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角度如何测试@HostListener

angular-test angular

7

Sam · 技术社区 · 8 年前

我有以下指示。当应用于输入元素时,它会检查字符,并在禁止字符时调用preventDefault:

@Directive({
 selector: '[cdtPreventInput]'
})
  export class PreventInputDirective implements OnInit {

  // the list of characters that are to be prevented
  @Input() cdtPreventInput: String;

  constructor() { }

  ngOnInit() {
    if (!this.cdtPreventInput) {
      throw new Error('cdtPreventInput cannot be used without providing a 
          list of characters.');
    }
  }

 @HostListener('keypress', ['$event']) onKeyPress(event) {
   if (_.includes(this.cdtPreventInput.split(','), event.key)) {
    event.preventDefault();
  }
}

工作正常,但我不知道如何测试它。到目前为止,我有以下几点:

describe('PreventInputDirective', () => {
  let fixture;
  let input: DebugElement;

  beforeEach(() => {
    fixture = TestBed.configureTestingModule({
      declarations: [PreventInputDirective, TestComponent]
    }).createComponent(TestComponent);

    input = fixture.debugElement.query(By.directive(PreventInputDirective));
  });

  it('should create an instance', () => {
    const directive = new PreventInputDirective();
    expect(directive).toBeTruthy();
  });

 it('should prevent default keypress event', () => {
    const event = new KeyboardEvent('keypress', {
      'key': '.'
    });
     input.nativeElement.dispatchEvent(event);

     expect(input.nativeElement.value).toEqual('');
  });

  @Component({
    template: `<input cdtPreventInput="." />`
  })
  class TestComponent { }
});

但它不起作用。不会触发按键事件。知道如何测试这个指令吗?

1 回复 | 直到 8 年前

1

14

Matias de Andrea Sam 5 年前

我找到了解决办法。我只检查事件的defaultPrevented属性,而不是检查值(它永远不会更改)。

我还遗漏了两件事:

固定装置detectChanges();在beforeach中
事件应可取消

以下是完整测试:

     describe('PreventInputDirective', () => {
      let fixture;
      let input: DebugElement;
    
      beforeEach(() => {
        fixture = TestBed.configureTestingModule({
          declarations: [PreventInputDirective, TestComponent]
        }).createComponent(TestComponent);
    
        input = fixture.debugElement.query(By.directive(PreventInputDirective));
        fixture.detectChanges();
      });
    
      it('should create an instance', () => {
        const directive = new PreventInputDirective();
        expect(directive).toBeTruthy();
      });
    
      it('should prevent keypress event', () => {
        const event = new KeyboardEvent('keypress', {
          'key': '.',
          cancelable: true
        });
    
        input.nativeElement.dispatchEvent(event);
        expect(event.defaultPrevented).toBeTruthy();
      });
    
      it('should not prevent keypress event', () => {
        const event = new KeyboardEvent('keypress', {
          'key': '5',
          cancelable: true
        });
    
        input.nativeElement.dispatchEvent(event);
        expect(event.defaultPrevented).toBeFalsy();
      });
    
      @Component({
        template: `<input cdtPreventInput="." />`
      })
      class TestComponent { }
    });