code: function configureSauceLabs (config) {
    var SAUCE = process.env.SAUCE === 'true';
    var username = process.env.SAUCE_USERNAME;
    var accessKey = process.env.SAUCE_ACCESS_KEY;
  
    if (!SAUCE || !username || !accessKey) {
      console.warn('SauceLabs is not enabled');
      return;
    }
  
    var project = require('./package.json');
    var testName = project.name + ' v' + project.version;
    var build = testName + ' Build #' + process.env.TRAVIS_JOB_NUMBER + ' @ ' + new Date();
  
    /* eslint camelcase:off */
    var sauceLaunchers = {
      SauceLabs_Chrome_Latest: {
        base: 'SauceLabs',
        platform: 'Windows 10',
        browserName: 'chrome'
      },
      SauceLabs_Firefox_Latest: {
        base: 'SauceLabs',
        platform: 'Windows 10',
        browserName: 'firefox'
      },
      SauceLabs_Safari_Latest: {
        base: 'SauceLabs',
        platform: 'macOS 10.12',
        browserName: 'safari'
      },
      SauceLabs_IE_9: {
        base: 'SauceLabs',
        platform: 'Windows 7',
        browserName: 'internet explorer',
        version: '9'
      },
      SauceLabs_IE_Edge: {
        base: 'SauceLabs',
        platform: 'Windows 10',
        browserName: 'microsoftedge'
      },
    };
  
    config.reporters.push('saucelabs');
    config.browsers = Object.keys(sauceLaunchers);
    config.customLaunchers = Object.assign(config.customLaunchers || {}, sauceLaunchers);
    config.sauceLabs = {
      build: build,
      testName: testName,
      tags: [project.name],
    };
  }
docs: Configures Sauce Labs emulated browsers/devices.
  https://github.com/karma-runner/karma-sauce-launcher