使用 @Input() 进行 Angular2 单元测试

Question

我有一个在实例变量上使用 @Input() 注释的组件，我正在尝试为 openProductPage() 方法编写单元测试，但我有点迷茫关于我如何设置我的单元测试。我可以使该实例变量 public，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 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

在测试中加载组件实例后，您需要在组件实例上设置 product 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);
  }
}

以及相应的测试：

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');
  });
}));

将此 plunkr 视为示例：https://plnkr.co/edit/YAVD4s?p=preview。

Answer 2

我通常会这样做：

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 product 和 ProductThumbnail class 上的任何其他字段可以 使用这种方法是私有的（这是主要原因我更喜欢它而不是 Thierry 的方法，尽管它有点冗长）。

Answer 3

如果您使用 TestBed.configureTestingModule 来编译您的测试组件，这是另一种方法。它与公认的答案基本相同，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 4

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

还要确保最后调用fixture.detectChanges();，否则属性将不会绑定到组件。

工作示例

// 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
});

使用 @Input() 进行 Angular2 单元测试

Angular2 unit test with @Input()

unit-testing

jasmine

typescript

angular

angular-test