code: function NyanCat(baseReporterDecorator, formatError, config) {
    var self = this;
    var defaultOptions = function() {
      return {
        suppressErrorReport: false,
        suppressErrorHighlighting: false,
        numberOfRainbowLines: 4,
        renderOnRunCompleteOnly: false
      };
    };
  
    self.options = defaultOptions();
  
    if (config && config.nyanReporter) {
      // merge defaults
      Object.keys(self.options).forEach(function(optionName){
        if (config.nyanReporter.hasOwnProperty(optionName)) {
          self.options[optionName] = config.nyanReporter[optionName];
        }
      });
    }
  
    self.adapters = [fs.writeSync.bind(fs.writeSync, 1)];
    dataTypes.setErrorFormatterMethod(formatError);
  
    if (self.options.suppressErrorHighlighting) {
      dataTypes.suppressErrorHighlighting();
    }
  }
docs: NyanCat constructor