Question

我在ngOnInit函数内部有一个带有setTimeOut函数的组件。为此，我要使用tick和fakeAsync来编写单元测试用例，以快速转发setTimeOut。但是，它没有被执行，因此又没有调用其他函数closeAlert（）。

组件代码：

export class BannerComponent implements OnInit {

  @Input()errorData: any;

  @Input()callback: any;

  @Input()autoHide: boolean;

  constructor() { }

  ngOnInit() {

    if (this.autoHide) {
      setTimeout
        (() => {
          this.closeAlert();
        }, 500);
    }
  }

  closeAlert() {
    this.errorData = null;
    if (this.callback) {
      this.callback();
    }
  };
}

规范文件：

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

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

  beforeEach(async() => {
    fixture = TestBed.createComponent(BannerComponent);
    component = fixture.componentInstance;
    component.ngOnInit();
    fixture.detectChanges();
  });

  it("banner should hide after 500ms", fakeAsync(() => {
    component.errorData = {
      _statusMessage: "New alert banner",
      _statusCode: '200',
    };
    component.callback = null;;
    component.autoHide = true;

    tick(600);
    fixture.detectChanges()

    fixture.whenStable().then(() => {
      let banner = fixture.debugElement.query(By.css('.success'));
      expect(banner).toBe(null)
    })
  }));

});

HTML代码：

<div class="success">
    <p>{{errorData._statusMessage}}</p>
</div>

Answer 1

我在代码中看到了几个问题。

在component.ngOnInit()中设置有效数据之前，您要同时调用fixture.detectChanges()和component.errorData（也将调用ngOnInit）。
我不清楚您为什么期望banner与显示的html为空。因此，我将测试更改为看到component.closeAlert()被调用，并且如果component.errorData被重置为null，因为看来这是您真正想要测试的东西。为了测试这一点，我在component.closeAlert()上进行了监视。
我通过在component.closeAlert()之后进行测试，然后在又一个滴答之后进行测试，来设置滴答声以准确显示何时向tick(499)发出呼叫。

工作StackBlitz。

代码：

beforeEach(async(() => { // slight correction of incorrect async wrapper ...
  fixture = TestBed.createComponent(BannerComponent);
  component = fixture.componentInstance;
  // component.ngOnInit(); // <-- don't call this here, the data isn't set up yet ...
  // fixture.detectChanges(); // ditto
}));

it("banner should hide after 500ms", fakeAsync(() => {
  spyOn(component, 'closeAlert').and.callThrough(); // set up a spy so we can test later
  component.errorData = {
    _statusMessage: "New alert banner",
    _statusCode: '200',
  };
  component.callback = null;;
  component.autoHide = true;

  fixture.detectChanges(); // <-- this will execute ngOnInit()
  expect(component.errorData).not.toBeNull(); // <-- after ngOnInit, still NOT null
  expect(component.closeAlert).not.toHaveBeenCalled();
  tick(499); // <-- now let 499ms pass ...
  expect(component.errorData).not.toBeNull(); // <-- after all that "fake" time, still NOT null
  expect(component.closeAlert).not.toHaveBeenCalled();
  tick(1); // <-- now tick for just 1 more millisecond ...
  expect(component.errorData).toBeNull(); // <-- now this has become NULL
  expect(component.closeAlert).toHaveBeenCalled(); // <-- and the method was called
  // fixture.whenStable().then(() => {
  //   let banner = fixture.debugElement.query(By.css('.success'));
  //   expect(banner).toBe(null)
  // });
}));

我希望这会有所帮助！

带有setTimeOut的Angular 6单元测试ngOnInit不起作用

1 个答案: