text: // karma.conf.js
  module.exports = function (config) {
    config.set({
      browsers: ['Firefox'],
      frameworks: ['mocha', 'detectBrowsers'],
      detectBrowsers: {
        enabled: true,
        usePhantomJS: false,
        postDetection(availableBrowser) {
          // modify to enable additional browsers if available
          const runBrowsers = ['Firefox', 'Chrome'];
          const browsers = [];
          for (let i = 0; i < runBrowsers.length; i += 1) {
            if (~availableBrowser.indexOf(runBrowsers[i])) {
              browsers.push(runBrowsers[i]);
            }
          }
          return browsers;
        },
      },
      singleRun: true,
      files: [
        '.build/tests.js',
      ],
      plugins: [
        'karma-mocha',
        'karma-chrome-launcher',
        'karma-firefox-launcher',
        'karma-detect-browsers',
      ],
    });
  };
  