1、在build文件夹中创建testing.js文件

// 配置环境变量 type 为 testing
process.env.type = '"testing"'
// 引入build.js文件
require('./build')

2、修改config文件夹中的prod.env.js文件

module.exports = {
  NODE_ENV: '"production"',
  // 将上文设置的环境变量，赋值到 type 属性上
  type: process.env.type
}

3、在package.json文件中添加npm run testing命令

"testing": "node build/testing.js", // 添加testing命令
"build": "node build/build.js"

4、config ->index.js中把build这个命令复制一份改成testing(此步为了打包到不同文件夹)

build: {
    env: require('./prod.env'),
    // Template for index.html
    index: path.resolve(__dirname, '../dist/index.html'),

    // Paths
    assetsRoot: path.resolve(__dirname, '../dist'),
    assetsSubDirectory: 'static',
    assetsPublicPath: '/mshop/',

    /**
     * Source Maps
     */

    productionSourceMap: true,
    // https://webpack.js.org/configuration/devtool/#production
    devtool: '#source-map',

    // Gzip off by default as many popular static hosts such as
    // Surge or Netlify already gzip all static assets for you.
    // Before setting to `true`, make sure to:
    // npm install --save-dev compression-webpack-plugin
    productionGzip: false,
    productionGzipExtensions: ['js', 'css'],

    // Run the build command with an extra argument to
    // View the bundle analyzer report after build finishes:
    // `npm run build --report`
    // Set to `true` or `false` to always turn it on or off
    bundleAnalyzerReport: process.env.npm_config_report
  },
  testing: {
    env: require('./prod.env'),
    index: path.resolve(__dirname, '../testing/index.html'),
    assetsRoot: path.resolve(__dirname, '../testing'),
    assetsSubDirectory: 'static',
    assetsPublicPath: '/',
    productionSourceMap: true,
    // Gzip off by default as many popular static hosts such as
    // Surge or Netlify already gzip all static assets for you.
    // Before setting to `true`, make sure to:
    // npm install --save-dev compression-webpack-plugin
    productionGzip: false,
    productionGzipExtensions: ['js', 'css'],
    // Run the build command with an extra argument to
    // View the bundle analyzer report after build finishes:
    // `npm run build --report`
    // Set to `true` or `false` to always turn it on or off
    bundleAnalyzerReport: process.env.npm_config_report
  },

5、修改build->webpack.prod.conf文件

1. 修改filename

   new HtmlWebpackPlugin({

        filename: process.env.type == '"testing"' ? config.testing.index : config.build.index
      }),
   

2. 修改output

      output: {
      path: process.env.type == '"testing"' ? config.testing.assetsRoot : config.build.assetsRoot,
    },
   

6、修改build->build.js文件

路径都修改为根据正式、测试环境判断（不然执行npm run testing, npm run build命令时输出的文件有问题）

rm(path.join(process.env.type == '"testing"' ? config.testing.assetsRoot : config.build.assetsRoot, process.env.type == '"testing"' ? config.testing.assetsSubDirectory : config.build.assetsSubDirectory), err => {

7、根据不同环境配置不同域名地址

let baseUrl
if (process.env.NODE_ENV === 'production') {
  if (process.env.type === 'testing') { // 测试环境
    baseUrl = '测试环境地址'
  } else {                              // 正式环境
    baseUrl = '正式环境地址'
  }
} else {                               // 本地环境
  baseUrl = '本地环境地址'
}

最后执行:
    npm run testing 就会执行测试环境配置的地址，并生成testing文件夹
    npm run build就会执行正式环境配置的地址，并生成dist文件夹