custom-fe/test/unit/karma.conf.js

// This is a karma config file. For more details see
//   http://karma-runner.github.io/0.13/config/configuration-file.html
// we are also using it with karma-webpack
//   https://github.com/webpack/karma-webpack

var path = require('path')
var merge = require('webpack-merge')
var baseConfig = require('../../build/webpack.base.conf')
var utils = require('../../build/utils')
var webpack = require('webpack')
var projectRoot = path.resolve(__dirname, '../../')

var webpackConfig = merge(baseConfig, {
  // use inline sourcemap for karma-sourcemap-loader
  module: {
    rules: utils.styleLoaders()
  },
  devtool: '#inline-source-map',
  // vue: {
  //   loaders: {
  //     js: 'isparta'
  //   }
  // },
  plugins: [
    new webpack.DefinePlugin({
      'process.env': require('../../config/test.env')
    })
  ]
})

// no need for app entry during tests
delete webpackConfig.entry

// make sure isparta loader is applied before eslint
// webpackConfig.module.preLoaders = webpackConfig.module.preLoaders || []
// webpackConfig.module.preLoaders.unshift({
//   test: /\.js$/,
//   loader: 'isparta',
//   include: path.resolve(projectRoot, 'src')
// })

// // only apply babel for test files when using isparta
// webpackConfig.module.loaders.some(function (loader, i) {
//   if (loader.loader === 'babel') {
//     loader.include = path.resolve(projectRoot, 'test/unit')
//     return true
//   }
// })

module.exports = function (config) {
  config.set({
    // to run in additional browsers:
    // 1. install corresponding karma launcher
    //    http://karma-runner.github.io/0.13/config/browsers.html
    // 2. add it to the `browsers` array below.
    browsers: ['FirefoxHeadless'],
    frameworks: ['mocha', 'sinon-chai'],
    reporters: ['mocha'],
    customLaunchers: {
      'FirefoxHeadless': {
        base: 'Firefox',
        flags: [
          '-headless',
        ]
      }
    },
    files: [
      './index.js'
    ],
    preprocessors: {
      './index.js': ['webpack', 'sourcemap']
    },
    webpack: webpackConfig,
    webpackMiddleware: {
      noInfo: true
    },
    mochaReporter: {
      showDiff: true
    },
    coverageReporter: {
      dir: './coverage',
      reporters: [
        { type: 'lcov', subdir: '.' },
        { type: 'text-summary' }
      ]
    }
  })
}