# File lib/fog/aws/requests/iam/update_group.rb, line 37
        def update_group(group_name, options = {})
          raise Fog::AWS::IAM::NotFound.new(
            "The user with name #{group_name} cannot be found."
          ) unless self.data[:groups].key?(group_name)

          response = Excon::Response.new

          group = self.data[:groups][group_name]

          new_path       = options['NewPath']
          new_group_name = options['NewGroupName']

          if new_path
            unless new_path.match(/\A\/[a-zA-Z0-9]+\/\Z/)
              raise Fog::AWS::IAM::ValidationError,
                "The specified value for path is invalid. It must begin and end with / and contain only alphanumeric characters and/or / characters."
            end

            group[:path] = new_path
          end

          if new_group_name
            self.data[:groups].delete(group_name)
            self.data[:groups][new_group_name] = group
          end

          response.status = 200
          response.body = {
            'Group'     => {},
            'RequestId' => Fog::AWS::Mock.request_id
          }

          response
        end