diff --git a/internal/aghnet/net_test.go b/internal/aghnet/net_test.go
index 730f1b4e..f4275c6c 100644
--- a/internal/aghnet/net_test.go
+++ b/internal/aghnet/net_test.go
@@ -11,7 +11,6 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/AdguardTeam/AdGuardHome/internal/aghtest"
 	"github.com/AdguardTeam/golibs/errors"
 	"github.com/AdguardTeam/golibs/netutil"
 	"github.com/AdguardTeam/golibs/testutil"
@@ -20,7 +19,7 @@ import (
 )
 
 func TestMain(m *testing.M) {
-	aghtest.DiscardLogOutput(m)
+	testutil.DiscardLogOutput(m)
 }
 
 // testdata is the filesystem containing data for testing the package.
@@ -196,10 +195,7 @@ func TestCheckPort(t *testing.T) {
 		require.NoError(t, err)
 		testutil.CleanupAndRequireSuccess(t, l.Close)
 
-		addr := l.Addr()
-		require.IsType(t, new(net.TCPAddr), addr)
-
-		ipp := addr.(*net.TCPAddr).AddrPort()
+		ipp := testutil.RequireTypeAssert[*net.TCPAddr](t, l.Addr()).AddrPort()
 		require.Equal(t, laddr.Addr(), ipp.Addr())
 		require.NotZero(t, ipp.Port())
 
@@ -215,10 +211,7 @@ func TestCheckPort(t *testing.T) {
 		require.NoError(t, err)
 		testutil.CleanupAndRequireSuccess(t, conn.Close)
 
-		addr := conn.LocalAddr()
-		require.IsType(t, new(net.UDPAddr), addr)
-
-		ipp := addr.(*net.UDPAddr).AddrPort()
+		ipp := testutil.RequireTypeAssert[*net.UDPAddr](t, conn.LocalAddr()).AddrPort()
 		require.Equal(t, laddr.Addr(), ipp.Addr())
 		require.NotZero(t, ipp.Port())
 
diff --git a/internal/aghnet/systemresolvers_others_test.go b/internal/aghnet/systemresolvers_others_test.go
index a9974e0a..8bc506a8 100644
--- a/internal/aghnet/systemresolvers_others_test.go
+++ b/internal/aghnet/systemresolvers_others_test.go
@@ -6,6 +6,7 @@ import (
 	"context"
 	"testing"
 
+	"github.com/AdguardTeam/golibs/testutil"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -17,9 +18,8 @@ func createTestSystemResolversImpl(
 	t.Helper()
 
 	sr := createTestSystemResolvers(t, hostGenFunc)
-	require.IsType(t, (*systemResolvers)(nil), sr)
 
-	return sr.(*systemResolvers)
+	return testutil.RequireTypeAssert[*systemResolvers](t, sr)
 }
 
 func TestSystemResolvers_Refresh(t *testing.T) {
diff --git a/internal/aghos/aghos_test.go b/internal/aghos/aghos_test.go
index 684f646e..3916d98e 100644
--- a/internal/aghos/aghos_test.go
+++ b/internal/aghos/aghos_test.go
@@ -3,9 +3,9 @@ package aghos_test
 import (
 	"testing"
 
-	"github.com/AdguardTeam/AdGuardHome/internal/aghtest"
+	"github.com/AdguardTeam/golibs/testutil"
 )
 
 func TestMain(m *testing.M) {
-	aghtest.DiscardLogOutput(m)
+	testutil.DiscardLogOutput(m)
 }
diff --git a/internal/aghtest/aghtest.go b/internal/aghtest/aghtest.go
index 31274718..850446e0 100644
--- a/internal/aghtest/aghtest.go
+++ b/internal/aghtest/aghtest.go
@@ -3,23 +3,11 @@ package aghtest
 
 import (
 	"io"
-	"os"
 	"testing"
 
 	"github.com/AdguardTeam/golibs/log"
 )
 
-// DiscardLogOutput runs tests with discarded logger output.
-//
-// TODO(a.garipov): Replace with testutil.
-func DiscardLogOutput(m *testing.M) {
-	// TODO(e.burkov): Refactor code and tests to not use the global mutable
-	// logger.
-	log.SetOutput(io.Discard)
-
-	os.Exit(m.Run())
-}
-
 // ReplaceLogWriter moves logger output to w and uses Cleanup method of t to
 // revert changes.
 func ReplaceLogWriter(t testing.TB, w io.Writer) {
diff --git a/internal/aghtls/aghtls_test.go b/internal/aghtls/aghtls_test.go
index 923ff063..7e5b99f9 100644
--- a/internal/aghtls/aghtls_test.go
+++ b/internal/aghtls/aghtls_test.go
@@ -4,14 +4,13 @@ import (
 	"crypto/tls"
 	"testing"
 
-	"github.com/AdguardTeam/AdGuardHome/internal/aghtest"
 	"github.com/AdguardTeam/AdGuardHome/internal/aghtls"
 	"github.com/AdguardTeam/golibs/testutil"
 	"github.com/stretchr/testify/assert"
 )
 
 func TestMain(m *testing.M) {
-	aghtest.DiscardLogOutput(m)
+	testutil.DiscardLogOutput(m)
 }
 
 func TestParseCiphers(t *testing.T) {
diff --git a/internal/dhcpd/dhcpd_unix_test.go b/internal/dhcpd/dhcpd_unix_test.go
index 38305076..0bf516cb 100644
--- a/internal/dhcpd/dhcpd_unix_test.go
+++ b/internal/dhcpd/dhcpd_unix_test.go
@@ -9,7 +9,6 @@ import (
 	"testing"
 	"time"
 
-	"github.com/AdguardTeam/AdGuardHome/internal/aghtest"
 	"github.com/AdguardTeam/golibs/testutil"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -17,7 +16,7 @@ import (
 )
 
 func TestMain(m *testing.M) {
-	aghtest.DiscardLogOutput(m)
+	testutil.DiscardLogOutput(m)
 }
 
 func testNotify(flags uint32) {
diff --git a/internal/dhcpd/v4_unix_test.go b/internal/dhcpd/v4_unix_test.go
index c8e4dd1f..411e36d9 100644
--- a/internal/dhcpd/v4_unix_test.go
+++ b/internal/dhcpd/v4_unix_test.go
@@ -482,7 +482,6 @@ func TestV4Server_updateOptions(t *testing.T) {
 
 		s, err := v4Create(conf)
 		require.NoError(t, err)
-
 		require.IsType(t, (*v4Server)(nil), s)
 
 		t.Run(tc.name, func(t *testing.T) {
diff --git a/internal/dnsforward/dns_test.go b/internal/dnsforward/dns_test.go
index 915455d2..acaf5f55 100644
--- a/internal/dnsforward/dns_test.go
+++ b/internal/dnsforward/dns_test.go
@@ -5,6 +5,7 @@ import (
 	"net/netip"
 	"testing"
 
+	"github.com/AdguardTeam/AdGuardHome/internal/aghalg"
 	"github.com/AdguardTeam/AdGuardHome/internal/aghtest"
 	"github.com/AdguardTeam/AdGuardHome/internal/filtering"
 	"github.com/AdguardTeam/dnsproxy/proxy"
@@ -449,12 +450,27 @@ func TestServer_ProcessDHCPHosts(t *testing.T) {
 }
 
 func TestServer_ProcessRestrictLocal(t *testing.T) {
-	ups := &aghtest.Upstream{
-		Reverse: map[string][]string{
-			"251.252.253.254.in-addr.arpa.": {"host1.example.net."},
-			"1.1.168.192.in-addr.arpa.":     {"some.local-client."},
+	const (
+		extPTRQuestion = "251.252.253.254.in-addr.arpa."
+		extPTRAnswer   = "host1.example.net."
+		intPTRQuestion = "1.1.168.192.in-addr.arpa."
+		intPTRAnswer   = "some.local-client."
+	)
+
+	ups := &aghtest.UpstreamMock{
+		OnAddress: func() (addr string) { return "upstream.example" },
+		OnExchange: func(req *dns.Msg) (resp *dns.Msg, err error) {
+			resp = aghalg.Coalesce(
+				aghtest.RespondTo(t, req, dns.ClassINET, dns.TypePTR, extPTRQuestion, extPTRAnswer),
+				aghtest.RespondTo(t, req, dns.ClassINET, dns.TypePTR, intPTRQuestion, intPTRAnswer),
+				new(dns.Msg).SetRcode(req, dns.RcodeNameError),
+			)
+
+			return resp, nil
 		},
+		OnClose: func() (err error) { return nil },
 	}
+
 	s := createTestServer(t, &filtering.Config{}, ServerConfig{
 		UDPListenAddrs: []*net.UDPAddr{{}},
 		TCPListenAddrs: []*net.TCPAddr{{}},
@@ -524,14 +540,26 @@ func TestServer_ProcessLocalPTR_usingResolvers(t *testing.T) {
 	const locDomain = "some.local."
 	const reqAddr = "1.1.168.192.in-addr.arpa."
 
-	s := createTestServer(t, &filtering.Config{}, ServerConfig{
-		UDPListenAddrs: []*net.UDPAddr{{}},
-		TCPListenAddrs: []*net.TCPAddr{{}},
-	}, &aghtest.Upstream{
-		Reverse: map[string][]string{
-			reqAddr: {locDomain},
+	s := createTestServer(
+		t,
+		&filtering.Config{},
+		ServerConfig{
+			UDPListenAddrs: []*net.UDPAddr{{}},
+			TCPListenAddrs: []*net.TCPAddr{{}},
 		},
-	})
+		&aghtest.UpstreamMock{
+			OnAddress: func() (addr string) { return "upstream.example" },
+			OnExchange: func(req *dns.Msg) (resp *dns.Msg, err error) {
+				resp = aghalg.Coalesce(
+					aghtest.RespondTo(t, req, dns.ClassINET, dns.TypePTR, reqAddr, locDomain),
+					new(dns.Msg).SetRcode(req, dns.RcodeNameError),
+				)
+
+				return resp, nil
+			},
+			OnClose: func() (err error) { return nil },
+		},
+	)
 
 	var proxyCtx *proxy.DNSContext
 	var dnsCtx *dnsContext
diff --git a/internal/filtering/filtering_test.go b/internal/filtering/filtering_test.go
index 4fc9182d..05869765 100644
--- a/internal/filtering/filtering_test.go
+++ b/internal/filtering/filtering_test.go
@@ -11,6 +11,7 @@ import (
 	"github.com/AdguardTeam/AdGuardHome/internal/aghtest"
 	"github.com/AdguardTeam/golibs/cache"
 	"github.com/AdguardTeam/golibs/log"
+	"github.com/AdguardTeam/golibs/testutil"
 	"github.com/AdguardTeam/urlfilter/rules"
 	"github.com/miekg/dns"
 	"github.com/stretchr/testify/assert"
@@ -18,7 +19,7 @@ import (
 )
 
 func TestMain(m *testing.M) {
-	aghtest.DiscardLogOutput(m)
+	testutil.DiscardLogOutput(m)
 }
 
 const (
diff --git a/internal/home/home_test.go b/internal/home/home_test.go
index 1a611588..2ce1d76d 100644
--- a/internal/home/home_test.go
+++ b/internal/home/home_test.go
@@ -3,10 +3,10 @@ package home
 import (
 	"testing"
 
-	"github.com/AdguardTeam/AdGuardHome/internal/aghtest"
+	"github.com/AdguardTeam/golibs/testutil"
 )
 
 func TestMain(m *testing.M) {
-	aghtest.DiscardLogOutput(m)
+	testutil.DiscardLogOutput(m)
 	initCmdLineOpts()
 }
diff --git a/internal/next/dnssvc/dnssvc_test.go b/internal/next/dnssvc/dnssvc_test.go
index 814e3bad..5e53ba49 100644
--- a/internal/next/dnssvc/dnssvc_test.go
+++ b/internal/next/dnssvc/dnssvc_test.go
@@ -10,13 +10,14 @@ import (
 	"github.com/AdguardTeam/AdGuardHome/internal/next/dnssvc"
 	"github.com/AdguardTeam/dnsproxy/upstream"
 	"github.com/AdguardTeam/golibs/errors"
+	"github.com/AdguardTeam/golibs/testutil"
 	"github.com/miekg/dns"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
 func TestMain(m *testing.M) {
-	aghtest.DiscardLogOutput(m)
+	testutil.DiscardLogOutput(m)
 }
 
 // testTimeout is the common timeout for tests.
diff --git a/internal/next/websvc/websvc_test.go b/internal/next/websvc/websvc_test.go
index 39ab3038..56acb862 100644
--- a/internal/next/websvc/websvc_test.go
+++ b/internal/next/websvc/websvc_test.go
@@ -11,7 +11,6 @@ import (
 	"testing"
 	"time"
 
-	"github.com/AdguardTeam/AdGuardHome/internal/aghtest"
 	"github.com/AdguardTeam/AdGuardHome/internal/next/agh"
 	"github.com/AdguardTeam/AdGuardHome/internal/next/dnssvc"
 	"github.com/AdguardTeam/AdGuardHome/internal/next/websvc"
@@ -21,7 +20,7 @@ import (
 )
 
 func TestMain(m *testing.M) {
-	aghtest.DiscardLogOutput(m)
+	testutil.DiscardLogOutput(m)
 }
 
 // testTimeout is the common timeout for tests.
diff --git a/internal/querylog/qlog_test.go b/internal/querylog/qlog_test.go
index f33401cc..cc470438 100644
--- a/internal/querylog/qlog_test.go
+++ b/internal/querylog/qlog_test.go
@@ -8,9 +8,9 @@ import (
 	"testing"
 	"time"
 
-	"github.com/AdguardTeam/AdGuardHome/internal/aghtest"
 	"github.com/AdguardTeam/AdGuardHome/internal/filtering"
 	"github.com/AdguardTeam/dnsproxy/proxyutil"
+	"github.com/AdguardTeam/golibs/testutil"
 	"github.com/AdguardTeam/golibs/timeutil"
 	"github.com/miekg/dns"
 	"github.com/stretchr/testify/assert"
@@ -18,7 +18,7 @@ import (
 )
 
 func TestMain(m *testing.M) {
-	aghtest.DiscardLogOutput(m)
+	testutil.DiscardLogOutput(m)
 }
 
 // TestQueryLog tests adding and loading (with filtering) entries from disk and
diff --git a/internal/stats/stats_test.go b/internal/stats/stats_test.go
index 5d86024b..bb2cc0d8 100644
--- a/internal/stats/stats_test.go
+++ b/internal/stats/stats_test.go
@@ -10,7 +10,6 @@ import (
 	"sync/atomic"
 	"testing"
 
-	"github.com/AdguardTeam/AdGuardHome/internal/aghtest"
 	"github.com/AdguardTeam/AdGuardHome/internal/stats"
 	"github.com/AdguardTeam/golibs/testutil"
 	"github.com/stretchr/testify/assert"
@@ -18,7 +17,7 @@ import (
 )
 
 func TestMain(m *testing.M) {
-	aghtest.DiscardLogOutput(m)
+	testutil.DiscardLogOutput(m)
 }
 
 // constUnitID is the UnitIDGenFunc which always return 0.
diff --git a/internal/updater/updater_test.go b/internal/updater/updater_test.go
index 6eed74fd..dbf0e069 100644
--- a/internal/updater/updater_test.go
+++ b/internal/updater/updater_test.go
@@ -11,7 +11,6 @@ import (
 	"testing"
 
 	"github.com/AdguardTeam/AdGuardHome/internal/aghalg"
-	"github.com/AdguardTeam/AdGuardHome/internal/aghtest"
 	"github.com/AdguardTeam/AdGuardHome/internal/version"
 	"github.com/AdguardTeam/golibs/testutil"
 	"github.com/stretchr/testify/assert"
@@ -21,7 +20,7 @@ import (
 // TODO(a.garipov): Rewrite these tests.
 
 func TestMain(m *testing.M) {
-	aghtest.DiscardLogOutput(m)
+	testutil.DiscardLogOutput(m)
 }
 
 func startHTTPServer(data string) (l net.Listener, portStr string) {