angular · atscott · May 16, 2025
diff --git a/packages/core/test/component_fixture_spec.ts b/packages/core/test/component_fixture_spec.ts
@@ -634,7 +634,7 @@ describe('ComponentFixture with zoneless', () => {
    expect(() => fixture.detectChanges()).toThrowError(/ExpressionChanged/);
  });

-  it('runs change detection when autoDetect is false', () => {
+  it('disallows autoDetect: false', () => {
    @Component({
      template: '{{thing()}}',
    })
@@ -643,9 +643,6 @@ describe('ComponentFixture with zoneless', () => {
    }

    const fixture = TestBed.createComponent(App);
-    fixture.autoDetectChanges(false);
-    fixture.componentInstance.thing.set(2);
-    fixture.detectChanges();
-    expect(fixture.nativeElement.innerText).toBe('2');
+    expect(() => fixture.autoDetectChanges(false)).toThrow();
  });
 });
diff --git a/packages/core/testing/src/component_fixture.ts b/packages/core/testing/src/component_fixture.ts
@@ -196,6 +196,9 @@ export class ComponentFixture<T> {
   */
  autoDetectChanges(): void;
  autoDetectChanges(autoDetect = true): void {
+    if (!autoDetect && this.zonelessEnabled) {
+      throw new Error('Cannot set autoDetect to false with zoneless change detection.');
+    }
    if (this._noZoneOptionIsSet && !this.zonelessEnabled) {
      throw new Error('Cannot call autoDetectChanges when ComponentFixtureNoNgZone is set.');
    }