Writing tests using Jasmine with Browserify, Babel and generating coverage with Istanbul

karma-conf.js

const istanbul = require( 'browserify-istanbul' )

module.exports = function(config) {
  config.set({
    basePath: '',
    frameworks: ['browserify', 'jasmine'],
    files: [
      // 'js/**/*.js',
      'js/utils/**/*.js',
      'test/spec/*.js'
    ],
    exclude: [
      'js/app.js', 'js/utils/*.js'
    ],
    preprocessors: {
      'test/spec/*.js': [ 'browserify' ],
      'js/**/*.js': ['browserify', 'coverage']
    },
    reporters: ['dots', 'coverage'],
    coverageReporter: {
      dir: './test/coverage',
      reporters: [
        { type: 'html', subdir: '.' },
        { type: 'text', subdir: '.', file: 'text.txt' },
      ]
    },
    browserify: {
        debug: true,
        bundleDelay: 1000,
        extensions: [ '.js' ],
        transform: [
          'babelify',
          istanbul( {
              // ignore: [ '**/spec/**', '**/fixture/**' ]
          } )
       ]
    },
    // port: 9876,
    colors: true,
    logLevel: config.LOG_INFO,
    autoWatch: false,
    browsers: ['Chrome'],
    singleRun: true
  });
};