sample.service.nobed.spec.ts

import { Observable } from 'rxjs';
import { SampleService } from './sample.service';

const mockAirports = {
  DUB: { name: 'Dublin' },
  WRO: { name: 'Wroclaw' },
  MAD: { name: 'Madrid' }
};

describe('Service: SampleService no TestBed', () => {
  let service: SampleService;
  let http = {
    get: jest.fn(() =>
      Observable.of(mockAirports)
    )
  };

  beforeEach(() => {
    service = new SampleService(http as any);
  });

  it('fetchAll$: should return a sorted list', () => {
    service.fetchAll$().subscribe((airports) => {
      expect(http.get).toBeCalledWith('https://foo.bar.com/airports');
      expect(airports.length).toBe(3);
      expect(airports[2][0]).toBe('WRO');
    });
  });

  it('fetchByIATA$: should return the selected airport', () => {
    service.fetchByIATA$('MAD').subscribe((airport) => {
      expect(http.get).toBeCalledWith('https://foo.bar.com/airports');
      expect(airport.name).toBe('Madrid');
    });
  });
});

I need to use async function in order to let tests pass.

describe('CompanyService', () => {
  it('should destruct companies key into company list', async(() => {
    const companies = [mockCompany()];
    const httpMock = { get: jest.fn(() => of({companies})) };
    const service = new CompanyService(httpMock as any);
    service.getCompanies().subscribe(data => {
      expect(httpMock.get).toHaveBeenCalledWith('/assets/data/companies.json');
      expect(data).toBe(companies);
    });
  }));
});