old_contents: module.exports = function(karma) {
    karma.configure({
      // base path, that will be used to resolve files and exclude
      basePath: '../../',
  
      // list of files / patterns to load in the browser
      files: [
        'polymer/tools/test/mocha-htmltest.js',
        'polymer/conf/mocha.conf.js',
        'polymer/node_modules/chai/chai.js',
        'polymer/polymer.js',
        'polymer/test/js/*.js',
        {pattern: 'platform/*.js', included: false},
        {pattern: 'polymer/tools/**/*.js', included: false},
        {pattern: 'polymer/src/*.js', included: false},
        {pattern: 'polymer/test/**/*.html', included: false},
        {pattern: 'polymer/test/**/*.css', included: false},
        {pattern: 'polymer/test/**/*.js', included: false}
      ],
  
      // list of files to exclude
      exclude: [],
  
      frameworks: ['mocha'],
  
      // use dots reporter, as travis terminal does not support escaping sequences
      // possible values: 'dots', 'progress', 'junit', 'teamcity'
      // CLI --reporters progress
      reporters: ['progress'],
  
      // web server port
      // CLI --port 9876
      port: 9876,
  
      // cli runner port
      // CLI --runner-port 9100
      runnerPort: 9100,
  
      // enable / disable colors in the output (reporters and logs)
      // CLI --colors --no-colors
      colors: true,
  
      // level of logging
      // possible values: LOG_DISABLE || LOG_ERROR || LOG_WARN || LOG_INFO || LOG_DEBUG
      // CLI --log-level debug
      logLevel: karma.LOG_INFO,
  
      // enable / disable watching file and executing tests whenever any file changes
      // CLI --auto-watch --no-auto-watch
      autoWatch: true,
  
      // Start these browsers, currently available:
      // - Chrome
      // - ChromeCanary
      // - Firefox
      // - Opera
      // - Safari (only Mac)
      // - PhantomJS
      // - IE (only Windows)
      // CLI --browsers Chrome,Firefox,Safari
      browsers: ['ChromeCanary'],
  
      // If browser does not capture in given timeout [ms], kill it
      // CLI --capture-timeout 5000
      captureTimeout: 50000,
  
      // Auto run tests on start (when browsers are captured) and exit
      // CLI --single-run --no-single-run
      singleRun: true,
  
      // report which specs are slower than 500ms
      // CLI --report-slower-than 500
      reportSlowerThan: 500,
  
      // compile coffee scripts
      preprocessors: {
      },
  
      plugins: [
        'karma-mocha',
        'karma-chrome-launcher',
        'karma-firefox-launcher',
        'karma-script-launcher',
        'karma-crbot-reporter'
      ]
    });
  };
  
new_contents: module.exports = function(karma) {
    karma.configure({
      // base path, that will be used to resolve files and exclude
      basePath: '../../',
  
      // list of files / patterns to load in the browser
      files: [
        'polymer/tools/test/mocha-htmltest.js',
        'polymer/conf/mocha.conf.js',
        'polymer/node_modules/chai/chai.js',
        'polymer/polymer.js',
        'polymer/test/js/*.js',
        {pattern: 'platform/*.js', included: false},
        {pattern: 'polymer/tools/**/*.js', included: false},
        {pattern: 'polymer/src/**/*.js', included: false},
        {pattern: 'polymer/test/**/*.html', included: false},
        {pattern: 'polymer/test/**/*.css', included: false},
        {pattern: 'polymer/test/**/*.js', included: false}
      ],
  
      // list of files to exclude
      exclude: [],
  
      frameworks: ['mocha'],
  
      // use dots reporter, as travis terminal does not support escaping sequences
      // possible values: 'dots', 'progress', 'junit', 'teamcity'
      // CLI --reporters progress
      reporters: ['progress'],
  
      // web server port
      // CLI --port 9876
      port: 9876,
  
      // cli runner port
      // CLI --runner-port 9100
      runnerPort: 9100,
  
      // enable / disable colors in the output (reporters and logs)
      // CLI --colors --no-colors
      colors: true,
  
      // level of logging
      // possible values: LOG_DISABLE || LOG_ERROR || LOG_WARN || LOG_INFO || LOG_DEBUG
      // CLI --log-level debug
      logLevel: karma.LOG_INFO,
  
      // enable / disable watching file and executing tests whenever any file changes
      // CLI --auto-watch --no-auto-watch
      autoWatch: true,
  
      // Start these browsers, currently available:
      // - Chrome
      // - ChromeCanary
      // - Firefox
      // - Opera
      // - Safari (only Mac)
      // - PhantomJS
      // - IE (only Windows)
      // CLI --browsers Chrome,Firefox,Safari
      browsers: ['ChromeCanary'],
  
      // If browser does not capture in given timeout [ms], kill it
      // CLI --capture-timeout 5000
      captureTimeout: 50000,
  
      // Auto run tests on start (when browsers are captured) and exit
      // CLI --single-run --no-single-run
      singleRun: true,
  
      // report which specs are slower than 500ms
      // CLI --report-slower-than 500
      reportSlowerThan: 500,
  
      // compile coffee scripts
      preprocessors: {
      },
  
      plugins: [
        'karma-mocha',
        'karma-chrome-launcher',
        'karma-firefox-launcher',
        'karma-script-launcher',
        'karma-crbot-reporter'
      ]
    });
  };
  
subject: add new src files to test config