reactjs – 如何使用React-Redux中的Mocha,Chai和Enzyme测试方法和回调

我必须为PlayerList容器和Player组件编写单元测试用例.为分支和道具编写测试用例是可以的,但是如何测试组件的方法及其中的逻辑.我的代码覆盖率不完整,因为没有测试方法.

场景：

父组件将对其方法onSelect的引用作为对子组件的回调传递.该方法在PlayerList组件中定义,但Player正在生成调用它的onClick事件.

父组件/容器：

import React, { Component } from 'react';
import {connect} from 'react-redux';
import {bindActionCreators} from 'redux';
import {selectTab} from '../actions/index';
import Player from './Player';

class PlayerList extends Component {    
    constructor(props){
        super(props);
    }

    onSelect(i) {
        if (!i) {
            this.props.selectPlayer(1);
        }
        else {
            this.props.selectPlayer(i);
        }
    }

    createListItems(){      
        return this.props.playerList.map((item, i)=>{
            return (                
                    <Player key={i} tab={item} onSelect={() => this.onSelect(item.id)} />
                )
        });
    }

    render() {
        return(
            <div className="col-md-12">
                <ul className="nav nav-tabs">                   
                    {this.createListItems()}
                </ul>   
            </div>
        )   
    }   
}

function mapStateToProps(state){
  return {
    playerList: state.playerList 
  }
}
function matchDispatchToProps(dispatch){
  return bindActionCreators({selectPlayer: selectPlayer}, dispatch);
}
export default connect(mapStateToProps, matchDispatchToProps)(PlayerList);

子组件：

import React, { Component } from 'react';
    class Player extends Component {    
        constructor(props){
            super(props);
        }

        render() {
            return(
                <li className={this.props.player.selected?'active':''}>
                    <a href="#"  onClick={() => this.props.onSelect(this.props.player.id)}>
                       <img src={this.props.player.imgUrl}     className="thumbnail"/>
                        {this.props.player.name}
                    </a>
                </li>
            )   
        }   
    }
    export default Player;

使用酶的.instance()方法访问组件方法

当然有几个先决条件.

>您必须首先使用酶的shallow或mount函数渲染组件,具体取决于您是否需要[和/或您希望如何]嵌套子项上的simulate事件.这也为您提供了一个酶包装器,您可以从中访问组件实例及其方法.
>您需要围绕这些实例方法包装sinon test spies并使用.update重新渲染以获取可以断言的spies包装器的版本.

例：

// Import requisite modules
import React from 'react';
import sinon from 'sinon';
import { mount } from 'enzyme';
import { expect } from 'chai';
import PlayerList from './PlayerList';

// Describe what you'll be testing
describe('PlayerList component', () => {
  // Mock player list
  const playerList = [
    {
      id    : 1,
      imgUrl: 'http://placehold.it/100?text=P1',
      name  : 'Player One'
    }
  ];

  // Nested describe just for our instance methods
  describe('Instance methods', () => {
    // Stub the selectPlayer method.
    const selectPlayer = sinon.stub();
    // Full DOM render including nested Player component
    const wrapper = mount(
      <PlayerList playerList={ playerList } selectPlayer={ selectPlayer } />
    );
    // Get the component instance
    const instance = wrapper.instance();

    // Wrap the instance methods with spies
    instance.createListItems = sinon.spy(instance.createListItems);
    instance.onSelect        = sinon.spy(instance.onSelect);

    // Re-render component. Now with spies!
    wrapper.update();

    it('should call createListItems on render', () => {
      expect(instance.createListItems).to.have.been.calledOnce;
    });

    it('should call onSelect on child link click', () => {
      expect(instance.onSelect).to.not.have.been.called;
      wrapper.find('li > a').at(0).simulate('click');
      expect(instance.onSelect).to.have.been.calledOnce;
      expect(instance.onSelect).to.have.been.calledWith(playerList[0].id);
    });
  });
});

笔记：

>当使用上面的代码为PlayerList和Player时,我发现你没有将一个名为player的道具分配给Player;相反,你正在分配item = {item}.为了让它在本地运行,我将其更改为< Player player = {item} ... />.
>在onSelect中,您正在检查收到的i参数是否为false,然后调用selectPlayer(1).我在上面的例子中没有包含测试用例,因为逻辑关注我的原因有两个：

>我想知道我是不是0？如果是这样,它将始终评估为falsey并传递到该块.
>因为Player调用onSelect(this.props.player.id),我想知道this.props.player.id是否会被定义？如果是这样,我想知道你为什么在props.playerList中有一个没有id属性的项目.

但是如果你想像现在一样测试那个逻辑,它看起来就像这样……

onSelect中的测试逻辑示例：

describe('PlayerList component', () => {
  …
  // Mock player list should contain an item with `id: 0`
  // …and another item with no `id` property.
  const playerList = [
    …, // index 0 (Player 1)
    {  // index 1
      id    : 0,
      imgUrl: 'http://placehold.it/100?text=P0',
      name  : 'Player Zero'
    },
    {  // index 2
      imgUrl: 'http://placehold.it/100?text=P',
      name  : 'Player ?'
    }
  ];
  describe('Instance methods', { … });
  describe('selectPlayer', () => {
    const selectPlayer = sinon.stub();
    const wrapper = mount(
      <PlayerList playerList={ playerList } selectPlayer={ selectPlayer } />
    );
    const instance = wrapper.instance();

    // There is no need to simulate clicks or wrap spies on instance methods
    // …to test the call to selectPlayer. Just call the method directly.
    it('should call props.selectPlayer with `id` if `id` is truthy', () => {
      instance.onSelect(playerList[0].id); // id: 1
      expect(selectPlayer).to.have.been.calledOnce;
      expect(selectPlayer).to.have.been.calledWith(playerList[0].id);
    });

    it('should call props.selectPlayer(1) if `id` is 0', () => {
      instance.onSelect(playerList[1].id); // id: 0
      expect(selectPlayer).to.have.been.calledTwice;
      expect(selectPlayer).to.have.been.calledWith(1);
    });

    it('should call props.selectPlayer(1) if `id` is undefined', () => {
      instance.onSelect(playerList[2].id); // undefined
      expect(selectPlayer).to.have.been.calledThrice;
      expect(selectPlayer).to.have.been.calledWith(1);
    });
  });
});