@Component({
  selector: 'example-test-compnent',
  template: '<div>
                  <div>{{user.name}}</div>
                  <div>{{user.fname}}</div>
                  <div>{{user.email}}</div>
             </div>'
})

export class ExampleTestComponent implements OnInit{

    let user :User = null;
    ngOnInit(): void {
       this.user.name = 'name';
       this.user.fname= 'fname';
       this.user.email= 'email';
    }
    
}

describe('Example unit test component', () => {
  let component: ExampleTestComponent ;
  let fixture: ComponentFixture<ExampleTestComponent >;

  beforeEach(async(() => {
    TestBed.configureTestingModule({
      declarations: [ExampleTestComponent]
    }).compileComponents();
  }));

  beforeEach(() => {
    fixture = TestBed.createComponent(ExampleTestComponent );
    component = fixture.componentInstance;
    fixture.detectChanges();
  });
  

  it('ngOnInit should change user object values', () => {
    expect(component.user).toBeNull(); // check that user is null on initialize
    component.ngOnInit(); // run ngOnInit

    expect(component.user.name).toEqual('name');
    expect(component.user.fname).toEqual('fname');
    expect(component.user.email).toEqual('email');
  });
});