code: function errMessageFormat (showDiff, pos, title, msg, stack) {
    if (showDiff) {
      return format.red('  ' + pos + ') ' + title + ':\n' + msg) + format.gray('\n' + stack + '\n')
    }
    return format.red('  ' + pos + ') ' + title + ':\n') +
      format.white('     ' + msg) +
      format.white('\n' + stack + '\n')
  }
docs: Return formated error message
  @private
  @param{boolean} is diff message
  @param{number} index of message in Error queue
  @param{string} test suite title
  @param{string} error message
  @param{string} error stack