"Expected to be running in 'ProxyZone', but it was not found." with jest

I am migrating an Angular workspace with Karma to an Nx workspace with Jest. I'm having a couple of issues, one of them being the use fakeAsync, which results in the following error:

Expected to be running in 'ProxyZone', but it was not found.

I had to do a bunch of shenanigans to make jest work at all because my app uses @ionic and @ionic-native. I thought the issue was related to said-shenanigans, but I managed to make a kind-of-minimal repro here. Here are the important stuff:

Here is my jest.preset.js.

const nxPreset = require('@nrwl/jest/preset');
module.exports = {
  ...nxPreset,
  testMatch: ['**/+(*.)+(spec|test).+(ts|js)?(x)'],
  transform: {
    '^.+\\.(ts|js|html)$': 'ts-jest',
  },
  testEnvironment: 'jest-environment-jsdom-fourteen',
  resolver: '@nrwl/jest/plugins/resolver',
  moduleFileExtensions: ['ts', 'js', 'html'],
  coverageReporters: ['html'],
};

Here is my jest.config.js.

module.exports = {
  preset: '../../jest.preset.js',
  coverageDirectory: '../../coverage/apps/products',
  snapshotSerializers: [
    'jest-preset-angular/build/AngularNoNgAttributesSnapshotSerializer.js',
    'jest-preset-angular/build/AngularSnapshotSerializer.js',
    'jest-preset-angular/build/HTMLCommentSerializer.js',
  ],
  setupFilesAfterEnv: ['<rootDir>/src/test-setup.ts'],
  globals: {
    'ts-jest': {
      tsConfig: '<rootDir>/tsconfig.spec.json',
      stringifyContentPathRegex: '\\.(html|svg)$',
      astTransformers: {
        before: [
          'jest-preset-angular/build/InlineFilesTransformer',
          'jest-preset-angular/build/StripStylesTransformer',
        ],
      },
    },
  },
  displayName: 'products',
};

Finally, here is my test file.

describe('AppComponent', () => {
  let fixture: ComponentFixture<AppComponent>;

  beforeEach(async(() => {
    TestBed.configureTestingModule({
      imports: [RouterTestingModule],
      declarations: [AppComponent],
      schemas: [CUSTOM_ELEMENTS_SCHEMA]
    }).compileComponents();
    fixture = TestBed.createComponent(AppComponent);

    fixture.detectChanges();
  }));

  // This test gives me an error.
  it('should create the app', fakeAsync(() => {
    const app = fixture.debugElement.componentInstance;
    expect(app).toBeTruthy();
  }));

  // This test passes.
  it(`should render the header`, () => {
    expect(
      fixture.nativeElement.querySelector('nx-example-header')
    ).toBeTruthy();
  });
});

Finally, here is the test-setup.ts.

import 'jest-preset-angular';
import 'document-register-element';
import 'zone.js/dist/zone-testing';

This setup seems pretty vanilla to me, I'm not sure on which side the issue is (nx, jest, jest-preset-angular?).

Thanks for your help!

I managed to fix this by removing the import 'zone.js/dist/zone-testing'; line from my test-setup.ts file. I'm not sure why this fixed it. I know that jest-preset-angular patches describe/test functions so that they work within Zone.js. I guess zone.js/dist/zone-testing was overriding the patch or something.