    # File lib/fog/aws/requests/compute/attach_volume.rb, line 41
            def attach_volume(instance_id, volume_id, device)
              response = Excon::Response.new
              if instance_id && volume_id && device
                response.status = 200
                instance = self.data[:instances][instance_id]
                volume = self.data[:volumes][volume_id]
                if instance && volume
                  unless volume['status'] == 'available'
                    raise Fog::Compute::AWS::Error.new("Client.VolumeInUse => Volume #{volume_id} is unavailable")
                  end

                  data = {
                    'attachTime'  => Time.now,
                    'device'      => device,
                    'instanceId'  => instance_id,
                    'status'      => 'attaching',
                    'volumeId'    => volume_id
                  }
                  volume['attachmentSet'] = [data]
                  volume['status'] = 'attaching'
                  response.status = 200
                  response.body = {
                    'requestId' => Fog::AWS::Mock.request_id
                  }.merge!(data)
                  response
                elsif !instance
                  raise Fog::Compute::AWS::NotFound.new("The instance ID '#{instance_id}' does not exist.")
                elsif !volume
                  raise Fog::Compute::AWS::NotFound.new("The volume '#{volume_id}' does not exist.")
                end
              else
                message = 'MissingParameter => '
                if !instance_id
                  message << 'The request must contain the parameter instance_id'
                elsif !volume_id
                  message << 'The request must contain the parameter volume_id'
                else
                  message << 'The request must contain the parameter device'
                end
                raise Fog::Compute::AWS::Error.new(message)
              end
            end