使用 debounce 测试 angular 指令

Question

我为我的搜索字段写了一个去抖动指令以防止后端过多calls/processing。它按预期工作。但是我无法为它编写规范。我希望你们中的一些人能帮助我 :) 如果你想尝试一下，我创建了一个 plunker here。目前我认为指令未按预期初始化。

我的指令

import { NgModel } from '@angular/forms';
import { fromEvent } from 'rxjs';
import { debounceTime, map } from 'rxjs/operators';

@Directive({selector: '[debounce]'})
export class DebounceDirective implements OnInit {
  @Input() delay: number = 300;

  constructor(private elementRef: ElementRef, private model: NgModel) {
  }

  public ngOnInit(): void {
    const eventStream = fromEvent(this.elementRef.nativeElement, 'keyup').pipe(
      map(() => {
        return this.model.value;
      }),
      debounceTime(this.delay));

    this.model.viewToModelUpdate = () => {
    };

    eventStream.subscribe(input => {
      this.model.viewModel = input;
      this.model.update.emit(input);
    });
  }
}

我的规格

import { DebounceDirective } from '@modules/shared/directives/debounce.directive';
import { ComponentFixture, fakeAsync, TestBed, tick } from '@angular/core/testing';
import { Component, DebugElement, ViewChild } from '@angular/core';
import { By } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';

@Component({
  template: '<input type="text" name="test" debounce [delay]="500" [(ngModel)]="value" (ngModelChange)="test()">'
})
class DebounceDirectiveTestingComponent {
  @ViewChild(DebounceDirective) directive: DebounceDirective;
  public value: string = '';

  public test() {
  }
}

describe('Directive: Debounce', () => {
  let component: DebounceDirectiveTestingComponent;
  let fixture: ComponentFixture<DebounceDirectiveTestingComponent>;
  let inputEl: DebugElement;

  beforeEach(() => {
    TestBed.configureTestingModule({
      imports: [FormsModule],
      declarations: [DebounceDirective, DebounceDirectiveTestingComponent]
    }).compileComponents();
  });

  beforeEach(() => {
    fixture = TestBed.createComponent(DebounceDirectiveTestingComponent);
    component = fixture.componentInstance;
    inputEl = fixture.debugElement.query(By.css('input'));
    fixture.detectChanges();
  });

  it('should create component', () => {
    expect(component).toBeTruthy();
  });

  it('should emit values after 500 msec debounce', fakeAsync(() => {
    const directiveEl = fixture.debugElement.query(By.directive(DebounceDirective));
    spyOn(component, 'test').and.stub();
    spyOn(component.directive, 'ngOnInit').and.callThrough();

    fixture.detectChanges();

    expect(directiveEl).toBeDefined();
    expect(component.directive.ngOnInit).toHaveBeenCalled();
    expect(component.directive.delay).toBe(500);

    inputEl.nativeElement.value = 'test';
    inputEl.nativeElement.dispatchEvent(new Event('keyup'));

    fixture.detectChanges();

    expect(component.value).toBe('');

    tick(500);
    fixture.detectChanges();

    expect(component.test).toHaveBeenCalled();
    expect(component.value).toBe('test');
  }));
});

Answer 1

按照@trollr 的建议，我发布了作为答案的解决方案：将事件类型从 'keyup' 事件更改为 'input' 事件。

在指令中：

const eventStream = fromEvent(this.elementRef.nativeElement, 'input').pipe(

并且在测试中：

inputEl.nativeElement.dispatchEvent(new Event('input'));

这些更改以及注释掉对 fixture.detectChanges() 的第一次调用已经解决了这个问题。

这里 StackBlitz 显示所有测试都通过了。

使用 debounce 测试 angular 指令

Testing angular directive with debounce

unit-testing

jasmine

karma-jasmine

angular-directive

angular