使用@Input()进行Angular2单元测试

Question

我有一个@Input()在实例变量上使用注释的组件,我正在尝试为该openProductPage()方法编写单元测试,但是我在设置单元测试方面有点迷失.我可以将该实例变量公之于众,但我认为我不应该诉诸于此.

如何设置我的Jasmine测试以便注入模拟产品(提供？)并且我可以测试该openProductPage()方法？

我的组件:

import {Component, Input} from "angular2/core";
import {Router} from "angular2/router";

import {Product} from "../models/Product";

@Component({
    selector: "product-thumbnail",
    templateUrl: "app/components/product-thumbnail/product-thumbnail.html"
})

export class ProductThumbnail {
    @Input() private product: Product;


    constructor(private router: Router) {
    }

    public openProductPage() {
        let id: string = this.product.id;
        this.router.navigate([“ProductPage”, {id: id}]);
    }
}

Answer 1

如果您使用TestBed.configureTestingModule编译测试组件,这是另一种方法.它与接受的答案基本相同,但可能更类似于angular-cli生成规范的方式.FWIW.

import { Component, CUSTOM_ELEMENTS_SCHEMA } from '@angular/core';
import { async, ComponentFixture, TestBed } from '@angular/core/testing';
import { DebugElement } from '@angular/core';

describe('ProductThumbnail', () => {
  let component: ProductThumbnail;
  let fixture: ComponentFixture<TestComponentWrapper>;

  beforeEach(async(() => {
    TestBed.configureTestingModule({
      declarations: [ 
        TestComponentWrapper,
        ProductThumbnail
      ],
      schemas: [CUSTOM_ELEMENTS_SCHEMA]
    })
    .compileComponents();

    fixture = TestBed.createComponent(TestComponentWrapper);
    component = fixture.debugElement.children[0].componentInstance;
    fixture.detectChanges();
  });

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

@Component({
  selector: 'test-component-wrapper',
  template: '<product-thumbnail [product]="product"></product-thumbnail>'
})
class TestComponentWrapper {
  product = new Product()
}

Answer 2

这是来自官方文档https://angular.io/docs/ts/latest/guide/testing.html#!#component-fixture.因此,您可以创建新的输入对象expectedHero并将其传递给组件comp.hero = expectedHero

还要确保调用fixture.detectChanges();last,否则属性不会绑定到组件.

工作实例

// async beforeEach
beforeEach( async(() => {
    TestBed.configureTestingModule({
        declarations: [ DashboardHeroComponent ],
    })
    .compileComponents(); // compile template and css
}));

// synchronous beforeEach
beforeEach(() => {
    fixture = TestBed.createComponent(DashboardHeroComponent);
    comp    = fixture.componentInstance;
    heroEl  = fixture.debugElement.query(By.css('.hero')); // find hero element

    // pretend that it was wired to something that supplied a hero
    expectedHero = new Hero(42, 'Test Name');
    comp.hero = expectedHero;
    fixture.detectChanges(); // trigger initial data binding
});

Answer 3

product在测试中加载组件实例后,需要在组件实例上设置该值.

这里的示例是输入中的一个简单组件,您可以将其用作用例的基础:

@Component({
  selector: 'dropdown',
  directives: [NgClass],
  template: `
    <div [ngClass]="{open: open}">
    </div>
  `,
})
export class DropdownComponent {
  @Input('open') open: boolean = false;

  ngOnChanges() {
    console.log(this.open);
  }
}

并进行相应的测试:

it('should open', injectAsync([TestComponentBuilder], (tcb: TestComponentBuilder) => {
  return tcb.createAsync(DropdownComponent)
  .then(fixture => {
    let el = fixture.nativeElement;
    let comp: DropdownComponent = fixture.componentInstance;

    expect(el.className).toEqual('');

    // Update the input
    comp.open = true; // <-----------

    // Apply
    fixture.detectChanges(); // <-----------

    var div = fixture.nativeElement.querySelector('div');
    // Test elements that depend on the input
    expect(div.className).toEqual('open');
  });
}));

请参阅此plunkr作为示例:https://plnkr.co/edit/YAVD4s？p = preview .

Answer 4

我经常这样做:

describe('ProductThumbnail', ()=> {
  it('should work',
    injectAsync([ TestComponentBuilder ], (tcb: TestComponentBuilder) => {
      return tcb.createAsync(TestCmpWrapper).then(rootCmp => {
        let cmpInstance: ProductThumbnail =  
               <ProductThumbnail>rootCmp.debugElement.children[ 0 ].componentInstance;

        expect(cmpInstance.openProductPage()).toBe(/* whatever */)
      });
  }));
}

@Component({
 selector  : 'test-cmp',
 template  : '<product-thumbnail [product]="mockProduct"></product-thumbnail>',
 directives: [ ProductThumbnail ]
})
class TestCmpWrapper { 
    mockProduct = new Product(); //mock your input 
}

请注意,使用这种方法product,ProductThumbnail类中的任何其他字段都可以是私有的(这是我比Thierry的方法更喜欢它的主要原因,尽管事实上它更加冗长).