States : never) & (States extends { state: T1 } ? States : never) & (States extends { state: T2 } ? States : never);
+  matches<
+    T0 extends States["state"],
+    T1 extends States["state"],
+    T2 extends States["state"],
+    T3 extends States["state"],
+  >(state0: T0, state1: T1, state2: T2, state3: T3): this is Statemachine<States> & (States extends { state: T0 } ? States : never) & (States extends { state: T1 } ? States : never) & (States extends { state: T2 } ? States : never) & (States extends { state: T3 } ? States : never);
   whenTransitioned: (state: States["state"]) => Promise<void>
-} & {
+}
+
+export type Statemachine<States extends TStates> = States & MachineMethods<States> & {
   [State in States["state"]]: <O>(entry?:  (current: Statemachine<States> & (States extends { state: State } ? States : never)) => O, exit?: (current: Statemachine<States> & (States extends { state: State } ? States : never)) => void) => O
 }
 
@@ -54,6 +72,13 @@ class StateMachine<States extends TStates>  {
       return aggr
     }, this)
   }
+  matches(...states) {
+    if (states.includes(this.state)) {
+      return true
+    }
+
+    return false
+  }
   reset() {
     const exit = this[VALUE][CURRENT_EXIT]
     if (typeof exit === 'function') {