testing deferred components with timer with aot: true fails

[cexbrayat]

Command

test

Is this a regression?

• Yes, this behavior used to work in the previous version

The previous version in which this bug was not present was

No response

Description

When testing a component that uses @defer (on timer(2s)), switching the tests to use AoT makes the test fails.

Minimal Reproduction

Generate a new app with latest CLI and add a component:

npx @angular/cli@20.0.0-next.9 new defer-aot-repro --defaults --no-routing
cd defer-aot-repro
ng g c user

Use app-user in app.html:

@defer (on timer(2s)) {
  <app-user />
}

Change the test to:

import { fakeAsync, TestBed, tick } from '@angular/core/testing';
import { App } from './app';

describe('App', () => {
  beforeEach(async () => {
    await TestBed.configureTestingModule({
      imports: [App],
    }).compileComponents();
  });

  it('should render user', fakeAsync(() => {
    const fixture = TestBed.createComponent(App);
    fixture.detectChanges();

    tick(2000);

    const compiled = fixture.nativeElement as HTMLElement;
    expect(compiled.querySelector('p')?.textContent).toContain('user works');
  }));
});

Run:

ng test --no-watch --code-coverage

Tests are OK 👍

Edit angular.json to add "aot": true in the test section and run:

ng test --no-watch --code-coverage

The test is failing:

Chrome Headless 135.0.0.0 (Mac OS 10.15.7) App should render user FAILED
        Expected undefined to contain 'user works'.

Exception or Error

Your Environment

Angular CLI: 20.0.0-next.9
Node: 22.14.0
Package Manager: npm 10.9.0
OS: darwin arm64

Angular: 20.0.0-next.9
... build, cli, common, compiler, compiler-cli, core, forms
... platform-browser, router

Package                      Version
------------------------------------------------------
@angular-devkit/architect    0.2000.0-next.9
@angular-devkit/core         20.0.0-next.9
@angular-devkit/schematics   20.0.0-next.9
@schematics/angular          20.0.0-next.9
rxjs                         7.8.2
typescript                   5.8.3
zone.js                      0.15.0

Anything else relevant?

No response