Angular 2 单元测试数据从父组件传递到子组件
Posted
技术标签:
【中文标题】Angular 2 单元测试数据从父组件传递到子组件【英文标题】:Angular 2 unit testing data passed from parent component to child component 【发布时间】:2016-10-25 06:03:02 【问题描述】:我有一个关于我看到的(极少数)测试从父组件传递到子组件的数据示例的方式的问题。目前,在Angular2 docs 中,他们正在通过检查子组件的 dom 值来测试数据是否已从父组件传递到子组件。我对这种方法的问题是它强制父规范了解子组件的 html 结构。父组件的工作只是将数据传递给子组件。一个例子……
我有一个故事组件如下:
'use strict';
import Component, OnInit, Input from '@angular/core';
import StoryService from '../../services/story.service';
import StoryModel from '../../models/story-model';
import AlbumCover from './album-cover/album-cover';
import Author from "./author/author";
import StoryDuration from "./story-duration/story-duration";
@Component(
selector: 'story',
templateUrl: 'build/components/story/story.html',
providers: [StoryService],
directives: [AlbumCover, Author, StoryDuration]
)
export class Story implements OnInit
@Input('id') id:number;
public story:StoryModel;
constructor(private storyService:StoryService)
ngOnInit()
this.getStory();
private getStory()
this.storyService.getStory(this.id).subscribe(story => this.story = story);
注意它是如何在@Component
装饰器的directives
数组中具有AlbumCover
组件依赖关系的。
这是我的故事模板:
<div *ngIf="story">
<album-cover [image]="story.albumCover" [title]="story.title"></album-cover>
<div class="author-duration-container">
<author [avatar]="story.author.avatar" [name]="story.author.name"></author>
<story-duration [word-count]="story.wordCount"></story-duration>
</div>
</div>
请注意<album-cover [image]="story.albumCover" [title]="story.title"></album-cover>
行,我将story.albumCover
从Story
控制器绑定到AlbumCover
的image
属性。这一切都很完美。现在开始测试:
import provide from '@angular/core';
import beforeEach, beforeEachProviders, describe, expect, injectAsync, it, setBaseTestProviders, resetBaseTestProviders from '@angular/core/testing';
import HTTP_PROVIDERS from '@angular/http';
import BROWSER_APP_DYNAMIC_PROVIDERS from "@angular/platform-browser-dynamic";
import TEST_BROWSER_STATIC_PLATFORM_PROVIDERS, ADDITIONAL_TEST_BROWSER_PROVIDERS from '@angular/platform-browser/testing';
import ComponentFixture, TestComponentBuilder from '@angular/compiler/testing';
import Observable from 'rxjs/Observable';
// TODO: this pattern of importing 'of' can probably go away once rxjs is fixed
// https://github.com/ReactiveX/rxjs/issues/1713
import 'rxjs/add/observable/of';
resetBaseTestProviders();
setBaseTestProviders(
TEST_BROWSER_STATIC_PLATFORM_PROVIDERS,
[BROWSER_APP_DYNAMIC_PROVIDERS, ADDITIONAL_TEST_BROWSER_PROVIDERS]
);
import Story from './story';
import StoryModel from '../../models/story-model';
import StoryService from '../../services/story.service';
var mockStory =
id: 1,
title: 'Benefit',
albumCover: 'images/placeholders/story-4.jpg',
author:
id: 2,
name: 'Brett Beach',
avatar: 'images/placeholders/author-1.jpg'
,
wordCount: 4340,
content: '<p>This is going to be a great book! I <strong>swear!</strong></p>'
;
class MockStoryService
public getStory(id):Observable<StoryModel>
return Observable.of(mockStory);
describe('Story', () =>
var storyFixture,
story,
storyEl;
beforeEachProviders(() => [
HTTP_PROVIDERS
]);
beforeEach(injectAsync([TestComponentBuilder], (tcb:TestComponentBuilder) =>
return tcb
.overrideProviders(Story, [
provide(StoryService,
useClass: MockStoryService
)
])
.createAsync(Story)
.then((componentFixture:ComponentFixture<Story>) =>
storyFixture = componentFixture;
story = componentFixture.componentInstance;
storyEl = componentFixture.nativeElement;
componentFixture.detectChanges();
);
));
describe(`ngOnInit`, () =>
describe(`storyService.getStory`, () =>
it(`should be called, and on success, set this.story`, () =>
spyOn(story.storyService, 'getStory').and.callThrough();
story.ngOnInit();
expect(story.storyService.getStory).toHaveBeenCalled();
expect(story.story.title).toBe('Benefit');
);
);
);
it('should not show the story component if story does not exist', () =>
story.story = null;
storyFixture.detectChanges();
expect(storyEl.children.length).toBe(0);
);
it('should show the story component if story exists', () =>
story.story = mockStory;
storyFixture.detectChanges();
expect(storyEl.children.length).not.toBe(0);
);
describe('story components', () =>
beforeEach(() =>
story.story = mockStory;
storyFixture.detectChanges();
);
describe('album cover', () =>
var element,
img;
beforeEach(() =>
element = storyEl.querySelector('album-cover');
img = element.querySelector('img');
);
it(`should be passed the story albumCover and title to the album cover component`, () =>
expect(img.attributes.src.value).toBe(mockStory.albumCover);
expect(img.attributes.alt.value).toBe(mockStory.title);
);
);
describe('author', () =>
var element,
img,
nameEl;
beforeEach(() =>
element = storyEl.querySelector('author');
img = element.querySelector('img');
nameEl = element.querySelector('.name');
);
it(`should be passed the author name and avatar`, () =>
expect(img.attributes.src.value).toBe(story.story.author.avatar);
expect(img.attributes.alt.value).toBe(story.story.author.name);
expect(nameEl.innerText).toBe(story.story.author.name);
);
);
describe('story duration', () =>
var element;
beforeEach(() =>
element = storyEl.querySelector('.story-duration');
);
it(`should be passed the word count to generate the total read time`, () =>
story.story.wordCount = 234234;
storyFixture.detectChanges();
expect(element.innerText).toBe(`852 min read`);
);
);
);
);
看看我的describe('album cover'...
。我通过这种期望的方式是找到<album-cover>
元素,然后在其中找到<img>
标记,然后检查<img>
的DOM 属性。对我来说,这个期望应该在 album-cover.spec.ts
内部 - 而不是 story.spec.ts
。
我的问题是:有没有办法测试父组件是否在不依赖读取 dom 值的情况下将数据传递给子组件?
【问题讨论】:
【参考方案1】:您可以使用overrideTemplate
传递视图,仅用于测试。
return tcb
.overrideTemplate(AlbumCover, '<div>valueFromParent</div>')
.overrideProviders(Story, [
【讨论】:
Gunter,这正是我想要的。刚刚更新了我的测试,它运行良好。谢谢!!!!以上是关于Angular 2 单元测试数据从父组件传递到子组件的主要内容,如果未能解决你的问题,请参考以下文章