Fixed ContextFrom and EventFrom types (#3104)

statelyai · Mar 2, 2022 · 3706c62 · 3706c62
1 parent ae20405
commit 3706c62
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diff --git a/.changeset/good-queens-cross.md b/.changeset/good-queens-cross.md
@@ -0,0 +1,5 @@
+---
+'xstate': patch
+---
+
+Fixed `ContextFrom` helper type to work on typegened machines.
diff --git a/.changeset/wet-insects-share.md b/.changeset/wet-insects-share.md
@@ -0,0 +1,5 @@
+---
+'xstate': patch
+---
+
+Fixed `EventFrom` helper type to work on machines.
diff --git a/packages/core/src/types.ts b/packages/core/src/types.ts
@@ -1783,13 +1783,27 @@ export type EmittedFrom<T> = ReturnTypeOrValue<T> extends infer R
   : never;
 
 type ResolveEventType<T> = ReturnTypeOrValue<T> extends infer R
-  ? R extends StateMachine<infer _, infer __, infer TEvent, infer ____>
+  ? R extends StateMachine<
+      infer _,
+      infer __,
+      infer TEvent,
+      infer ___,
+      infer ____,
+      infer _____,
+      infer ______
+    >
     ? TEvent
-    : R extends Model<infer _, infer TEvent, infer ___, infer ____>
+    : R extends Model<infer _, infer TEvent, infer __, infer ___>
     ? TEvent
-    : R extends State<infer _, infer TEvent, infer ___, infer ____>
+    : R extends State<infer _, infer TEvent, infer __, infer ___, infer ____>
     ? TEvent
-    : R extends Interpreter<infer _, infer __, infer TEvent, infer ____>
+    : R extends Interpreter<
+        infer _,
+        infer __,
+        infer TEvent,
+        infer ___,
+        infer ____
+      >
     ? TEvent
     : R extends ActorRef<infer TEvent, infer _>
     ? TEvent
@@ -1803,13 +1817,27 @@ export type EventFrom<
 > = IsNever<K> extends true ? TEvent : Extract<TEvent, { type: K }>;
 
 export type ContextFrom<T> = ReturnTypeOrValue<T> extends infer R
-  ? R extends StateMachine<infer TContext, infer _, infer __, infer ___>
+  ? R extends StateMachine<
+      infer TContext,
+      infer _,
+      infer __,
+      infer ___,
+      infer ____,
+      infer _____,
+      infer ______
+    >
     ? TContext
     : R extends Model<infer TContext, infer _, infer __, infer ___>
     ? TContext
-    : R extends State<infer TContext, infer _, infer __, infer ___>
+    : R extends State<infer TContext, infer _, infer __, infer ___, infer ____>
     ? TContext
-    : R extends Interpreter<infer TContext, infer _, infer __, infer ___>
+    : R extends Interpreter<
+        infer TContext,
+        infer _,
+        infer __,
+        infer ___,
+        infer ____
+      >
     ? TContext
     : never
   : never;
diff --git a/packages/core/test/typeHelpers.test.ts b/packages/core/test/typeHelpers.test.ts
@@ -1,8 +1,108 @@
-import { assign, createMachine, EventFrom, MachineOptionsFrom } from '../src';
+import {
+  assign,
+  ContextFrom,
+  createMachine,
+  EventFrom,
+  MachineOptionsFrom
+} from '../src';
 import { createModel } from '../src/model';
 import { TypegenMeta } from '../src/typegenTypes';
 
+describe('ContextFrom', () => {
+  it('should return context of a machine', () => {
+    const machine = createMachine({
+      schema: {
+        context: {} as { counter: number }
+      }
+    });
+
+    type MachineContext = ContextFrom<typeof machine>;
+
+    const acceptMachineContext = (_event: MachineContext) => {};
+
+    acceptMachineContext({ counter: 100 });
+    acceptMachineContext({
+      counter: 100,
+      // @ts-expect-error
+      other: 'unknown'
+    });
+    const obj = { completely: 'invalid' };
+    // @ts-expect-error
+    acceptMachineContext(obj);
+  });
+
+  it('should return context of a typegened machine', () => {
+    const machine = createMachine({
+      tsTypes: {} as TypegenMeta,
+      schema: {
+        context: {} as { counter: number }
+      }
+    });
+
+    type MachineContext = ContextFrom<typeof machine>;
+
+    const acceptMachineContext = (_event: MachineContext) => {};
+
+    acceptMachineContext({ counter: 100 });
+    acceptMachineContext({
+      counter: 100,
+      // @ts-expect-error
+      other: 'unknown'
+    });
+    const obj = { completely: 'invalid' };
+    // @ts-expect-error
+    acceptMachineContext(obj);
+  });
+});
+
 describe('EventFrom', () => {
+  it('should return events for a machine', () => {
+    const machine = createMachine({
+      schema: {
+        events: {} as
+          | { type: 'UPDATE_NAME'; value: string }
+          | { type: 'UPDATE_AGE'; value: number }
+          | { type: 'ANOTHER_EVENT' }
+      }
+    });
+
+    type MachineEvent = EventFrom<typeof machine>;
+
+    const acceptMachineEvent = (_event: MachineEvent) => {};
+
+    acceptMachineEvent({ type: 'UPDATE_NAME', value: 'test' });
+    acceptMachineEvent({ type: 'UPDATE_AGE', value: 12 });
+    acceptMachineEvent({ type: 'ANOTHER_EVENT' });
+    acceptMachineEvent({
+      // @ts-expect-error
+      type: 'UNKNOWN_EVENT'
+    });
+  });
+
+  it('should return events for a typegened machine', () => {
+    const machine = createMachine({
+      tsTypes: {} as TypegenMeta,
+      schema: {
+        events: {} as
+          | { type: 'UPDATE_NAME'; value: string }
+          | { type: 'UPDATE_AGE'; value: number }
+          | { type: 'ANOTHER_EVENT' }
+      }
+    });
+
+    type MachineEvent = EventFrom<typeof machine>;
+
+    const acceptMachineEvent = (_event: MachineEvent) => {};
+
+    acceptMachineEvent({ type: 'UPDATE_NAME', value: 'test' });
+    acceptMachineEvent({ type: 'UPDATE_AGE', value: 12 });
+    acceptMachineEvent({ type: 'ANOTHER_EVENT' });
+    acceptMachineEvent({
+      // @ts-expect-error
+      type: 'UNKNOWN_EVENT'
+    });
+  });
+
   it('should return events for createModel', () => {
     const userModel = createModel(
       {},