Angular 6 单元测试 ngOnInit 与 setTimeOut 不工作

Question

我在 ngOnInit 函数中有一个带有 setTimeOut 函数的组件。为了为此编写单元测试用例，我使用 tick 和 fakeAsync 来快进 setTimeOut。但是，它没有被执行，这反过来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();
    }
  };
}

规格文件：

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

我在代码中发现了几个问题。

在 component.errorData.

component.ngOnInit()

fixture.detectChanges()

我不清楚为什么您期望 banner 与您显示的 html 为空。因此，我将测试更改为查看 component.closeAlert() 是否已被调用，并且 component.errorData 是否已重置为 null，因为看起来这才是您真正想要测试的。为了对此进行测试，我监视了 component.closeAlert().
我通过在 tick(499) 之后进行测试来设置滴答以准确显示调用 component.closeAlert() 的时间，然后再进行一次滴答...

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)
  // });
}));

希望对您有所帮助！

Angular 6 单元测试 ngOnInit 与 setTimeOut 不工作

Angular 6 Unit Test ngOnInit with a setTimeOut not working

unit-testing

angular

angular-unit-test

angular5

angular6