getFirebaseToken test on Firebase 8

getFirebaseToken.spec.ts

import firebase from 'firebase/app';
import { getFirebaseToken } from './getFirebaseToken';

describe('getFirebaseToken', () => {
  beforeAll(() => {
    jest.spyOn(firebase, 'initializeApp').mockImplementation(jest.fn());
    jest.spyOn(firebase, 'messaging').mockReturnValue({ getToken: jest.fn() });
  })

  it('should call firebase.initializeAp and firebase.messaging.getToken', async () => {
    await getFirebaseToken();

    expect(firebase.initializeApp).toHaveBeenCalled();
    expect(firebase.messaging().getToken).toHaveBeenCalled();
  });
});