测试React:目标容器不是DOM元素 [英] Testing React: Target Container is not a DOM element
问题描述
我正在尝试在使用Webpack时使用Jest/Enzyme测试React组件.
I'm attempting to test a React component with Jest/Enzyme while using Webpack.
我有一个非常简单的测试@
I have a very simple test @
import React from 'react';
import { shallow } from 'enzyme';
import App from './App';
it('App', () => {
const app = shallow(<App />);
expect(1).toEqual(1);
});
它要拾取的相对成分是:
The relative component it's picking up is :
import React, { Component } from 'react';
import { render } from 'react-dom';
// import './styles/normalize.css';
class App extends Component {
render() {
return (
<div>app</div>
);
}
}
render(<App />, document.getElementById('app'));
但是，运行jest会导致失败:
However, running jest causes a failure:
Invariant Violation: _registerComponent(...): Target container is not a DOM element.
有错误@
at Object.<anonymous> (src/App.js:14:48)
at Object.<anonymous> (src/App.test.js:4:38)
at Object.<anonymous> (src/App.js:14:48)
at Object.<anonymous> (src/App.test.js:4:38)
测试文件引用第4行，这是<App />的导入，导致失败.堆栈跟踪显示App.js的第14行是失败的原因-仅仅是来自react-dom的render调用，这是我从未遇到过的挑战(该应用程序可从我的Webpack设置正确渲染)
The test files references line 4, which is the import of <App />, that causes a fail. The stack trace says line 14 of App.js is the reason for the failure -- which is nothing more than the render call from react-dom, something I've never had a challenge with (the app renders properly from my Webpack setup).
对于那些感兴趣的人(Webpack代码):
For those interested (Webpack code):
module.exports = {
entry: './src/App',
output: {
filename: 'bundle.js',
path: './dist'
},
module: {
loaders: [
{
test: /\.js?$/,
exclude: /node_modules/,
loader: 'babel',
query: {
presets: ['react', 'es2015']
}
},
{
test: /\.css$/,
loader: 'style!css-loader?modules&importLoaders=1&localIdentName=[name]__[local]___[hash:base64:5]'
},
{
test: /\.scss$/,
loader: 'style!css-loader?modules&importLoaders=1&localIdentName=[name]__[local]___[hash:base64:5]!sass'
}
]
}
}
还有我的package.json:
{
"name": "tic-tac-dux",
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
"dev": "webpack-dev-server --devtool eval --progress --colors --inline --hot --content-base dist/",
"test": "jest"
},
"jest": {
"moduleNameMapper": {
"^.+\\.(jpg|jpeg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm|wav|mp3|m4a|aac|oga)$": "<rootDir>/__mocks__/fileMock.js",
"^.+\\.(css|sass)$": "<rootDir>/__mocks__/styleMock.js"
}
},
"keywords": [],
"author": "",
"license": "ISC",
"devDependencies": {
"babel-core": "^6.17.0",
"babel-jest": "^16.0.0",
"babel-loader": "^6.2.5",
"babel-polyfill": "^6.16.0",
"babel-preset-es2015": "^6.16.0",
"babel-preset-react": "^6.16.0",
"css-loader": "^0.25.0",
"enzyme": "^2.4.1",
"jest": "^16.0.1",
"jest-cli": "^16.0.1",
"node-sass": "^3.10.1",
"react-addons-test-utils": "^15.3.2",
"react-dom": "^15.3.2",
"sass-loader": "^4.0.2",
"style-loader": "^0.13.1",
"webpack": "^1.13.2",
"webpack-dev-server": "^1.16.2"
},
"dependencies": {
"react": "^15.3.2",
"react-dom": "^15.3.2"
}
}
哦，如果有人要说在脚本之前没有加载div元素，这就是我的index.html:
Oh, and if anyone is going to say that the div element isn't being loaded before the script, here's my index.html:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>App</title>
</head>
<body>
<div id="app"></div>
<script src="/bundle.js"></script>
</body>
</html>
这个特殊的渲染问题可能是什么原因?与新的Jest更新到15.0有关吗?
What could be the reason for this peculiar rendering problem? Something to do with a new Jest update to 15.0?
推荐答案
App.jsx应该导出App类并且不执行其他操作，render应该在其他位置调用.
App.jsx is supposed to export the App class and do nothing more, render should be called elsewhere.
如果从App.jsx中删除render调用，该错误应该消失，则会弹出该错误，因为测试环境没有为DOM提供app id.
If you remove the render call from the App.jsx error should disappear, it pops up because the test environment doesn't supply the DOM with an app id.
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