Make required input required in createActor (#4704)

* Make required `input` required in `createActor`

* fixed tests

.changeset/curly-moons-trade.md

@@ -0,0 +1,5 @@
+---
+'xstate': minor
+---
+
+`createActor` will now error if the required `input` is not given to it.

packages/core/src/createActor.ts

@@ -14,8 +14,11 @@ import { AnyActorSystem, Clock, createSystem } from './system.ts';
 import type {
   ActorScope,
   AnyActorLogic,
+  ConditionalRequired,
   DoneActorEvent,
   EventFromLogic,
+  InputFrom,
+  IsNotNever,
   Snapshot,
   SnapshotFrom
 } from './types.ts';
@@ -704,6 +707,9 @@ export class Actor<TLogic extends AnyActorLogic>
   }
 }
 
+type RequiredOptions<TLogic extends AnyActorLogic> =
+  undefined extends InputFrom<TLogic> ? never : 'input';
+
 /**
  * Creates a new actor instance for the given actor logic with the provided options, if any.
  *
@@ -738,7 +744,14 @@ export class Actor<TLogic extends AnyActorLogic>
  */
 export function createActor<TLogic extends AnyActorLogic>(
   logic: TLogic,
-  options?: ActorOptions<TLogic>
+  ...[options]: ConditionalRequired<
+    [
+      options?: ActorOptions<TLogic> & {
+        [K in RequiredOptions<TLogic>]: unknown;
+      }
+    ],
+    IsNotNever<RequiredOptions<TLogic>>
+  >
 ): Actor<TLogic> {
   return new Actor(logic, options);
 }

packages/core/test/guards.test.ts

@@ -1,4 +1,4 @@
-import { createActor, createMachine, raise } from '../src/index.ts';
+import { InputFrom, createActor, createMachine, raise } from '../src/index.ts';
 import { and, not, or, stateIn } from '../src/guards';
 import { trackEntries } from './utils.ts';
 
@@ -93,7 +93,7 @@ describe('guard conditions', () => {
   });
 
   it('should transition if condition based on event is met', () => {
-    const actorRef = createActor(lightMachine).start();
+    const actorRef = createActor(lightMachine, { input: {} }).start();
     actorRef.send({
       type: 'EMERGENCY',
       isEmergency: true
@@ -102,7 +102,7 @@ describe('guard conditions', () => {
   });
 
   it('should not transition if condition based on event is not met', () => {
-    const actorRef = createActor(lightMachine).start();
+    const actorRef = createActor(lightMachine, { input: {} }).start();
     actorRef.send({
       type: 'EMERGENCY'
     });

packages/core/test/input.test.ts

@@ -52,6 +52,7 @@ describe('input', () => {
       }
     });
 
+    // @ts-expect-error
     const snapshot = createActor(machine).getSnapshot();
 
     expect(snapshot.status).toBe('error');

packages/core/test/types.test.ts

@@ -5,6 +5,7 @@ import { stopChild } from '../src/actions/stopChild';
 import { PromiseActorLogic, fromCallback, fromPromise } from '../src/actors';
 import {
   ActorRefFrom,
+  InputFrom,
   MachineContext,
   ProvidedActor,
   Spawner,
@@ -4339,3 +4340,20 @@ describe('self', () => {
     });
   });
 });
+
+describe('createActor', () => {
+  it(`should require input to be specified when it is required`, () => {
+    const logic = fromPromise(({}: { input: number }) => Promise.resolve(100));
+
+    // @ts-expect-error
+    createActor(logic);
+  });
+
+  it(`should not require input when it's optional`, () => {
+    const logic = fromPromise(({}: { input: number | undefined }) =>
+      Promise.resolve(100)
+    );
+
+    createActor(logic);
+  });
+});