Fix #5448: Bug: [5.25.0] typing issue when using assertEvent and generi

Author: Your Name

packages/core/src/assert.ts

@@ -26,7 +26,7 @@ import { matchesEventDescriptor, toArray } from './utils.ts';
  */
 export function assertEvent<
   TEvent extends EventObject,
-  TAssertedDescriptor extends EventDescriptor<TEvent>
+  TAssertedDescriptor extends string = string
 >(
   event: TEvent,
   type: TAssertedDescriptor | readonly TAssertedDescriptor[]

packages/core/test/assert.test.ts

@@ -1,4 +1,4 @@
-import { createActor, createMachine, assertEvent } from '../src';
+import { createActor, createMachine, assertEvent, InspectionEvent } from '../src';
 
 describe('assertion helpers', () => {
   it('assertEvent asserts the correct event type', () => {
@@ -103,4 +103,23 @@ describe('assertion helpers', () => {
 
     return promise;
   });
+
+  it('assertEvent works with generics', () => {
+    // Test with InspectionEvent and generic type parameter
+    function test<TEVENT extends InspectionEvent>(event: TEVENT) {
+      assertEvent(event, '@xstate.event');
+      event.event satisfies any;
+    }
+
+    // This should compile without errors
+    const mockEvent: InspectionEvent = {
+      type: '@xstate.event',
+      rootId: 'root',
+      actorRef: { id: '1' } as any,
+      sourceRef: undefined,
+      event: { type: 'test' }
+    };
+
+    expect(() => test(mockEvent as any)).not.toThrow();
+  });
 });

packages/core/test/assert.types.test.ts

@@ -0,0 +1,35 @@
+import { assertEvent, InspectionEvent } from '../src/index';
+
+describe('assertEvent type tests', () => {
+  it('should work with non-generic event types', () => {
+    function test(event: InspectionEvent) {
+      assertEvent(event, '@xstate.event');
+      event.event satisfies any;
+    }
+  });
+
+  it('should work with generic event types', () => {
+    function test<TEVENT extends InspectionEvent>(event: TEVENT) {
+      assertEvent(event, '@xstate.event');
+      event.event satisfies any;
+    }
+  });
+
+  it('should work with generic event types and multiple descriptors', () => {
+    function test<TEVENT extends InspectionEvent>(event: TEVENT) {
+      assertEvent(event, ['@xstate.event', '@xstate.snapshot']);
+      event.event satisfies any;
+    }
+  });
+
+  it('should properly narrow types after assertion', () => {
+    type MyEvent = { type: 'foo'; value: string } | { type: 'bar'; count: number };
+
+    function test<T extends MyEvent>(event: T) {
+      assertEvent(event, 'foo');
+      event.value satisfies string;
+      // @ts-expect-error
+      event.count;
+    }
+  });
+});

test_generics.ts

@@ -0,0 +1,11 @@
+import { InspectionEvent, assertEvent } from './packages/core/src/index.ts';
+
+function test(event: InspectionEvent) {
+  assertEvent(event, '@xstate.event');
+  console.log(event.event);
+}
+
+function test2<TEVENT extends InspectionEvent>(event: TEVENT) {
+  assertEvent(event, '@xstate.event');
+  console.log(event.event);
+}