前端单元测试入门3react测试

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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

正文完
react.js 测试
发表至：无分类
2019-09-10
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