测试来自 Angular 属性指令的点击

Question

我在为我编写的 Angular 属性指令创建单元测试时遇到问题。该指令称为TrackClickDirective，我正在尝试测试以下内容。

• 当单击附加了此指令的元素时，它应该调用该指令的特定方法。

我怀疑这是我的单元测试配置有问题。

请参阅我在 StackBlitz 上的实现，您可以在其中看到测试正在运行：

StackBlitz： https ://stackblitz.com/edit/angular-test-click-on-attribute-directive-with-hostlistener

这是我的单元测试代码 - track-click.directive.spec.ts：

import { Component, ElementRef, DebugElement } from '@angular/core';
import { ComponentFixture, TestBed } from '@angular/core/testing';
import { By } from "@angular/platform-browser";
import { TrackClickDirective } from './track-click.directive';
import { Analytics} from './analytics.service';

class MockAnalytics {
  eventTrack() {}
};
class MockElementRef {
}

@Component({
  template: '<button appTrackClick>Test</button>'
})
export class TestButtonWithoutNameComponent { }

describe('TrackClickDirective', () => {

  let component: TestButtonWithoutNameComponent;
  let fixture: ComponentFixture<TestButtonWithoutNameComponent>;
  let directive: TrackClickDirective;
  let inputEl: DebugElement;
  let spy: any;

  beforeEach(() => {
    TestBed.configureTestingModule({
      declarations: [
        TestButtonWithoutNameComponent
      ],
      providers: [
        TrackClickDirective,
        { provide: Analytics, useClass: MockAnalytics },
        { provide: ElementRef, useClass: MockElementRef }
      ]
    });
    fixture = TestBed.createComponent(TestButtonWithoutNameComponent);
    component = fixture.componentInstance;
    directive = TestBed.get(TrackClickDirective);
    inputEl = fixture.debugElement.query(By.css('button'));
  });

  it('should call the trackClick methoe when the button is clicked', () => {
    spy = spyOn(directive, 'trackClick');
    inputEl.triggerEventHandler('click', null);
    fixture.detectChanges();
    expect(directive.trackClick).toHaveBeenCalled();
  });
});

我在这里做错了什么？当我运行单元测试时，我得到以下信息：

FAILED TESTS:
  TrackClickDirective
    ? should call the trackClick method when the button is clicked
      HeadlessChrome 72.0.3626 (Mac OS X 10.14.0)
    Expected spy trackClick to have been called.

Answer 1

遵循Angular's docs上的示例。

以下应该可以解决问题：

import { Component, ElementRef, DebugElement } from '@angular/core';
import { ComponentFixture, TestBed } from '@angular/core/testing';
import { By } from "@angular/platform-browser";
import { TrackClickDirective } from './track-click.directive';
import { Analytics} from './analytics.service';

class MockAnalytics {
  eventTrack() {}
};
class MockElementRef {
}

@Component({
  template: '<button appTrackClick>Test</button>'
})
export class TestButtonWithoutNameComponent { }

describe('TrackClickDirective', () => {

  let component: TestButtonWithoutNameComponent;
  let fixture: ComponentFixture<TestButtonWithoutNameComponent>;
  let directive: TrackClickDirective;
  let inputEl: DebugElement;
  let spy: any;

  beforeEach(() => {
    TestBed.configureTestingModule({
      declarations: [
        TestButtonWithoutNameComponent,
        TrackClickDirective
      ],
      providers: [
        TrackClickDirective,
        { provide: Analytics, useClass: MockAnalytics },
        { provide: ElementRef, useClass: MockElementRef }
      ]
    });
    fixture = TestBed.createComponent(TestButtonWithoutNameComponent);
    component = fixture.componentInstance;
    directive = TestBed.get(TrackClickDirective);
    inputEl = fixture.debugElement.query(By.css('button'));
  });

  it('should call the trackClick method when the button is clicked', () => {
    directive = fixture.debugElement.query(By.directive(TrackClickDirective)).injector.get(TrackClickDirective) as TrackClickDirective;
    spy = spyOn(directive, 'trackClick');
    inputEl.triggerEventHandler('click', null);
    fixture.detectChanges();
    expect(directive.trackClick).toHaveBeenCalled();
  });
});

关键在这一行：

fixture.debugElement.query(By.directive(TrackClickDirective)).injector.get(TrackClickDirective) as TrackClickDirective;

虽然非常冗长，但它允许您获取已创建并在组件中使用的指令的实际实例，进而允许您监视其方法。

更新的 StackBlitz 示例： https ://stackblitz.com/edit/angular-test-click-on-attribute-directive-with-hostlistener