TODO Do not expect require to be included before plugins
function requireUsed(files) {
  if (files) {
    var filePattern;

    for (var i = files.length; i > 0; i--) {
      filePattern = files[i] && files[i].pattern;

      if (typeof filePattern === 'string' && (filePattern.indexOf('\\karma-requirejs\\') !== -1 || filePattern.indexOf('/karma-requirejs/') !== -1)) {
        return true;
      }
      if (typeof filePattern === 'string' && (filePattern.indexOf('\\karma-cajon\\') !== -1 || filePattern.indexOf('/karma-cajon/') !== -1)) {
        return true;
      }
    }
  }

  return false;
}