React+Redux单元测试一小时入门

1、工具介绍

• karma：测试过程管理工具。能够监控文件变化自动执行单元测试，能够缓存测试结果，能够console.log显示测试过程当中的变量

• mocha：测试框架。提供describe，it，beforeEach等函数管理你的 testcase，后面示例中会看到

• chai：BDD（行为驱动开发）和TDD（测试驱动开发）双测试风格的断言库

• enzyme：React测试工具，能够相似 jquery 风格的 api 操做react 节点

• sinon: 提供 fake 数据， 替换函数调用等功能

2、环境准备

工具安装就是 npm install，这里就再也不详述，主要的配置项目在karma.conf.js中，能够参考这个模板项目 react-redux-starter-kit 。若是项目中用到全局变量，好比jquery, momentjs等，须要在测试环境中全局引入，不然报错，例如，在karma.conf中引入全局变量jQuery:

{
    files: [
    './node_modules/jquery/jquery.min.js',
    {
      pattern: `./tests/test-bundler.js`,
      watched: false,
      served: true,
      included: true
    }
  ]
}

在test-bundler.js中设置全局的变量，包括chai, sinon等：

/* tests/test-bundler.js */

import 'babel-polyfill'
import sinon from 'sinon'
import chai from 'chai'
import sinonChai from 'sinon-chai'
import chaiAsPromised from 'chai-as-promised'
import chaiEnzyme from 'chai-enzyme'

chai.use(sinonChai)
chai.use(chaiAsPromised)
chai.use(chaiEnzyme())

global.chai = chai
global.sinon = sinon
global.expect = chai.expect
global.should = chai.should()

...

3、简单的函数测试

先热身看看简单的函数如何单元测试：

/* helpers/validator.js */

export function checkUsername (name) {
  if (name.length === 0 || name.length > 15) {
    return '用户名必须为1-15个字'
  }
  return ''
}

/* tests/helpers/validator.spec.js */

import * as Validators from 'helpers/validator'

describe('helpers/validator', () => {
    describe('Function: checkUsername', () => {
        it('Should not return error while input foobar.', () => {
            expect(Validators.checkUsername('foobar')).to.be.empty
        })
        it('Should return error while empty.', () => {
            expect(Validators.checkUsername('')).to.equal('用户名必须为1-15个字')
        })
        it('Should return error while more then 15 words.', () => {
            expect(Validators.checkUsername('abcdefghijklmnop')).to.equal('用户名必须为1-15个字')
            expect(Validators.checkUsername('一二三四五六七八九十一二三四五六')).to.equal('用户名必须为1-15个字')
        })
    })
})

describe能够屡次嵌套使用，更清晰的描述测试功能的结构。执行单元测试:
babel-node ./node_modules/karma/bin/karma start build/karma.conf

3、component测试

在 redux 的理念中，react 组件应该分为视觉组件 component 和 高阶组件 container，UI与逻辑分离，更利于测试。redux 的 example 里，这两种组件通常都分开文件去存放。本人认为，若是视觉组件须要屡次复用，应该与container分开来写，但若是基本不复用，或者能够复用的组件已经专门组件化了(下面例子就是)，那就不必分开写，能够写在一个文件里更方便管理，而后经过 export 和 export default 分别输出

/* componets/Register.js  */

import React, { Component, PropTypes } from 'react'
import { connect } from 'react-redux'
import {
  FormGroup,
  FormControl,
  FormLabel,
  FormError,
  FormTip,
  Button,
  TextInput
} from 'componentPath/basic/form'

export class Register extends Component {
  render () {
    const { register, onChangeUsername, onSubmit } = this.props
    <div style={{padding: '50px 130px'}}>
      <FormGroup>
        <FormLabel>用户名</FormLabel>
        <FormControl>
          <TextInput width='370px' limit={15} value={register.username} onChange={onChangeUsername} />
          <FormTip>请输入用户名</FormTip>
          <FormError>{register.usernameError}</FormError>
        </FormControl>
      </FormGroup>
      <FormGroup>
        <Button type='primary' onClick={onSubmit}>提交</Button>
      </FormGroup>
    </div>
  }
}

Register.propTypes = {
  register: PropTypes.object.isRequired,
  onChangeUsername: PropTypes.func.isRequired,
  onSubmit: PropTypes.func.isRequired
}

const mapStateToProps = (state) => {
  return {
    register: state.register
  }
}

const mapDispatchToProps = (dispatch) => {
  return {
    onChangeUsername: name => {
      ...
    },
    onSubmit: () => {
      ...
    }
  }
}

export default connect(mapStateToProps, mapDispatchToProps)(Register)

测试 componet，这里用到 enzyme 和 sinon：

import React from 'react'
import { bindActionCreators } from 'redux'
import { Register } from 'components/Register'
import { shallow } from 'enzyme'
import {
  FormGroup,
  FormControl,
  FormLabel,
  FormError,
  FormTip,
  Dropdown,
  Button,
  TextInput
} from 'componentPath/basic/form'

describe('rdappmsg/trade_edit/componets/Plan', () => {
  let _props, _spies, _wrapper
  let register = {
    username: '',
    usernameError: ''
  }

  beforeEach(() => {
    _spies = {}
    _props = {
      register,
      ...bindActionCreators({
        onChangeUsername: (_spies.onChangeUsername = sinon.spy()),
        onSubmit: (_spies.onSubmit = sinon.spy())
      }, _spies.dispatch = sinon.spy())
    }
    _wrapper = shallow(<Register {..._props} />)
  })

  it('Should render as a <div>.', () => {
    expect(_wrapper.is('div')).to.equal(true)
  })

  it('Should has two children.', () => {
    expect(_wrapper.children()).to.have.length(2);
  })

  it('Each element of form should be <FormGroup>.', () => {
      _wrapper.children().forEach(function (node) {
        expect(node.is(FormGroup)).to.equal(true);
      })
  })

  it('Should render username properly.', () => {
    expect(_wrapper.find(TextInput).prop('value')).to.be.empty
    _wrapper.setProps({register: {...register, username: 'foobar' }})
    expect(_wrapper.find(TextInput).prop('value')).to.equal('foobar')
  })

  it('Should call onChangeUsername.', () => {
    _spies.onChangeUsername.should.have.not.been.called
    _wrapper.find(TextInput).prop('onChange')('hello')
    _spies.dispatch.should.have.been.called
    
  })
})

beforeEach函数在每一个测试用例启动前作一些初始化工做

enzyme shallow 的用法跟 jquery 的dom操做相似，能够经过选择器过滤出想要的节点，能够接受 css 选择器或者react class，如：find('.someClass')， find(TextInput)

这里用到了 sinon 的spies, 能够观察到函数的调用状况。他还提供stub, mock功能，了解更多请 google

4、action 的测试

先来看一个普通的 action：

/* actions/register.js */

import * as Validator from 'helpers/validator'

export const CHANGE_USERNAME_ERROR = 'CHANGE_USERNAME_ERROR'

export function checkUsername (name) {
  return {
    type: CHANGE_USERNAME_ERROR,
    error: Validator.checkUsername(name)
  }
}

普通的 action 就是一个简单的函数，返回一个 object，测试起来跟前面的简单函数例子同样:

/* tests/actions/register.js */

import * as Actions from 'actions/register'

describe('actions/register', () => {
  describe('Action: checkUsername', () => {
    it('Should export a constant CHANGE_USERNAME_ERROR.', () => {
      expect(Actions.CHANGE_USERNAME_ERROR).to.equal('CHANGE_USERNAME_ERROR')
    })

    it('Should be exported as a function.', () => {
      expect(Actions.checkUsername).to.be.a('function')
    })
    
    it('Should be return an action.', () => {
      const action = Actions.checkUsername('foobar')
      expect(action).to.have.property('type', Actions.CHANGE_USERNAME_ERROR)
    })
    
    it('Should be return an action with error while input empty name.', () => {
      const action = Actions.checkUsername('')
      expect(action).to.have.property('error').to.not.be.empty
    })   
  })
   
})

再来看一下异步 action, 这里功能是改变 username 的同时发起检查:

export const CHANGE_USERNAME = 'CHANGE_USERNAME'

export function changeUsername (name) {
  return (dispatch) => {
    dispatch({
      type: CHANGE_USERNAME,
      name
    })
    dispatch(checkUsername(name))
  }
}

测试代码：

/* tests/actions/register.js */

import * as Actions from 'actions/register'

describe('actions/register', () => {
  let actions
  let dispatchSpy
  let getStateSpy

  beforeEach(function() {
    actions = []
    dispatchSpy = sinon.spy(action => {
      actions.push(action)
    })
  })

  describe('Action: changeUsername', () => {
    it('Should export a constant CHANGE_USERNAME.', () => {
      expect(Actions.CHANGE_USERNAME).to.equal('CHANGE_USERNAME')
    })

    it('Should be exported as a function.', () => {
      expect(Actions.changeUsername).to.be.a('function')
    })
    
    it('Should return a function (is a thunk).', () => {
      expect(Actions.changeUsername()).to.be.a('function')
    })
    
    it('Should be return an action.', () => {
      const action = Actions.checkUsername('foobar')
      expect(action).to.have.property('type', Actions.CHANGE_USERNAME_ERROR)
    })
    
    it('Should call dispatch CHANGE_USERNAME and CHANGE_USERNAME_ERROR.', () => {
      Actions.changeUsername('hello')(dispatchSpy)
      dispatchSpy.should.have.been.calledTwice

      expect(actions[0]).to.have.property('type', Actions.CHANGE_USERNAME)
      expect(actions[0]).to.have.property('name', 'hello')
      expect(actions[1]).to.have.property('type', Actions.CHANGE_USERNAME_ERROR)
      expect(actions[1]).to.have.property('error', '')
    }) 
  })
})

假如如今产品需求变动，要求实时在后台检查 username 的合法性, 就须要用到 ajax 了, 这里假设使用 Jquery 来实现 ajax 请求:

/* actions/register.js */

export const CHANGE_USERNAME_ERROR = 'CHANGE_USERNAME_ERROR'

export function checkUsername (name) {
  return (dispatch) => {
    $.get('/check', {username: name}, (msg) => {
      dispatch({
        type: CHANGE_USERNAME_ERROR,
        error: msg
      })
    })
  }
}

要测试 ajax 请求，能够用 sinon 的 fake XMLHttpRequest, 不用为了测试改动 action 任何代码:

/* tests/actions/register.js */

import * as Actions from 'actions/register'

describe('actions/register', () => {
  let actions
  let dispatchSpy
  let getStateSpy
  let xhr
  let requests

  beforeEach(function() {
    actions = []
    dispatchSpy = sinon.spy(action => {
      actions.push(action)
    })
    
    xhr = sinon.useFakeXMLHttpRequest()
    requests = []
    xhr.onCreate = function(xhr) {
      requests.push(xhr);
    };
  })

  afterEach(function() {
    xhr.restore();
  });

  describe('Action: checkUsername', () => {   
    it('Should call dispatch CHANGE_USERNAME_ERROR.', () => {
      Actions.checkUsername('foo@bar')(dispatchSpy)      
      const body = '不能含有特殊字符'
      
      // 手动设置 ajax response      
      requests[0].respond(200, {'Content-Type': 'text/plain'}, body)  
          
      expect(actions[0]).to.have.property('type', Actions. CHANGE_USERNAME_ERROR)
      expect(actions[0]).to.have.property('error', '不能含有特殊字符')
    }) 
  })
})

5、 reducer 的测试

reducer 就是一个普通函数 (state, action) => newState, 测试方法参考第三部分