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，它由 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state 然后通过它映射并渲染一个 User 组件，其中包含数据数组的每个元素的 props。
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 的第 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 的第 23 行是复选框的三元表达式
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');
})
});
最佳答案
您需要针对三元表达式的两个条件(而不仅仅是一个)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注释:
对于 clickStarHandler 和 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，当 isFollowed/isStarred 匹配 active 和匹配 idle 时，您需要满足条件.相当简单的过程，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 }); .
用于测试应用:
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，只需操作用户属性；例如，更改 wrapper.setProps({ isStarred: "active"}) 或 wrapper.setProps({ isStarred: "idle"})，然后搜索 输入并根据其属性进行测试:
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
});
附带说明，您可以使用 object destructuring和 spread syntax大大简化您的 React 组件代码。
关于reactjs - 如何在 React 组件中对这些三元表达式实现 100% 的测试覆盖率，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/57656203/