如何模拟Reaction测试中的状态和数据的值 [英] How can mock the value of a state and data in my react test
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问题描述
我正在为我的Reaction页面编写测试，但我的页面在其状态下使用isLoding，当加载页面时呈现"正在加载"，当加载但没有数据(来自FETCH请求)时呈现"找不到数据"，而当加载数据(来自FETCH请求)时加载欢迎页面。
我想编写一个测试，用于检查在下列情况下是否显示预期文本：
- 页面已加载，但未找到数据
- 页面已加载并包含数据
TypeError: Cannot read property 'map' of undefined
但我不确定为什么我的模拟数据是Data：Orders>；，其中包含数据，因此不应该是未定义的。
有人能告诉我如何改正测试吗？
WelcomePage.js
import React from "react";
import { Link } from "react-router-dom";
class WelcomePage extends React.Component {
constructor(props) {
super(props);
this.state = {
data: [],
isLoading: false,
};
}
componentDidMount() {
this.setState({ isLoading: true });
const proxyurl = "https://cors-anywhere.herokuapp.com/";
const url =
"mu url"
fetch(proxyurl + url)
.then((res) => res.json())
.then((data) => this.setState({ data: data, isLoading: false }));
}
render() {
const { data, isLoading } = this.state;
if (isLoading) {
return (
<div className="pageLoading">
<p>Loading...</p>
</div>
);
}
if (data.length === 0) {
return <p> no data found</p>;
}
return (
<div className="Welcome">
<div className="Details">
<p className="userID">
<strong>
Welcome {data.userForename} {data.userSurname}
</strong>
</p>
<button className="SignOut">
<Link to={{ pathname: "/LogIn" }}>Sign Out</Link>
</button>
</div>
<div className="InfoBox">
<p>
<strong>Orders</strong>{" "}
</p>
</div>
<div className="orderss">
{data.orders.map((order, index) => (
<ul className="orderBox" key={order.toString()+index}>
<li className="orderLink">
<Link
to={{
pathname: "/OrderDetails",
state: {
orderNumber: order.rollNumber,
userID: this.state.userID,
},
}}
>
Order number: {order.rollNumber}
</Link>
</li>
<li> Customer name: {order.customerFullName}</li>
</ul>
))}
</div>
</div>
);
}
}
export default WelcomePage;
欢迎.页面.测试.js
import React, { useState } from 'react';
import renderer from 'react-test-renderer';
import {render, unmountComponentAtNode } from 'react-dom';
import WelcomePage from './WelcomePage';
let container = null;
beforeEach(() => {
container = document.createElement('div');
document.body.appendChild(container);
})
afterEach(() => {
unmountComponentAtNode(container);
container.remove();
container = null;
})
test("test page renders as epxected when loading", () => {
const userId= "123456";
render(<WelcomePage location={userId}></UserWelcome>, container);
expect(container.innerHTML).toContain("Loading...");
});
test("mock fetch call, empty responce from db should return no data",
async () => {
const fakeResponse = [];
const userId = "1234567";
jest.spyOn(window, "fetch").mockImplementation(() => {
const fetchResponse = {
json: () => Promise.resolve(fakeResponse),
};
return Promise.resolve(fetchResponse);
});
await act(async () => {
render(<WelcomePage location={userId} />, container);
});
expect(container.innerHTML).toContain("no data");
window.fetch.mockRestore();
}
);
test("mock fetch call, valid responce from db should return applications", async () => {
//{ rates: { CAD: 1.42 } }
const fakeResponse = [
{
data: {
userId: 1234567,
userForename: "Joe",
userSurname: "Bloggs",
orders: [
{
orderNumber: 10000000001,
customerFullName: "Mrs Joes Bloggs",
userId: 1234567
},
]
}
}
];
const userId = "1234567";
jest.spyOn(window, "fetch").mockImplementation(() => {
const fetchResponse = {
json: () => Promise.resolve(fakeResponse)
};
return Promise.resolve(fetchResponse);
});
await act(async () => {
render(<WelcomePage location={userId} />, container);
});
expect(container.textContent).toContain("Order number: 10000000001");
window.fetch.mockRestore();
});
编辑-添加Package.json
{
"name": "sm-app",
"version": "0.1.0",
"private": false,
"dependencies": {
"@testing-library/jest-dom": "^4.2.4",
"@testing-library/react": "^9.5.0",
"@testing-library/user-event": "^7.2.1",
"bootstrap": "^4.5.3",
"moment": "^2.29.1",
"prop-types": "^15.7.2",
"react": "^17.0.1",
"react-app-polyfill": "^2.0.0",
"react-bootstrap": "^1.4.0",
"react-dom": "^17.0.1",
"react-router-dom": "^5.2.0",
"react-scripts": "3.4.4",
"react-spinners": "^0.9.0",
"reactstrap": "^8.6.0"
},
"scripts": {
"start": "react-scripts start",
"build": "react-scripts build",
"test": "react-scripts test",
"eject": "react-scripts eject"
},
"eslintConfig": {
"extends": "react-app"
},
"browserslist": {
"production": [
">0.2%",
"not dead",
"not op_mini all",
"ie >= 9"
],
"development": [
"last 1 chrome version",
"last 1 firefox version",
"last 1 safari version",
"ie 11"
]
},
"devDependencies": {
"prettier": "2.1.2",
"react-test-renderer": "^17.0.1"
}
}
推荐答案
测试用例
如您所见，您传递了不包含订单的空数组
test("mock fetch call, empty responce from db should return no data",
async () => {
const fakeResponse = []; <-- empty array which does not contain orders
const userId = "1234567";
jest.spyOn(window, "fetch").mockImplementation(() => {
const fetchResponse = {
json: () => Promise.resolve(fakeResponse),
};
return Promise.resolve(fetchResponse);
});
await act(async () => {
render(<WelcomePage location={userId} />, container);
});
expect(container.innerHTML).toContain("no data");
window.fetch.mockRestore();
}
);
因为它试图访问undefined和undefined没有map功能的订单时数据为空
{data.orders.map((order, index) => ( <-- problems here
<ul className="orderBox" key={order.toString()+index}>
<li className="orderLink">
<Link
to={{
pathname: "/OrderDetails",
state: {
orderNumber: order.rollNumber,
userID: this.state.userID,
},
}}
>
Order number: {order.rollNumber}
</Link>
</li>
<li> Customer name: {order.customerFullName}</li>
</ul>
))}
您可以这样更改它：
{data && data.orders && data.orders.map((order, index) => ( <-- changes
<ul className="orderBox" key={order.toString()+index}>
<li className="orderLink">
<Link
to={{
pathname: "/OrderDetails",
state: {
orderNumber: order.rollNumber,
userID: this.state.userID,
},
}}
>
Order number: {order.rollNumber}
</Link>
</li>
<li> Customer name: {order.customerFullName}</li>
</ul>
))}
注意：
- 将
fakeResponse作为数组传递时，需要将WelcomePage.js中的FETCH内setState更新为
if (data && data[0] && data[0]['data']) {
this.setState({
data: data[0]['data'], <-- changes
isLoading: false,
});
}
- 或将
fakeResponse更改为：
const fakeResponse = {
data: {
userId: 1234567,
userForename: "Joe",
userSurname: "Bloggs",
orders: [
{
orderNumber: 10000000001,
customerFullName: "Mrs Joes Bloggs",
userId: 1234567
},
]
}
};
将状态设置为：
if (data && data['data']) {
this.setState({
data: data['data'], <-- changes
isLoading: false,
});
}
检查数据是否为空的AND条件：
if (Object.keys(data).length === 0) {
return <p> no data found</p>;
}
这篇关于如何模拟Reaction测试中的状态和数据的值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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