You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: ipset_internal_test.go
    path of file: ./repos/AdGuardHome/internal/dnsforward
    
    the code of the file until where you have to start completion: package dnsforward

import (
	"net"
	"testing"

	"github.com/AdguardTeam/dnsproxy/proxy"
	"github.com/miekg/dns"
	"github.com/stretchr/testify/assert"
)

// fakeIpsetMgr is a fake aghnet.IpsetManager for tests.
type fakeIpsetMgr struct {
	ip4s []net.IP
	ip6s []net.IP
}

// Add implements the aghnet.IpsetManager interface for *fakeIpsetMgr.
func (m *fakeIpsetMgr) Add(host string, i
    
func TestIpsetCtx_process(t *testing.T) {
	ip4 := net.IP{1, 2, 3, 4}
	ip6 := net.IP{
		0x12, 0x34, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x56, 0x78,
	}

	req4 := createTestMessageWithType("example.com", dns.TypeA)
	req6 := createTestMessageWithType("example.com", dns.TypeAAAA)

	resp4 := &dns.Msg{
		Answer: []dns.RR{&dns.A{
			A: ip4,
		}},
	}
	resp6 := &dns.Msg{
		Answer: []dns.RR{&dns.AAAA{
			AAAA: ip6,
		}},
	}

	t.Run("nil", func(t *testing.T) {
		dctx := &dnsContext{
			proxyCtx: &proxy.DNSContext{},

			responseFromUpstream: true,
		}

		ictx := &ipsetCtx{}
		rc := ictx.process(dctx)
		assert.Equal(t, resultCodeSuccess, rc)

		err := ictx.close()
		assert.NoError(t, err)
	})

	t.Run("ipv4", func(t *testing.T) {
		dctx := &dnsContext{
			proxyCtx: &proxy.DNSContext{
				Req: req4,
				Res: resp4,
			},

			responseFromUpstream: true,
		}

		m := &fakeIpsetMgr{}
		ictx := &ipsetCtx{
			ipsetMgr: m,
		}

		rc := ictx.process(dctx)
		assert.Equal(t, resultCodeSuccess, rc)
		assert.Equal(t, []net.IP{ip4}, m.ip4s)
		assert.Empty(t, m.ip6s)

		err := ictx.close()
		assert.NoError(t, err)
	})

	t.Run("ipv6", func(t *testing.T) {
		dctx := &dnsContext{
			proxyCtx: &proxy.DNSContext{
				Req: req6,
				Res: resp6,
			},

			responseFromUpstream: true,
		}

		m := &fakeIpsetMgr{}
		ictx := &ipsetCtx{
			ipsetMgr: m,
		}

		rc := ictx.process(dctx)
		assert.Equal(t, resultCodeSuccess, rc)
		assert.Empty(t, m.ip4s)
		assert.Equal(t, []net.IP{ip6}, m.ip6s)

		err := ictx.close()
		assert.NoError(t, err)
	})
}