Limit inference sites for TEvent (#3131)

statelyai · Mar 7, 2022 · d9a0bcf · d9a0bcf
1 parent c66b55e
commit d9a0bcf
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diff --git a/.changeset/friendly-boxes-grow.md b/.changeset/friendly-boxes-grow.md
@@ -0,0 +1,5 @@
+---
+'xstate': patch
+---
+
+Fixed an issue with event type being inferred from too many places within `createMachine` call and possibly ending up as `any`/`AnyEventObject` for the entire machine.
diff --git a/packages/core/src/types.ts b/packages/core/src/types.ts
@@ -948,7 +948,12 @@ export interface MachineConfig<
   TAction extends BaseActionObject = BaseActionObject,
   TServiceMap extends ServiceMap = ServiceMap,
   TTypesMeta = TypegenDisabled
-> extends StateNodeConfig<NoInfer<TContext>, TStateSchema, TEvent, TAction> {
+> extends StateNodeConfig<
+    NoInfer<TContext>,
+    TStateSchema,
+    NoInfer<TEvent>,
+    TAction
+  > {
   /**
    * The initial context (extended state)
    */

diff --git a/packages/core/test/types.test.ts b/packages/core/test/types.test.ts
@@ -463,6 +463,42 @@ describe('context', () => {
   });
 });
 
+describe('events', () => {
+  it('should not use actions as possible inference sites 1', () => {
+    const machine = createMachine({
+      schema: {
+        events: {} as {
+          type: 'FOO';
+        }
+      },
+      entry: raise('FOO')
+    });
+
+    const service = interpret(machine).start();
+
+    service.send({ type: 'FOO' });
+    // @ts-expect-error
+    service.send({ type: 'UNKNOWN' });
+  });
+
+  it('should not use actions as possible inference sites 2', () => {
+    const machine = createMachine({
+      schema: {
+        events: {} as {
+          type: 'FOO';
+        }
+      },
+      entry: (_ctx, _ev: any) => {}
+    });
+
+    const service = interpret(machine).start();
+
+    service.send({ type: 'FOO' });
+    // @ts-expect-error
+    service.send({ type: 'UNKNOWN' });
+  });
+});
+
 describe('interpreter', () => {
   it('should be convertable to Rx observable', () => {
     const state$ = from(