用Jest测试Webpack构建的React组件 [英] Testing Webpack built React components with Jest

问题描述

我遇到了一个问题，我需要在Webpack正在构建的React应用程序上运行Jest测试.问题在于处理Webpack通常使用加载程序处理的CSS文件和图像等的require.我需要知道什么是正确测试组件的最佳方法.

React组件:

import React from 'react';
// The CSS file is the problem as I want to actually test what it
// returns after webpack has built it.
import style from './boilerplate.css';

var Boilerplate = React.createClass({
    render: function() {
        return (
            <div>
                <h1 className={style.title}>react-boilerplate</h1>
                <p className={style.description}>
                    A React and Webpack boilerplate.
                </p>
            </div>
        );
    }
});

export default Boilerplate;

开玩笑的测试:

jest.dontMock('./boilerplate.js');

var Boilerplate = require('./boilerplate.js');
var React = require('react/addons');
var TestUtils = React.addons.TestUtils;

describe('boilerplate', function() {

    var component;

    beforeEach(function() {
        component = TestUtils.renderIntoDocument(
            <Boilerplate />
        );
    });

    it('has a h1 title', function() {
        // I want to actually use 'findRenderedDOMComponentWithClass'
        // but cannot because I need to run the Webpack build to add a
        // CSS class to this element.
        var title = TestUtils.findRenderedDOMComponentWithTag(component, 'h1');
        expect(title.getDOMNode().textContent).toEqual('react-boilerplate');
    });

    it('has a paragraph with descriptive text', function() {
        var paragraph = TestUtils.findRenderedDOMComponentWithTag(component, 'p');
        expect(paragraph.getDOMNode().textContent).toEqual('A React and Webpack boilerplate.');
    });

});

我遇到了这个问题，这使我确信我在我自己尝试了所有这些方法的正确方法，但是遇到的所有解决方案都存在问题:

解决方案1: 使用一个scriptPreprocessor文件，该文件会除去需要Webpack构建的非Javascript文件的requires，例如需要.css，.less，.jpegs等.这样，我们可以测试React组件，而不能进行其他测试.

问题:我想测试Webpack构建所创建的一些功能.例如，我使用本地可互操作的CSS，并且我想测试从Webpack创建的require('whaterver.css')返回的CSS类的对象.我还想使用React/TestUtils中的findRenderedDOMComponentWithClass，这意味着我需要通过Webpack构建CSS.

解决方案2: 使用scriptPreprocessor脚本，该脚本通过Webpack运行组件并构建测试文件(例如 jest-webpack 确实)并在此输出上运行测试.

问题:我们不再像现在使用Webpacks __webpack_require__(1)那样使用Jest的自动模拟.每次运行测试文件时，构建速度都很慢.

解决方案3: 与解决方案2相似，但是在运行npm test来解决缓慢的构建时间之前，仅对所有测试文件运行一个构建.

问题:与解决方案2相同.没有自动嘲笑.

我是在错误的道路上吗，还是有人对此有任何答案?我想念明显的东西吗?

解决方案

我最近构建了 Jestpack 它将Jest与Webpack集成在一起，这意味着您可以使用Webpack的所有功能，包括CSS模块，文件加载，代码拆分，CommonJS/AMD/ES2015导入等，以及Jest的自动模拟.

I have come across a problem where I need to run Jest tests on a React application that is being built by Webpack. The problem is handling the require of CSS files and images etc that Webpack would usually process with a loader. I need to know about what is the best approach to test my components correctly.

The React component:

import React from 'react';
// The CSS file is the problem as I want to actually test what it
// returns after webpack has built it.
import style from './boilerplate.css';

var Boilerplate = React.createClass({
    render: function() {
        return (
            <div>
                <h1 className={style.title}>react-boilerplate</h1>
                <p className={style.description}>
                    A React and Webpack boilerplate.
                </p>
            </div>
        );
    }
});

export default Boilerplate;

The Jest test:

jest.dontMock('./boilerplate.js');

var Boilerplate = require('./boilerplate.js');
var React = require('react/addons');
var TestUtils = React.addons.TestUtils;

describe('boilerplate', function() {

    var component;

    beforeEach(function() {
        component = TestUtils.renderIntoDocument(
            <Boilerplate />
        );
    });

    it('has a h1 title', function() {
        // I want to actually use 'findRenderedDOMComponentWithClass'
        // but cannot because I need to run the Webpack build to add a
        // CSS class to this element.
        var title = TestUtils.findRenderedDOMComponentWithTag(component, 'h1');
        expect(title.getDOMNode().textContent).toEqual('react-boilerplate');
    });

    it('has a paragraph with descriptive text', function() {
        var paragraph = TestUtils.findRenderedDOMComponentWithTag(component, 'p');
        expect(paragraph.getDOMNode().textContent).toEqual('A React and Webpack boilerplate.');
    });

});

I have come across this question which reassured me I was on the right lines having tried all these approaches myself but I have issues with all of the solutions I have come across:

Solution 1: Use a scriptPreprocessor file which strips out requires of non Javascript files that require a Webpack build e.g requiring .css, .less, .jpegs etc. This way we can tests the React component but nothing else.

Problem: I want to test some of the functionality that the Webpack build creates. E.g I use local, interoperable CSS and I want to test the Object of CSS classes returned from a require('whaterver.css') which Webpack creates. I also want to use findRenderedDOMComponentWithClass from React/TestUtils which means I need to build the CSS through Webpack.

Solution 2: Use scriptPreprocessor script which runs the component through Webpack and builds a test file (like jest-webpack does) and run tests on this output.

Problem: We can no longer use Jest's auto mocking as we would now be using Webpacks __webpack_require__(1). This is also slow to build every time you run a test file.

Solution 3: Much like solution 2 but run only one build for all test files before running npm test to solve the slow build time.

Problem: Same as Solution 2. No auto mocking.

Am I on the wrong path here or does anyone have any answers for this? Am I missing the obvious?

解决方案

I recently built Jestpack which integrates Jest with Webpack meaning you can use all of Webpack's features including CSS modules, file loading, code splitting, CommonJS / AMD / ES2015 imports etc. along with Jest's auto mocking.

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