Jes*_*nan 8 javascript testing jsdom
摘要:
我试图测试一个侦听其中的本机DOM事件的React组件componentWillMount.
我发现jsdom(@8.4.0)在调度事件和添加事件监听器时没有按预期工作.
我可以提取的最简单的代码:
window.addEventListener('click', () => {
throw new Error("success")
})
const event = new Event('click')
document.dispatchEvent(event)
throw new Error('failure')
这引发了"失败".
语境:
这是我试图测试的组件的提取/简化版本.你可以在Webpackbin上看到它.
import React from 'react'
export default class Example extends React.Component {
constructor() {
super()
this._onDocumentClick = this._onDocumentClick.bind(this)
}
componentWillMount() {
this.setState({ clicked: false })
window.addEventListener('click', this._onDocumentClick)
}
_onDocumentClick() {
const clicked = this.state.clicked || false
this.setState({ clicked: !clicked })
}
render() {
return <p>{JSON.stringify(this.state.clicked)}</p>
}
}
这是我正在尝试编写的测试.
import React from 'react'
import ReactDOM from 'react-dom'
import { mount } from 'enzyme'
import Example from '../src/example'
describe('test', () => {
it('test', () => {
const wrapper = mount(<Example />)
const event = new Event('click')
document.dispatchEvent(event)
// at this point, I expect the component to re-render,
// with updated state.
expect(wrapper.text()).to.match(/true/)
})
})
只是为了完整性,这是我的test_helper.js初始化jsdom:
import { jsdom } from 'jsdom'
import chai from 'chai'
const doc = jsdom('<!doctype html><html><body></body></html>')
const win = doc.defaultView
global.document = doc
global.window = win
Object.keys(window).forEach((key) => {
if (!(key in global)) {
global[key] = window[key]
}
})
复制案例:
我在这里有一个repro案例:https://github.com/jbinto/repro-jsdom-events-not-firing
git clone https://github.com/jbinto/repro-jsdom-events-not-firing.git
cd repro-jsdom-events-not-firing
npm install
npm test
您正在调度该事件,document因此window不会看到它,因为默认情况下它不会冒泡.您需要创建bubbles设置为的事件true.例:
var jsdom = require("jsdom");
var document = jsdom.jsdom("");
var window = document.defaultView;
window.addEventListener('click', function (ev) {
console.log('window click', ev.target.constructor.name,
ev.currentTarget.constructor.name);
});
document.addEventListener('click', function (ev) {
console.log('document click', ev.target.constructor.name,
ev.currentTarget.constructor.name);
});
console.log("not bubbling");
var event = new window.Event("click");
document.dispatchEvent(event);
console.log("bubbling");
event = new window.Event("click", {bubbles: true});
document.dispatchEvent(event);
这里的问题是提供的jsdom document实际上并没有被酶测试使用.
酶利用renderIntoDocument从React.TestUtils.
{
renderIntoDocument: function(instance) {
var div = document.createElement('div');
// None of our tests actually require attaching the container to the
// DOM, and doing so creates a mess that we rely on test isolation to
// clean up, so we're going to stop honoring the name of this method
// (and probably rename it eventually) if no problems arise.
// document.documentElement.appendChild(div);
return ReactDOM.render(instance, div);
},
// ...
}
这意味着我们所有的酶测试都不会针对提供的jsdom执行document,而是执行与任何文档分离的div节点.
酶仅使用document为静态方法提供的jsdom ,例如getElementById等.它不用于存储/操作DOM元素.
为了进行这些类型的测试,我求助于实际调用ReactDOM.render,并使用DOM方法在输出上断言.
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