From e21e3f959971efbe1add5646a0adef04cf913524 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mateusz=20Burzy=C5=84ski?= <mateuszburzynski@gmail.com>
Date: Thu, 30 Nov 2023 07:21:04 +0100
Subject: [PATCH] Fixed an issue with contextual parameters in input factories
 of input-less actors (#4523)

* Fixed an issue with contextual parameters in input factories of input-less actors

* Changeset

---------

Co-authored-by: David Khourshid <davidkpiano@gmail.com>
---
 .changeset/khaki-bees-melt.md          |  5 +++++
 packages/core/src/actors/callback.ts   | 14 +++++++++-----
 packages/core/src/actors/observable.ts | 20 +++++++++++++++-----
 packages/core/src/actors/promise.ts    |  6 +++---
 packages/core/src/actors/transition.ts |  7 ++++---
 packages/core/src/setup.ts             |  3 ++-
 packages/core/src/types.ts             | 11 +++++++++--
 packages/core/test/setup.types.test.ts | 22 ++++++++++++++++++++++
 8 files changed, 69 insertions(+), 19 deletions(-)
 create mode 100644 .changeset/khaki-bees-melt.md

diff --git a/.changeset/khaki-bees-melt.md b/.changeset/khaki-bees-melt.md
new file mode 100644
index 0000000000..5ddb68acb9
--- /dev/null
+++ b/.changeset/khaki-bees-melt.md
@@ -0,0 +1,5 @@
+---
+'xstate': patch
+---
+
+Fixed an issue with contextual parameters in input factories of input-less actors
diff --git a/packages/core/src/actors/callback.ts b/packages/core/src/actors/callback.ts
index b1196f6796..3955fbe390 100644
--- a/packages/core/src/actors/callback.ts
+++ b/packages/core/src/actors/callback.ts
@@ -6,7 +6,8 @@ import {
   ActorSystem,
   ActorRefFrom,
   Snapshot,
-  AnyActorRef
+  AnyActorRef,
+  NonReducibleUnknown
 } from '../types';
 import { XSTATE_STOP } from '../constants.ts';
 
@@ -26,12 +27,12 @@ export type CallbackSnapshot<TInput> = Snapshot<undefined> & {
 
 export type CallbackActorLogic<
   TEvent extends EventObject,
-  TInput = unknown
+  TInput = NonReducibleUnknown
 > = ActorLogic<CallbackSnapshot<TInput>, TEvent, TInput, ActorSystem<any>>;
 
 export type CallbackActorRef<
   TEvent extends EventObject,
-  TInput = unknown
+  TInput = NonReducibleUnknown
 > = ActorRefFrom<CallbackActorLogic<TEvent, TInput>>;
 
 export type Receiver<TEvent extends EventObject> = (
@@ -43,7 +44,7 @@ export type Receiver<TEvent extends EventObject> = (
 export type InvokeCallback<
   TEvent extends EventObject = AnyEventObject,
   TSentEvent extends EventObject = AnyEventObject,
-  TInput = unknown
+  TInput = NonReducibleUnknown
 > = ({
   input,
   system,
@@ -132,7 +133,10 @@ export type InvokeCallback<
  * });
  * ```
  */
-export function fromCallback<TEvent extends EventObject, TInput = unknown>(
+export function fromCallback<
+  TEvent extends EventObject,
+  TInput = NonReducibleUnknown
+>(
   invokeCallback: InvokeCallback<TEvent, AnyEventObject, TInput>
 ): CallbackActorLogic<TEvent, TInput> {
   const logic: CallbackActorLogic<TEvent, TInput> = {
diff --git a/packages/core/src/actors/observable.ts b/packages/core/src/actors/observable.ts
index 7b11020d9a..148133291f 100644
--- a/packages/core/src/actors/observable.ts
+++ b/packages/core/src/actors/observable.ts
@@ -6,20 +6,27 @@ import {
   Subscription,
   AnyActorSystem,
   ActorRefFrom,
-  Snapshot
+  Snapshot,
+  NonReducibleUnknown
 } from '../types';
 
 const XSTATE_OBSERVABLE_NEXT = 'xstate.observable.next';
 const XSTATE_OBSERVABLE_ERROR = 'xstate.observable.error';
 const XSTATE_OBSERVABLE_COMPLETE = 'xstate.observable.complete';
 
-export type ObservableSnapshot<TContext, TInput> = Snapshot<undefined> & {
+export type ObservableSnapshot<
+  TContext,
+  TInput extends NonReducibleUnknown
+> = Snapshot<undefined> & {
   context: TContext | undefined;
   input: TInput | undefined;
   _subscription: Subscription | undefined;
 };
 
-export type ObservableActorLogic<TContext, TInput> = ActorLogic<
+export type ObservableActorLogic<
+  TContext,
+  TInput extends NonReducibleUnknown
+> = ActorLogic<
   ObservableSnapshot<TContext, TInput>,
   { type: string; [k: string]: unknown },
   TInput,
@@ -70,7 +77,7 @@ export type ObservableActorRef<TContext> = ActorRefFrom<
  * @see {@link https://rxjs.dev} for documentation on RxJS Observable and observable creators.
  * @see {@link Subscribable} interface in XState, which is based on and compatible with RxJS Observable.
  */
-export function fromObservable<TContext, TInput>(
+export function fromObservable<TContext, TInput extends NonReducibleUnknown>(
   observableCreator: ({
     input,
     system
@@ -214,7 +221,10 @@ export function fromObservable<TContext, TInput>(
  * canvasActor.start();
  * ```
  */
-export function fromEventObservable<T extends EventObject, TInput>(
+export function fromEventObservable<
+  T extends EventObject,
+  TInput extends NonReducibleUnknown
+>(
   lazyObservable: ({
     input,
     system
diff --git a/packages/core/src/actors/promise.ts b/packages/core/src/actors/promise.ts
index 97ebbf8ebb..cd9da973b6 100644
--- a/packages/core/src/actors/promise.ts
+++ b/packages/core/src/actors/promise.ts
@@ -1,11 +1,12 @@
+import { XSTATE_STOP } from '../constants';
 import {
   ActorLogic,
   ActorRefFrom,
   ActorSystem,
   AnyActorSystem,
+  NonReducibleUnknown,
   Snapshot
 } from '../types';
-import { XSTATE_STOP } from '../constants';
 
 export type PromiseSnapshot<TOutput, TInput> = Snapshot<TOutput> & {
   input: TInput | undefined;
@@ -82,8 +83,7 @@ export type PromiseActorRef<TOutput> = ActorRefFrom<
  * // }
  * ```
  */
-export function fromPromise<TOutput, TInput = unknown>(
-  // TODO: add types
+export function fromPromise<TOutput, TInput = NonReducibleUnknown>(
   promiseCreator: ({
     input,
     system
diff --git a/packages/core/src/actors/transition.ts b/packages/core/src/actors/transition.ts
index 63f8a7b377..fdf2877ef4 100644
--- a/packages/core/src/actors/transition.ts
+++ b/packages/core/src/actors/transition.ts
@@ -5,7 +5,8 @@ import {
   EventObject,
   ActorRefFrom,
   AnyActorSystem,
-  Snapshot
+  Snapshot,
+  NonReducibleUnknown
 } from '../types';
 
 export type TransitionSnapshot<TContext> = Snapshot<undefined> & {
@@ -15,7 +16,7 @@ export type TransitionSnapshot<TContext> = Snapshot<undefined> & {
 export type TransitionActorLogic<
   TContext,
   TEvent extends EventObject,
-  TInput
+  TInput extends NonReducibleUnknown
 > = ActorLogic<TransitionSnapshot<TContext>, TEvent, TInput, AnyActorSystem>;
 
 export type TransitionActorRef<
@@ -87,7 +88,7 @@ export function fromTransition<
   TContext,
   TEvent extends EventObject,
   TSystem extends ActorSystem<any>,
-  TInput
+  TInput extends NonReducibleUnknown
 >(
   transition: (
     state: TContext,
diff --git a/packages/core/src/setup.ts b/packages/core/src/setup.ts
index c5cd2a6995..b0b01180ea 100644
--- a/packages/core/src/setup.ts
+++ b/packages/core/src/setup.ts
@@ -19,6 +19,7 @@ import {
   SetupTypes,
   StateSchema,
   ToChildren,
+  UnknownActorLogic,
   Values
 } from './types';
 
@@ -102,7 +103,7 @@ type ToStateValue<T extends StateSchema> = T extends {
 export function setup<
   TContext extends MachineContext,
   TEvent extends AnyEventObject, // TODO: consider using a stricter `EventObject` here
-  TActors extends Record<Values<TChildrenMap>, AnyActorLogic>,
+  TActors extends Record<Values<TChildrenMap>, UnknownActorLogic>,
   TActions extends Record<string, ParameterizedObject['params'] | undefined>,
   TGuards extends Record<string, ParameterizedObject['params'] | undefined>,
   TDelay extends string,
diff --git a/packages/core/src/types.ts b/packages/core/src/types.ts
index 5013b97872..a3f8fcfa3f 100644
--- a/packages/core/src/types.ts
+++ b/packages/core/src/types.ts
@@ -2123,7 +2123,7 @@ export type Snapshot<TOutput> =
 export interface ActorLogic<
   TSnapshot extends Snapshot<unknown>,
   TEvent extends EventObject,
-  TInput = unknown,
+  TInput = NonReducibleUnknown,
   TSystem extends ActorSystem<any> = ActorSystem<any>
 > {
   /** The initial setup/configuration used to create the actor logic. */
@@ -2137,7 +2137,7 @@ export interface ActorLogic<
    * @returns The new state.
    */
   transition: (
-    state: TSnapshot,
+    snapshot: TSnapshot,
     message: TEvent,
     ctx: ActorScope<TSnapshot, TEvent, TSystem>
   ) => TSnapshot;
@@ -2184,6 +2184,13 @@ export type AnyActorLogic = ActorLogic<
   any // system
 >;
 
+export type UnknownActorLogic = ActorLogic<
+  any, // this is invariant and it's hard to figure out a better default than `any`
+  EventObject,
+  NonReducibleUnknown,
+  ActorSystem<any>
+>;
+
 export type SnapshotFrom<T> = ReturnTypeOrValue<T> extends infer R
   ? R extends ActorRef<infer _, infer TSnapshot>
     ? TSnapshot
diff --git a/packages/core/test/setup.types.test.ts b/packages/core/test/setup.types.test.ts
index 887b4b3931..f935969961 100644
--- a/packages/core/test/setup.types.test.ts
+++ b/packages/core/test/setup.types.test.ts
@@ -771,6 +771,28 @@ describe('setup()', () => {
     });
   });
 
+  it(`should provide contextual parameters to input factory for an actor that doesn't specify any input`, () => {
+    setup({
+      types: {
+        context: {} as { count: number }
+      },
+      actors: {
+        child: fromPromise(() => Promise.resolve(1))
+      }
+    }).createMachine({
+      context: { count: 1 },
+      invoke: {
+        src: 'child',
+        input: ({ context }) => {
+          // @ts-expect-error
+          context.foo;
+
+          return undefined;
+        }
+      }
+    });
+  });
+
   it('should return the correct child type on the available snapshot when the child ID for the actor was configured', () => {
     const child = createMachine({
       types: {} as {