无法在Angular 2单元测试（Jasmine）中模拟按键事件

问题描述：

我正在使用一个指令来获取用作过滤器文本的输入数据。

I am using a directive to get the data from input used as a filter text.

这是我在指令中的hostlistener：

here is my hostlistener in the directive:

@HostListener('input', ['$event.target.value'])
  public onChangeFilter(event: any): void {
    console.log('input event fired, value: ' + event);
    this.columnFiltering.filterString = event;
    this.filterChanged.emit({filtering: this.columnFiltering});
  }

此代码工作正常，我无法对其进行单元测试。

this code is working perfectly, I am unable to unit test the same.

我已经订阅了filterChanged EventEmitter，在我的单元测试中检查了值。

I have subscribed to the filterChanged EventEmitter, in my unit test to check the value.

我尝试模拟按键事件来更改值并尝试设置值属性。这些都不适合我。

I tried simulating keypress event to change value and also tried settings value attribute. None of these is working for me.

这是我的spec文件：

here is my spec file:

describe('Table View', () => {
  let fixture: ComponentFixture<any>;
    let context: TableComponent;
   beforeEach(() => {
     TestBed.configureTestingModule({
          providers: [
            TableComponent,
          ],
          imports: [TableModule],
      });
      fixture = TestBed.createComponent(TableComponent);
      context = fixture.componentInstance;
    });
it('should allow filter', () => {
      const element = fixture.nativeElement;
      context.config = config;
      fixture.detectChanges();

      let tableChangeCount = 0;
      let tableEvent: any;
      context.tableChanged.subscribe((event: any) => {
        tableChangeCount++;
        tableEvent = event;
      });
      // Check if table exists
      let inputElement = element.querySelectorAll('tr')[1].querySelector('input');
    let e = new KeyboardEvent("keypress", {
            key: "a",
            bubbles: true,
            cancelable: true,
          });
          inputElement.dispatchEvent(e);
 });

});

我尝试设定价值：

let attrs = inputElement.attributes;
      inputElement.setAttribute('value', 'abc');
       for (let i = attrs.length - 1; i >= 0; i--) {
         // Attribute value is set correctly
         if (attrs[i].name === 'value') {
         console.log(attrs[i].name + "->" + attrs[i].value);
         }
       }

任何人都可以帮助我，我该如何进行单元测试同样的？

Can anyone please help me, how can I unit test the same?

答

我在单元测试中模拟按键时遇到了一些麻烦。但是Seyed Jalal Hosseini发现了一个答案。它可能就是您所追求的。

I've had some trouble simulating a keypress in a unit test also. But came across an answer by Seyed Jalal Hosseini. It might be what you're after.

如果您正在尝试模拟按键，则可以通过调用 dispatchEvent（新事件）来触发事件（'keypress'））; 关于元素。

If you're attempting to simulate a keypress you can trigger an event by calling dispatchEvent(new Event('keypress')); on the element.

这是我所指的答案，它提供了更多细节： https://stackoverflow.com/a/37956877/4081730

Here is the answer I'm referring to which gives more detail : https://stackoverflow.com/a/37956877/4081730

如果你想设置按下的键，也可以这样做。

If you want to set the key that was pressed, this can be done also.

const event = new KeyboardEvent("keypress",{
    "key": "Enter"
});
el.dispatchEvent(event);

Further information I've just come across: https://developer.mozilla.org/en-US/docs/Web/Guide/Events/Creating_and_triggering_events

无法在Angular 2单元测试（Jasmine）中模拟按键事件

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