# File lib/fog/aws/requests/elasticache/create_cache_subnet_group.rb, line 30
        def create_cache_subnet_group(name, subnet_ids, description = name)
          response = Excon::Response.new
          if self.data[:subnet_groups] && self.data[:subnet_groups][name]
            raise Fog::AWS::Elasticache::IdentifierTaken.new("CacheSubnetGroupAlreadyExists => The subnet group '#{name}' already exists")
          end

          collection = Fog::Compute[:aws]
          collection.region = @region
          subnets = collection.subnets

          subnets = subnet_ids.map { |snid| subnets.get(snid) }
          vpc_id = subnets.first.vpc_id

          data = {
            'CacheSubnetGroupName' => name,
            'CacheSubnetGroupDescription' => description,
            'SubnetGroupStatus' => 'Complete',
            'Subnets' => subnet_ids,
            'VpcId' => vpc_id
          }
          self.data[:subnet_groups][name] = data
          response.body = {
            "ResponseMetadata"=>{ "RequestId"=> Fog::AWS::Mock.request_id },
            'CreateCacheSubnetGroupResult' => { 'CacheSubnetGroup' => data }
          }
          response
        end