# File lib/fog/aws/requests/elb/set_load_balancer_policies_for_backend_server.rb, line 35
        def set_load_balancer_policies_for_backend_server(lb_name, instance_port, policy_names)
          if load_balancer = self.data[:load_balancers][lb_name]
            # Ensure policies exist
            policy_names.each do |policy_name|
              unless load_balancer['Policies']['Proper'].find { |p| p['PolicyName'] == policy_name }
                raise Fog::AWS::ELB::PolicyNotFound, "There is no policy with name #{policy_name} for load balancer #{lb_name}"
              end
            end

            # Update backend policies:
            description = load_balancer['BackendServerDescriptionsRemote'].find{|d| d["InstancePort"] == instance_port } || {}
            description["InstancePort"] = instance_port
            description["PolicyNames"] = policy_names
            load_balancer['BackendServerDescriptionsRemote'].delete_if{|d| d["InstancePort"] == instance_port }
            load_balancer['BackendServerDescriptionsRemote'] << description

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