code: function(startOptions) {
      if (!this._isCoverageEnabled()) {
        return;
      }
      attachMiddleware.serverMiddleware(startOptions.app, {
        configPath: this.project.configPath(),
        root: this.project.root,
        fileLookup: fileLookup
      });
    }
docs: If coverage is enabled attach coverage middleware to the express server run by ember-cli
  @param {Object} startOptions - Express server start options