reactjs - 如何在反应组件中对这些三元表达式实现 100% 的测试覆盖率
问题描述
我正在尝试学习测试驱动开发,所以我创建了一个简单的培训应用程序,由 2 个简单的工作组件 App.js 组成,它将来自虚拟本地 JSON 文件的数据数组保存到 App.js 组件状态然后映射通过它并为数据数组的每个元素渲染一个带有道具的用户组件。所以我有 3 条未覆盖的行,它们都包含“if 语句”,我想对它们实现 100% 的测试覆盖率,所以请帮忙。以下是测试结果。
这些是 App.js 第 18 行和第 32 行中未覆盖的行是每个函数中的三元表达式
clickFollowHandler(id) {
this.setState(prevState => {
const updatedUsers = prevState.users.map(user => {
if (user.id === id) {
user.isFollowed === 'active' ? user.isFollowed = 'idle' : user.isFollowed = 'active'
}
return user
})
return {
users: updatedUsers
}
})
}
clickStarHandler(id) {
this.setState(prevState => {
const updatedUsers = prevState.users.map(user => {
if (user.id === id) {
user.isStared === 'active' ? user.isStared = 'idle' : user.isStared = 'active'
}
return user
})
return {
users: updatedUsers
}
})
}
这是 User.js 第 23 行是复选框三元表达式
return(
<div className={classes.container} key={id}>
<img className={classes.imageContainer} src={myImage} alt={name} />
<div className={classes.contentContainer}>
<div className={classes.contentContainerRow1}>
<div className={classes.name}>name: {name}</div>
<button onClick={() => handleFollowClick(id)}>
{isFollowed === 'active' ? 'Unfollow' : 'Follow'}
</button>
</div>
<div className={classes.contentContainerRow2}>
<div className={classes.date}>date: {date}</div>
<div className={classes.time}>reading time: {readingTime}</div>
<input
className={classes.hvrIconPop}
checked={isStared === 'active' ? true : false}
onChange={() => handleStarClick(id)}
type='checkbox'
/>
</div>
</div>
</div>
)
现在这是我的 App.test.js
import React from 'react';
import ReactDOM from 'react-dom';
import {shallow, mount} from './enzyme';
import App from './App';
jest.mock('./data/users-data.json')
let {user} = require('./data/users-data.json')
describe('App Component', () => {
it('calling the clickFollowHandler method from App Component has the expected effect on the state of the first user', () => {
const AppComponent = shallow(<App />)
const wrapper = AppComponent.instance()
wrapper.clickFollowHandler('5d552d0058f193f2795fc814')
expect(wrapper.state.users[0].isFollowed).toMatch('idle')
})
})
describe('App Component', () => {
it('calling the clickStarHandler method from App Component has the expected effect on the state of the second user', () => {
const AppComponent = shallow(<App />)
const wrapper = AppComponent.instance()
wrapper.clickStarHandler('5d552d00b20b141dff10d2a2')
expect(wrapper.state.users[1].isStared).toEqual('idle')
})
})
和我的 User.test.js
import React from 'react';
import renderer from 'react-test-renderer';
import {shallow, mount} from '../../enzyme';
import User from './User';
const users = {
"id": "5d552d0058f193f2795fc814",
"isFollowed": "active",
"isStared": "idle",
"image": "./assets/images/avata.png",
"readingTime": 20,
"name": "Walton Morton",
"date": "Aug 9"
};
it('renders correctly when there are no users', () => {
const tree = renderer.create(<User
key={''}
id={''}
name={''}
date={''}
readingTime={''}
isStared={''}
isFollowed={''}
image={''}
handleFollowClick={() => {}}
handleStarClick={() => {}}
/>).toJSON();
expect(tree).toMatchSnapshot();
});
it('renders correctly when there is one user', () => {
const tree = renderer.create(<User
key={users.id}
id={users.id}
name={users.name}
date={users.date}
readingTime={users.readingTime}
isStared={users.isStared}
isFollowed={users.isFollowed}
image={users.image}
handleFollowClick={() => 'test'}
handleStarClick={() => {}}
/>).toJSON();
expect(tree).toMatchSnapshot();
});
it('when the follow button is clicked a callback is executed', () => {
const mockFollowClick = jest.fn();
const mockStarClick = jest.fn();
const tree = renderer.create(<User
key={users.id}
id={users.id}
name={users.name}
date={users.date}
readingTime={users.readingTime}
isStared={users.isStared}
isFollowed={users.isFollowed}
image={users.image}
handleFollowClick={mockFollowClick}
handleStarClick={mockStarClick}
/>)
const button = tree.root.findByType('button');
const input = tree.root.findByType('input');
button.props.onClick();
expect(mockFollowClick).toHaveBeenCalled();
button.props.onClick();
expect(mockFollowClick).toHaveBeenCalledWith('5d552d0058f193f2795fc814');
input.props.onChange();
expect(mockStarClick).toHaveBeenCalled();
})
describe('User Component', () => {
it('clicking on the button will trigger the click handler', () => {
const mockFollowHandler = jest.fn();
const mockStarHandler = jest.fn();
const wrapper = mount(<User
key={users.id}
id={users.id}
name={users.name}
date={users.date}
readingTime={users.readingTime}
isStared={users.isStared}
isFollowed={users.isFollowed}
image={users.image}
handleFollowClick={mockFollowHandler}
handleStarClick={mockStarHandler}
/>)
wrapper.find('button').simulate('click');
expect(mockFollowHandler).toHaveBeenCalledWith('5d552d0058f193f2795fc814')
})
it('changing the star checkbox will trigger an onChange handler', () => {
const mockFollowHandler = jest.fn();
const mockStarHandler = jest.fn();
const wrapper = mount(<User
key={users.id}
id={users.id}
name={users.name}
date={users.date}
readingTime={users.readingTime}
isStared={users.isStared}
isFollowed={users.isFollowed}
image={users.image}
handleFollowClick={mockFollowHandler}
handleStarClick={mockStarHandler}
/>)
wrapper.find('input').simulate('change');
expect(mockStarHandler).toHaveBeenCalledWith('5d552d0058f193f2795fc814');
})
});
解决方案
您需要针对三元表达式的两个条件(不仅仅是一个)进行测试。由于我看不到完整的代码,我将尝试提供一些简短的说明:
对于clickStarHandler
and clickFollowHandler
,您需要针对users
状态进行测试并手动调用类字段(正如您所做的那样)。但是,您需要满足isFollowed
/isStarred
匹配active
时和匹配时的条件idle
。相当直接的过程,但是,如果您需要更新users
状态以包含一些数据,那么您可以简单地使用wrapper.setState({ users: userData });
.
用于测试App
:
import React from 'react";
import { mount } from "enzyme";
import App from "../App";
// for simplicity, I'd recommend only using one user
const usersData = [
{
id: "5d552d0058f193f2795fc814",
isFollowed: "active",
isStarred: "idle",
image: "./assets/images/avatar.png",
readingTime: 20,
name: "Walton Morton",
date: "Aug 9"
}
];
// *optional* include any props that are needed for the App
const initialProps = {};
describe("App Component", () => {
let wrapper;
beforeEach(() => (
wrapper = mount(<App { ...initialProps }/>);
wrapper.setState({ users: usersData }); // not needed if user data is already defined in state
)}
it("sets the 'user.isStarred' state to 'active' or 'idle'", () => (
const invokeStarHandler = () => {
wrapper.instance().clickStarHandler("5d552d0058f193f2795fc814");
wrapper.update();
};
invokeStarHandler();
expect(wrapper.state("users[0].isStarred").toEqual("active");
invokeStarHandler();
expect(wrapper.state("users[0].isStarred").toEqual("idle");
});
it("sets the 'user.isFollowed' state to 'active' or 'idle'", () => (
const invokeFollowHandler = () => {
wrapper.instance().clickFollowHandler("5d552d0058f193f2795fc814");
wrapper.update();
};
invokeFollowHandler();
expect(wrapper.state("users[0].isFollowed").toEqual("idle");
invokeFollowHandler();
expect(wrapper.state("users[0].isFollowed").toEqual("active");
});
...etc.
});
对于Users
测试,只需操作用户道具;例如,更改wrapper.setProps({ isStarred: "active" })
or wrapper.setProps({ isStarred: "idle" })
,然后搜索input
并针对其道具进行测试:
import React from 'react";
import { mount } from "enzyme";
import Users from "../Users";
// include any props that are needed for the Users component
const initialProps = {
id: "5d552d0058f193f2795fc814",
isFollowed: "active",
isStarred: "idle",
image: "./assets/images/avatar.png",
readingTime: 20,
name: "Walton Morton",
date: "Aug 9"
}
describe("Users Component", () => {
let wrapper;
beforeEach(() => (
wrapper = mount(<Users { ...initialProps }/>);
)}
it("updates the input's 'checked' property based upon a 'isStarred' prop", () => (
expect(wrapper.find("input").props().checked).toBeFalsy();
wrapper.setProps({ isStarred: "active" });
expect(wrapper.find("input").props().checked).toBeTruthy();
});
...etc
});
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