Fixed inference for assign using PropertyAssigner (#3818)

* Fixed inference for `assign` using `PropertyAssigner` * fixed types in tests * Deduplicate TS version * Create tough-lizards-begin.md
statelyai · Feb 9, 2023 · 2d8d84f · 2d8d84f
1 parent 5108c25
commit 2d8d84f
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diff --git a/.changeset/tough-lizards-begin.md b/.changeset/tough-lizards-begin.md
@@ -0,0 +1,11 @@
+---
+"xstate": patch
+---
+
+Fixed inference for `assign` using `PropertyAssigner`, like here:
+```ts
+actions: assign({
+  counter: 0,
+  delta: (ctx, ev) => ev.delta,
+})
+```
diff --git a/packages/core/src/actions.ts b/packages/core/src/actions.ts
@@ -41,7 +41,8 @@ import {
   EventFrom,
   AnyActorRef,
   PredictableActionArgumentsExec,
-  BaseActionObject
+  BaseActionObject,
+  LowInfer
 } from './types';
 import * as actionTypes from './actionTypes';
 import {
@@ -467,7 +468,9 @@ export function resolveStop<TContext, TEvent extends EventObject>(
  * @param assignment An object that represents the partial context to update.
  */
 export const assign = <TContext, TEvent extends EventObject = EventObject>(
-  assignment: Assigner<TContext, TEvent> | PropertyAssigner<TContext, TEvent>
+  assignment:
+    | Assigner<LowInfer<TContext>, TEvent>
+    | PropertyAssigner<LowInfer<TContext>, TEvent>
 ): AssignAction<TContext, TEvent> => {
   return {
     type: actionTypes.assign,

diff --git a/packages/core/test/types.test.ts b/packages/core/test/types.test.ts
@@ -889,4 +889,45 @@ describe('actions', () => {
       ]
     });
   });
+
+  it('should accept assign with partial static object', () => {
+    createMachine({
+      schema: {
+        events: {} as {
+          type: 'TOGGLE';
+        },
+        context: {} as {
+          count: number;
+          mode: 'foo' | 'bar' | null;
+        }
+      },
+      context: {
+        count: 0,
+        mode: null
+      },
+      entry: assign({ mode: 'foo' })
+    });
+  });
+
+  it("should provide context to single prop updater in assign when it's mixed with a static value for another prop", () => {
+    createMachine({
+      schema: {
+        context: {} as {
+          count: number;
+          skip: boolean;
+        },
+        events: {} as {
+          type: 'TOGGLE';
+        }
+      },
+      context: {
+        count: 0,
+        skip: true
+      },
+      entry: assign({
+        count: (context) => context.count + 1,
+        skip: true
+      })
+    });
+  });
 });
diff --git a/packages/xstate-react/test/useSelector.test.tsx b/packages/xstate-react/test/useSelector.test.tsx
@@ -1,6 +1,7 @@
 import { act, fireEvent, screen } from '@testing-library/react';
 import * as React from 'react';
 import {
+  ActorRef,
   ActorRefFrom,
   AnyState,
   assign,
@@ -294,7 +295,7 @@ describeEachReactMode('useSelector (%s)', ({ suiteKey, render }) => {
     const parentMachine = createMachine({
       schema: {
         context: {} as {
-          childActor: ActorRefFrom<ReturnType<typeof createActor>>;
+          childActor: ActorRef<any, any>;
         }
       },
       entry: assign({
@@ -303,8 +304,8 @@ describeEachReactMode('useSelector (%s)', ({ suiteKey, render }) => {
     });
 
     const identitySelector = (value: any) => value;
-    const getSnapshot = (actor: ReturnType<typeof createActor>) =>
-      actor.latestValue;
+    const getSnapshot = (actor: ActorRef<any, any>) =>
+      (actor as any).latestValue;
 
     const App = () => {
       const [state] = useMachine(parentMachine);
@@ -433,7 +434,7 @@ describeEachReactMode('useSelector (%s)', ({ suiteKey, render }) => {
     const parentMachine = createMachine({
       schema: {
         context: {} as {
-          childActor: ActorRefFrom<ReturnType<typeof createActor>>;
+          childActor: ActorRef<any, any>;
         }
       },
       entry: assign({
@@ -442,8 +443,8 @@ describeEachReactMode('useSelector (%s)', ({ suiteKey, render }) => {
     });
 
     const identitySelector = (value: any) => value;
-    const getSnapshot = (actor: ReturnType<typeof createActor>) =>
-      actor.latestValue;
+    const getSnapshot = (actor: ActorRef<any, any>) =>
+      (actor as any).latestValue;
 
     const App = () => {
       const [state] = useMachine(parentMachine);

diff --git a/yarn.lock b/yarn.lock
@@ -9464,12 +9464,7 @@ typedarray@^0.0.6:
   resolved "https://registry.yarnpkg.com/typedarray/-/typedarray-0.0.6.tgz#867ac74e3864187b1d3d47d996a78ec5c8830777"
   integrity sha1-hnrHTjhkGHsdPUfZlqeOxciDB3c=
 
-typescript@*:
-  version "4.5.5"
-  resolved "https://registry.yarnpkg.com/typescript/-/typescript-4.5.5.tgz#d8c953832d28924a9e3d37c73d729c846c5896f3"
-  integrity sha512-TCTIul70LyWe6IJWT8QSYeA54WQe8EjQFU4wY52Fasj5UKx88LNYKCgBEHcOMOrFF1rKGbD8v/xcNWVUq9SymA==
-
-typescript@^4.8.4:
+typescript@*, typescript@^4.8.4:
   version "4.8.4"
   resolved "https://registry.yarnpkg.com/typescript/-/typescript-4.8.4.tgz#c464abca159669597be5f96b8943500b238e60e6"
   integrity sha512-QCh+85mCy+h0IGff8r5XWzOVSbBO+KfeYrMQh7NJ58QujwcE22u+NUSmUxqF+un70P9GXKxa2HCNiTTMJknyjQ==