给webpack增加单元测试功能

1、参考文章：https://juejin.im/post/5d2542606fb9a07ecb0bcfe7

2、修改依赖文件的版本号：

    "jsdom": "^13.0.0",
    "jsdom-global": "^3.0.2",

3、撰写webpack.test.js 文件：

const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const VueLoaderPlugin = require('vue-loader/lib/plugin');
const {CleanWebpackPlugin} = require('clean-webpack-plugin'); 


module.exports = {
    devtool: 'inline-cheap-module-source-map',
    entry:{
        index:path.resolve(__dirname,'../src/app.js')
    },
    output:{
        filename:'js/[name].[hash].js',
        path:path.resolve(__dirname,'../dist'),
    },
    resolve:{
        extensions:['.js','.vue','.json'],
        alias:{
            "@":path.resolve('src')
        }
    },
    stats: { 
        warningsFilter: (warning) => /Conflicting order between/gm.test(warning),
        children: false 
    },
    module:{
        rules:[
            {
                test:/\.vue$/,
                use:'vue-loader?cacheDirectory=true',
                include:path.resolve(__dirname,'../src'),
                exclude:/node_modules/
            },
            {
                test:/\.(png|gif|jpeg|jpg)$/,
                use:[
                    {
                        loader:'url-loader?cacheDirectory=true',
                        options:{
                            name:'img/[name].[ext]',
                            limit:1024
                        }
                    }
                ],
                include:path.resolve(__dirname,'../src'),
                exclude:/node_modules/
            },
            {
                test: /\.(js|ts)/,
                use: [
                    {
                        loader: 'istanbul-instrumenter-loader',
                        options: { esModules: true }
                    },
                    'babel-loader?cacheDirectory=true'
                ]
            },
        ]
    },
    plugins:[
        new CleanWebpackPlugin(),
        new VueLoaderPlugin(),
        new HtmlWebpackPlugin({
            template:path.resolve(__dirname,'../src/index.html')
        })
    ],
    externals: [require('webpack-node-externals')()]
}

注意，这里是没有将vue等基础库，打包成dll文件的。