fix(overmind): fix events typing and base

Author: christianalfoni

packages/node_modules/overmind/src/statemachine.test.ts

@@ -11,9 +11,8 @@ describe('Statemachine', () => {
       current: 'BAR'
     }
 
-    const state = statemachine<States>({
-      FOO: ['BAR'],
-      BAR: ['FOO']
+    const state = statemachine<States, { type: 'TEST'}>({
+      TEST: () => {}
     }).create({
       current: 'FOO'
     })
@@ -40,9 +39,8 @@ describe('Statemachine', () => {
       foo: string
     }
 
-    const state = statemachine<States, never, BaseState>({
-      FOO: ['BAR'],
-      BAR: ['FOO']
+    const state = statemachine<States, { type: 'TEST' }, BaseState>({
+      TEST: () => {}
     }).create({
       current: 'FOO',
     }, {
@@ -273,9 +271,8 @@ describe('Statemachine', () => {
       }
     }
 
-    const state = statemachine<States>({
-      FOO: ['BAR'],
-      BAR: ['FOO']
+    const state = statemachine<States, { type: 'TEST'}>({
+      TEST: () => {}
     }).create({
       current: 'FOO',
       obj: {

packages/node_modules/overmind/src/statemachine.ts

@@ -15,8 +15,10 @@ type TEvents = {
 }
 
 
-export type StatemachineTransitions<States extends TState, Events extends TEvents> = {
-  [Type in Events["type"]]: ((state: States, payload: Events extends { type: Type } ? Events["data"] : never) =>  States | void)
+export type StatemachineTransitions<States extends TState, Events extends TEvents, BaseState extends IState> = {
+  [Type in Events["type"]]: [BaseState] extends [never] ?
+    ((state: States, payload: Events extends { type: Type } ? Events["data"] : never) =>  States | void) :
+    ((state: States & BaseState, payload: Events extends { type: Type } ? Events["data"] : never) =>  States | void)
 }
 
 export interface MachineMethods<States extends TState, Events extends TEvents, BaseState extends IState> {
@@ -40,7 +42,7 @@ const BASE_STATE = Symbol('BASE_STATE')
 export class StateMachine<State extends TState, Events extends TEvents, BaseState extends IState>  {
   current: State["current"]
   private [INITIAL_STATE]: State["current"]
-  private [TRANSITIONS]: StatemachineTransitions<State, Events>
+  private [TRANSITIONS]: StatemachineTransitions<State, Events, BaseState>
   private [STATE]: any
   private [BASE_STATE]: BaseState
   private [IS_DISPOSED] = false
@@ -55,7 +57,7 @@ export class StateMachine<State extends TState, Events extends TEvents, BaseStat
     })
     this[VALUE][IS_DISPOSED] = true
   }
-  constructor(transitions: StatemachineTransitions<State, Events>, state: State, baseState: BaseState) {
+  constructor(transitions: StatemachineTransitions<State, Events, BaseState>, state: State, baseState: BaseState) {
     this[STATE] = state
     this[BASE_STATE] = baseState
     this[INITIAL_STATE] = state.current
@@ -105,7 +107,7 @@ export type StatemachineFactory<States extends TState, Events extends TEvents, B
   create(state: States, baseState: BaseState): Statemachine<States, Events, BaseState> 
 }
 
-export function statemachine<States extends TState, Events extends TEvents = never, BaseState extends IState = never>(transitions: StatemachineTransitions<States, Events>): StatemachineFactory<States, Events, BaseState> {
+export function statemachine<States extends TState, Events extends TEvents, BaseState extends IState = never>(transitions: StatemachineTransitions<States, Events, BaseState>): StatemachineFactory<States, Events, BaseState> {
    return {
      create(state, baseState) {
       return new StateMachine(transitions, state as any, baseState as any)