单元测试将类动态添加到HTML按钮茉莉花

Question

我是茉莉花的新手，并尝试学习如何在Angular4中为我的组件编写单元测试。成分。现在，当我尝试运行测试时，无法找到null的属性" classelist"。这是我到目前为止尝试的。

component.ts

ngOnInit() {
  document.querySelector('.button-visible').classList.add('hidden');
}

这是我在我的规格ts文件中尝试做的。

component.spec.ts

describe('AppComponent', () => {
 let component = AppComponent;
 let fixture: ComponentFixture<AppComponent>;
 let compiledElement;
});
beforeEach(async(() => {
 TestBed.configureTestingModule({
  declarations: [AppComponent]
  .....
}).compileComponents(); 
}));
beforeEach(() => {
 fixture = TestBed.createComponent(AppComponent);
 component = fixture.componentInstance;
 compiledElement = fixture.debugElement.nativeElement;
 fixture.detectChanges();
});
it('should create component', () => {
 expect(compiledElement.querySelector('button.button-visible').classList).toContain('hidden');
 expect(component).toBeTruthy();
});
});

我无法弄清楚如何测试。任何帮助都将不胜感激。

Answer 1

为了在需要查找其以外的组件时运行测试项目。在您的情况下，您需要一个包含具有button-visible类的DOM节点的测试组件。

您可以在测试规格中创建一个测试组件以使用：

@Component({
  template: `
    <button class="button-visible">Test Button</button>
    <app-component></app-component>
  `,
})
class TestHostComponent {
}

然后，您需要更改测试设置以包括并使用此新组件：

describe('AppComponent', () => {
  let fixture: ComponentFixture<TestHostComponent>;
  let testHostComponent: TestHostComponent;
  let component: AppComponent;
  beforeEach(async(() => {
    TestBed.configureTestingModule({
      declarations: [AppComponent, TestHostComponent]
      .....
    }).compileComponents(); 
  }));
  beforeEach(() => {
    fixture = TestBed.createComponent(TestHostComponent);
    testHostComponent = fixture.componentInstance;
    component = fixture.debugElement.query(By.directive(AppComponent)).componentInstance;
    fixture.detectChanges();
  });
});

您可以运行测试以查看测试组件中的按钮是否应用了类：

it('should add "hidden" class to HTML elements with "button-visible" class', () => {
  const buttonElement = fixture.debugElement.query(By.css('.button-visible.hidden'));
  expect(buttonElement).toBeTruthy();
});

Answer 2

我今天遇到了类似的问题编写单元测试。我想出了以下解决方案：

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

  beforeEach(async(() => {
    TestBed.configureTestingModule({
      declarations: [AppComponent]
      .....
    }).compileComponents(); 
  }));
  beforeEach(() => {
    fixture = TestBed.createComponent(AppComponent);
    component = fixture.componentInstance;
    compiledElement = fixture.debugElement.nativeElement;
    compiledElement.innerHTML += "<button class='button-visible'>Test Button</button>";
    fixture.detectChanges();
  });
  it('should create component', () => {
    expect(compiledElement.querySelector('button.button-visible').classList).toContain('hidden');
    expect(component).toBeTruthy();
  });
});