前端单元测试入门3-react测试

1.react测试体验

1.1安装

create-react-app react-test
cd react-test

1.2 创建sum.js

module.exports = function(a,b){
  return a+b;
}

1.3 创建sum.spec.js

let sum = require('./sum');
it('a+b',function(){
    expect(sum(1,2)).toBe(3);
});

1.4 运行测试

npm test

2.enzyme测试

• Shallow Rendering(浅渲染)指的是，将一个组件渲染成虚拟DOM对象，但是只渲染第一层，不渲染所有子组件，所以处理速度非常快。它不需要DOM环境，因为根本没有加载进DOM
• find()方法：只支持简单选择器 类选择器、id选择器、标签选择器、复合选择器

2.1 安装enzyme

npm i enzyme enzyme-adapter-react-16 -D

2.2 创建 TodoInput.js

import React, { Component } from 'react';
export default class TodoInput extends Component {
    handleKeyDown = (event) => {
        let code = event.keyCode;
        if (code == 13) {
            let text = event.target.value;
            this.props.addTodo(text);
            event.target.value = '';
        }
    }
    addTodo = () => {
        let text = this.todo.value;
        this.props.addTodo(text);
        this.todo.value = '';
    }
    render() {
        return (
            <div>
                <input ref={input => this.todo = input} onKeyDown={this.handleKeyDown} />
                <input id="addBtn" onClick={this.addTodo} defaultValue="增加" />
            </div>
        )
    }
}

2.3 创建 TodoInput.spec.js

import React from 'react';
import Enzyme,{shallow} from 'enzyme';
import TodoInput from './TodoInput';
import Adapter from 'enzyme-adapter-react-16'; 
Enzyme.configure({adapter:new Adapter()});
//http://airbnb.io/enzyme/docs/api/ShallowWrapper/find.html
//http://airbnb.io/enzyme/docs/api/selector.html
it('shoud render 请输入',function(){
    const wrapper  = shallow(<TodoInput/>);
    const h3 = wrapper.find('h3');
    const input = wrapper.find('input');
    expect(h3.text()).toBe('待办事项');
    expect(input.props().defaultValue).toBe('请输入');
});

2.3 创建 TodoList.js

import React, { Component } from 'react';
import TodoItem from './TodoItem';
export default class TodoList extends Component {
    render() {
        return (
            <ul>
                {
                    this.props.todos.map(todo => <TodoItem
                        key={todo.id}
                        todo={todo}
                        delTodo={this.props.delTodo}
                        toggleTodo={this.props.toggleTodo} />)
                }
            </ul>
        )
    }
}

2.4 点击事件

import React from 'react';
import Enzyme,{shallow} from 'enzyme';
import TodoInput from './TodoInput';
import Adapter from 'enzyme-adapter-react-16'; 
Enzyme.configure({adapter:new Adapter()});
//http://airbnb.io/enzyme/docs/api/ShallowWrapper/find.html
//http://airbnb.io/enzyme/docs/api/selector.html
describe('测试TodoInput',function(){
    let todos;
    beforeEach(()=>{
        todos =[{text:'1'},{text:'2'}];
    });
    it('shoud render 请输入',function(){
        let wrapper =  shallow(<TodoInput/>);
        const h3 = wrapper.find('h3');
        const input = wrapper.find('input');
        expect(h3.text()).toBe('待办事项');
        expect(input.props().defaultValue).toBe('请输入');
    });

    it('点击按钮的时候调用addTodo方法',function(){
        let addTodo = jest.fn();
        let wrapper = shallow(<TodoInput addTodo = {addTodo}/>);
        let button = wrapper.find('button');
        button.simulate('click');
        expect(addTodo).toBeCalled();
    });
});

2.5 TDD

• TDD是测试驱动开发（Test-Driven Development）是敏捷开发中的一项核心实践和技术，也是一种设计方法论
• TDD的原理是在开发功能代码之前，先编写单元测试用例代码，测试代码确定需要编写什么产品代码

创建reducer.js

const ADD_TODO = 'ADD_TODO';
const DEL_TODO = 'DEL_TODO';
let INIT_STATE = [{id:1,text:'1'},{id:2,text:'2'}];
function reducer(state=INIT_STATE,action={}){
  switch(action.type){
      case ADD_TODO:
          return [...state,action.todo];
      case DEL_TODO:
          return state.filter(item=>item.id != action.id);
      default:
          return state;    
  }
}
module.exports = reducer;

创建reducer.spec.js

let reducer = require('./reducer');
const ADD_TODO = 'ADD_TODO';
const DEL_TODO = 'DEL_TODO';
describe('reducer',()=>{
    let INIT_STATE = [{id:1,text:'1'},{id:2,text:'2'}];

    it('初始状态',()=>{
        expect(reducer(undefined,{})).toEqual(INIT_STATE);
    });

    it('增加todo',()=>{
        let todos = reducer(INIT_STATE,{type:ADD_TODO,todo:{id:3,text:'3'}});
        expect(todos).toEqual([...INIT_STATE,{id:3,text:'3'}]);
    });
    it('删除todo',()=>{
        let todos = reducer(INIT_STATE,{type:DEL_TODO,id:2});
        expect(todos).toEqual([{id:1,text:'1'}]);
    });
});

2.6 测试点击事件

import React from 'react';
import Enzyme,{shallow} from 'enzyme';
import TodoItem from './TodoItem';
import Adapter from 'enzyme-adapter-react-16'; 
import { wrap } from 'module';
Enzyme.configure({adapter:new Adapter()});
//http://airbnb.io/enzyme/docs/api/ShallowWrapper/find.html
//http://airbnb.io/enzyme/docs/api/selector.html
describe('TodoItem',function(){
    it('todo',()=>{
        const wrapper = shallow(<TodoItem todo={{id:1,text:'1'}}/>);
        expect(wrapper.text()).toMatch(/1/);
        expect(wrapper.hasClass('todo')).toBe(true);
        expect(wrapper.hasClass('todo-selected')).toBe(false);
    });
    it('todo-selected',()=>{
        const wrapper = shallow(<TodoItem todo={{id:1,text:'1'}}/>);
        expect(wrapper.text()).toMatch(/1/);
        wrapper.simulate('click');
        expect(wrapper.hasClass('todo')).toBe(false);
        expect(wrapper.hasClass('todo-selected')).toBe(true);
    });
});

2.7 mount

mount将React组件加载为真实的DOM

• .get(index)：返回指定位置的子组件的DOM节点
• .at(index)：返回指定位置的子组件
• .text()：返回当前组件的文本内容
• .html()：返回当前组件的HTML代码形式
• .props()：返回根组件的所有属性
• .prop(key)：返回根组件的指定属性
• .state([key])：返回根组件的状态

import React from 'react';
import Enzyme,{mount} from 'enzyme';
import TodoApp from './TodoApp';
import Adapter from 'enzyme-adapter-react-16'; 
Enzyme.configure({adapter:new Adapter()});
describe('TodoApp',function(){
   it('addTodo',()=>{
    let wrapper = mount(<TodoApp/>);
    let len = wrapper.find('li').length;
    wrapper.find('button').at(0).simulate('click');
    expect(wrapper.find('li').length).toBe(len + 1);
   });
   it('delTodo',()=>{
    let wrapper = mount(<TodoApp/>);
    let len = wrapper.find('li').length;
    wrapper.find('button').at(1).simulate('click');
    expect(wrapper.find('li').length).toBe(len - 1);
   });
});

3. 参考

• create-react-app
• jest
• expect
• jest中文网
• enzyme
• Jasmine
• istanbul
• prop-types