# File lib/fog/aws/requests/iam/add_user_to_group.rb, line 32
        def add_user_to_group(group_name, user_name)
          unless data[:groups].key?(group_name)
            raise Fog::AWS::IAM::NotFound.new("The group with name #{group_name} cannot be found.")
          end

          unless data[:users].key?(user_name)
            raise Fog::AWS::IAM::NotFound.new("The user with name #{user_name} cannot be found.")
          end

          unless data[:groups][group_name][:members].include?(user_name)
            data[:groups][group_name][:members] << user_name
          end

          Excon::Response.new.tap do |response|
            response.status = 200
            response.body = { 'RequestId' => Fog::AWS::Mock.request_id }
          end
        end