users.service.spec.ts

  it('should get one user', inject([XHRBackend, UserService], (mockBackend: MockBackend, service: UserService) => {

    mockBackend.connections.subscribe((connection: MockConnection) => {
      mockUser = {
        name: 'John',
        age: 21
      };
      const responseOptions = new ResponseOptions({ body: JSON.stringify(mockUser) });
      connection.mockRespond(new Response(responseOptions));
      expect(connection.request.url).toBe('/users/1');
    })

    service.getOne(1).subscribe((user) => {
      expect(user).toEqual(mockUser);
    });
  }));