diff --git a/internal/aghio/limitedreader.go b/internal/aghio/limitedreader.go
index 0f185da0..5b6c57d9 100644
--- a/internal/aghio/limitedreader.go
+++ b/internal/aghio/limitedreader.go
@@ -11,7 +11,7 @@ type LimitReachedError struct {
 	Limit int64
 }
 
-// Error implements error interface for LimitReachedError.
+// Error implements the error interface for LimitReachedError.
 //
 // TODO(a.garipov): Think about error string format.
 func (lre *LimitReachedError) Error() string {
diff --git a/internal/aghio/limitedreader_test.go b/internal/aghio/limitedreader_test.go
index b9514819..15c5fc81 100644
--- a/internal/aghio/limitedreader_test.go
+++ b/internal/aghio/limitedreader_test.go
@@ -1,38 +1,38 @@
 package aghio
 
 import (
-	"fmt"
 	"io"
 	"strings"
 	"testing"
 
+	"github.com/AdguardTeam/golibs/testutil"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
 func TestLimitReader(t *testing.T) {
 	testCases := []struct {
-		want error
-		name string
-		n    int64
+		wantErrMsg string
+		name       string
+		n          int64
 	}{{
-		want: nil,
-		name: "positive",
-		n:    1,
+		wantErrMsg: "",
+		name:       "positive",
+		n:          1,
 	}, {
-		want: nil,
-		name: "zero",
-		n:    0,
+		wantErrMsg: "",
+		name:       "zero",
+		n:          0,
 	}, {
-		want: fmt.Errorf("aghio: invalid n in LimitReader: -1"),
-		name: "negative",
-		n:    -1,
+		wantErrMsg: "aghio: invalid n in LimitReader: -1",
+		name:       "negative",
+		n:          -1,
 	}}
 
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
 			_, err := LimitReader(nil, tc.n)
-			assert.Equal(t, tc.want, err)
+			testutil.AssertErrorMsg(t, tc.wantErrMsg, err)
 		})
 	}
 }
@@ -73,36 +73,23 @@ func TestLimitedReader_Read(t *testing.T) {
 	}}
 
 	for _, tc := range testCases {
+		readCloser := io.NopCloser(strings.NewReader(tc.rStr))
+		lreader, err := LimitReader(readCloser, tc.limit)
+		require.NoError(t, err)
+		require.NotNil(t, lreader)
+
 		t.Run(tc.name, func(t *testing.T) {
-			readCloser := io.NopCloser(strings.NewReader(tc.rStr))
 			buf := make([]byte, tc.limit+1)
+			n, rerr := lreader.Read(buf)
+			require.Equal(t, rerr, tc.err)
 
-			lreader, err := LimitReader(readCloser, tc.limit)
-			require.NoError(t, err)
-
-			n, err := lreader.Read(buf)
-			require.Equal(t, tc.err, err)
 			assert.Equal(t, tc.want, n)
 		})
 	}
 }
 
 func TestLimitedReader_LimitReachedError(t *testing.T) {
-	testCases := []struct {
-		err  error
-		name string
-		want string
-	}{{
-		err: &LimitReachedError{
-			Limit: 0,
-		},
-		name: "simplest",
-		want: "attempted to read more than 0 bytes",
-	}}
-
-	for _, tc := range testCases {
-		t.Run(tc.name, func(t *testing.T) {
-			assert.Equal(t, tc.want, tc.err.Error())
-		})
-	}
+	testutil.AssertErrorMsg(t, "attempted to read more than 0 bytes", &LimitReachedError{
+		Limit: 0,
+	})
 }
diff --git a/internal/aghnet/systemresolvers_others_test.go b/internal/aghnet/systemresolvers_others_test.go
index f614c960..79abeca2 100644
--- a/internal/aghnet/systemresolvers_others_test.go
+++ b/internal/aghnet/systemresolvers_others_test.go
@@ -79,8 +79,8 @@ func TestSystemResolvers_DialFunc(t *testing.T) {
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
 			conn, err := imp.dialFunc(context.Background(), "", tc.address)
-
 			require.Nil(t, conn)
+
 			assert.ErrorIs(t, err, tc.want)
 		})
 	}
diff --git a/internal/dhcpd/conn_unix_test.go b/internal/dhcpd/conn_unix_test.go
index f3c20805..cbcaa753 100644
--- a/internal/dhcpd/conn_unix_test.go
+++ b/internal/dhcpd/conn_unix_test.go
@@ -5,9 +5,9 @@ package dhcpd
 
 import (
 	"net"
-	"strings"
 	"testing"
 
+	"github.com/AdguardTeam/golibs/testutil"
 	"github.com/google/gopacket"
 	"github.com/google/gopacket/layers"
 	"github.com/insomniacslk/dhcp/dhcpv4"
@@ -45,7 +45,7 @@ func TestDHCPConn_WriteTo_common(t *testing.T) {
 		n, err := conn.WriteTo(nil, &unexpectedAddrType{})
 		require.Error(t, err)
 
-		assert.True(t, strings.Contains(err.Error(), "peer is of unexpected type"))
+		testutil.AssertErrorMsg(t, "peer is of unexpected type *dhcpd.unexpectedAddrType", err)
 		assert.Zero(t, n)
 	})
 }
diff --git a/internal/dhcpd/dhcpd_test.go b/internal/dhcpd/dhcpd_test.go
index 8609481b..b8fc5fa0 100644
--- a/internal/dhcpd/dhcpd_test.go
+++ b/internal/dhcpd/dhcpd_test.go
@@ -68,9 +68,7 @@ func TestDB(t *testing.T) {
 	err = s.dbStore()
 	require.NoError(t, err)
 
-	t.Cleanup(func() {
-		assert.NoError(t, os.Remove(dbFilename))
-	})
+	testutil.CleanupAndRequireSuccess(t, func() (err error) { return os.Remove(dbFilename) })
 
 	err = s.srv4.ResetLeases(nil)
 	require.NoError(t, err)
diff --git a/internal/dhcpd/http_test.go b/internal/dhcpd/http_test.go
index 36a89a6e..120e02a3 100644
--- a/internal/dhcpd/http_test.go
+++ b/internal/dhcpd/http_test.go
@@ -15,7 +15,7 @@ func TestServer_notImplemented(t *testing.T) {
 
 	w := httptest.NewRecorder()
 	r, err := http.NewRequest(http.MethodGet, "/unsupported", nil)
-	require.Nil(t, err)
+	require.NoError(t, err)
 
 	h(w, r)
 	assert.Equal(t, http.StatusNotImplemented, w.Code)
diff --git a/internal/dhcpd/iprange_test.go b/internal/dhcpd/iprange_test.go
index 2579ded9..d3d8c74d 100644
--- a/internal/dhcpd/iprange_test.go
+++ b/internal/dhcpd/iprange_test.go
@@ -4,6 +4,7 @@ import (
 	"net"
 	"testing"
 
+	"github.com/AdguardTeam/golibs/testutil"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -64,14 +65,8 @@ func TestNewIPRange(t *testing.T) {
 
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
-			r, err := newIPRange(tc.start, tc.end)
-			if tc.wantErrMsg == "" {
-				assert.NoError(t, err)
-				assert.NotNil(t, r)
-			} else {
-				require.Error(t, err)
-				assert.Equal(t, tc.wantErrMsg, err.Error())
-			}
+			_, err := newIPRange(tc.start, tc.end)
+			testutil.AssertErrorMsg(t, tc.wantErrMsg, err)
 		})
 	}
 }
diff --git a/internal/dhcpd/nullbool_test.go b/internal/dhcpd/nullbool_test.go
index f1f12e47..32c9f9f4 100644
--- a/internal/dhcpd/nullbool_test.go
+++ b/internal/dhcpd/nullbool_test.go
@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"testing"
 
+	"github.com/AdguardTeam/golibs/testutil"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -45,13 +46,7 @@ func TestNullBool_UnmarshalJSON(t *testing.T) {
 		t.Run(tc.name, func(t *testing.T) {
 			var got nullBool
 			err := got.UnmarshalJSON(tc.data)
-			if tc.wantErrMsg == "" {
-				assert.NoError(t, err)
-			} else {
-				require.Error(t, err)
-
-				assert.Equal(t, tc.wantErrMsg, err.Error())
-			}
+			testutil.AssertErrorMsg(t, tc.wantErrMsg, err)
 
 			assert.Equal(t, tc.want, got)
 		})
diff --git a/internal/dhcpd/options_unix_test.go b/internal/dhcpd/options_unix_test.go
index 5c936b00..6b229f44 100644
--- a/internal/dhcpd/options_unix_test.go
+++ b/internal/dhcpd/options_unix_test.go
@@ -95,6 +95,7 @@ func TestParseOpt(t *testing.T) {
 			opt, err := parseDHCPOption(tc.in)
 			if tc.wantErrMsg != "" {
 				require.Error(t, err)
+
 				assert.Equal(t, tc.wantErrMsg, err.Error())
 
 				return
diff --git a/internal/dhcpd/v4_test.go b/internal/dhcpd/v4_test.go
index 9bed3c60..58e5c27a 100644
--- a/internal/dhcpd/v4_test.go
+++ b/internal/dhcpd/v4_test.go
@@ -9,6 +9,7 @@ import (
 	"testing"
 
 	"github.com/AdguardTeam/golibs/stringutil"
+	"github.com/AdguardTeam/golibs/testutil"
 	"github.com/insomniacslk/dhcp/dhcpv4"
 	"github.com/mdlayher/raw"
 	"github.com/stretchr/testify/assert"
@@ -430,14 +431,7 @@ func TestNormalizeHostname(t *testing.T) {
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
 			got, err := normalizeHostname(tc.hostname)
-			if tc.wantErrMsg == "" {
-				assert.NoError(t, err)
-			} else {
-				require.Error(t, err)
-
-				assert.Equal(t, tc.wantErrMsg, err.Error())
-			}
-
+			testutil.AssertErrorMsg(t, tc.wantErrMsg, err)
 			assert.Equal(t, tc.want, got)
 		})
 	}
diff --git a/internal/dnsforward/clientid_test.go b/internal/dnsforward/clientid_test.go
index f91eaeff..ad7ac43f 100644
--- a/internal/dnsforward/clientid_test.go
+++ b/internal/dnsforward/clientid_test.go
@@ -8,9 +8,9 @@ import (
 	"testing"
 
 	"github.com/AdguardTeam/dnsproxy/proxy"
+	"github.com/AdguardTeam/golibs/testutil"
 	"github.com/lucas-clemente/quic-go"
 	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
 )
 
 // testTLSConn is a tlsConn for tests.
@@ -179,13 +179,7 @@ func TestServer_clientIDFromDNSContext(t *testing.T) {
 			clientID, err := srv.clientIDFromDNSContext(pctx)
 			assert.Equal(t, tc.wantClientID, clientID)
 
-			if tc.wantErrMsg == "" {
-				assert.NoError(t, err)
-			} else {
-				require.Error(t, err)
-
-				assert.Equal(t, tc.wantErrMsg, err.Error())
-			}
+			testutil.AssertErrorMsg(t, tc.wantErrMsg, err)
 		})
 	}
 }
@@ -250,13 +244,7 @@ func TestClientIDFromDNSContextHTTPS(t *testing.T) {
 			clientID, err := clientIDFromDNSContextHTTPS(pctx)
 			assert.Equal(t, tc.wantClientID, clientID)
 
-			if tc.wantErrMsg == "" {
-				assert.NoError(t, err)
-			} else {
-				require.Error(t, err)
-
-				assert.Equal(t, tc.wantErrMsg, err.Error())
-			}
+			testutil.AssertErrorMsg(t, tc.wantErrMsg, err)
 		})
 	}
 }
diff --git a/internal/dnsforward/dnsforward_test.go b/internal/dnsforward/dnsforward_test.go
index a3aa68c6..701d1c5d 100644
--- a/internal/dnsforward/dnsforward_test.go
+++ b/internal/dnsforward/dnsforward_test.go
@@ -24,6 +24,7 @@ import (
 	"github.com/AdguardTeam/dnsproxy/proxy"
 	"github.com/AdguardTeam/dnsproxy/upstream"
 	"github.com/AdguardTeam/golibs/errors"
+	"github.com/AdguardTeam/golibs/testutil"
 	"github.com/AdguardTeam/golibs/timeutil"
 	"github.com/miekg/dns"
 	"github.com/stretchr/testify/assert"
@@ -45,10 +46,7 @@ func startDeferStop(t *testing.T, s *Server) {
 	err := s.Start()
 	require.NoErrorf(t, err, "failed to start server: %s", err)
 
-	t.Cleanup(func() {
-		serr := s.Stop()
-		require.NoErrorf(t, serr, "dns server failed to stop: %s", serr)
-	})
+	testutil.CleanupAndRequireSuccess(t, s.Stop)
 }
 
 func createTestServer(
@@ -1049,9 +1047,7 @@ func TestPTRResponseFromDHCPLeases(t *testing.T) {
 	err = s.Start()
 	require.NoError(t, err)
 
-	t.Cleanup(func() {
-		s.Close()
-	})
+	t.Cleanup(s.Close)
 
 	addr := s.dnsProxy.Addr(proxy.ProtoUDP)
 	req := createTestMessageWithType("34.12.168.192.in-addr.arpa.", dns.TypePTR)
@@ -1131,9 +1127,7 @@ func TestPTRResponseFromHosts(t *testing.T) {
 
 	err = s.Start()
 	require.NoError(t, err)
-	t.Cleanup(func() {
-		s.Close()
-	})
+	t.Cleanup(s.Close)
 
 	subTestFunc := func(t *testing.T) {
 		addr := s.dnsProxy.Addr(proxy.ProtoUDP)
@@ -1197,12 +1191,7 @@ func TestNewServer(t *testing.T) {
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
 			_, err := NewServer(tc.in)
-			if tc.wantErrMsg == "" {
-				assert.NoError(t, err)
-			} else {
-				require.Error(t, err)
-				assert.Equal(t, tc.wantErrMsg, err.Error())
-			}
+			testutil.AssertErrorMsg(t, tc.wantErrMsg, err)
 		})
 	}
 }
diff --git a/internal/dnsforward/dnsrewrite_test.go b/internal/dnsforward/dnsrewrite_test.go
index 92af93aa..347b8f29 100644
--- a/internal/dnsforward/dnsrewrite_test.go
+++ b/internal/dnsforward/dnsrewrite_test.go
@@ -61,8 +61,8 @@ func TestServer_FilterDNSRewrite(t *testing.T) {
 		d := &proxy.DNSContext{}
 
 		err := srv.filterDNSRewrite(req, res, d)
+		require.NoError(t, err)
 
-		require.Nil(t, err)
 		assert.Equal(t, dns.RcodeNameError, d.Res.Rcode)
 	})
 
@@ -72,7 +72,8 @@ func TestServer_FilterDNSRewrite(t *testing.T) {
 		d := &proxy.DNSContext{}
 
 		err := srv.filterDNSRewrite(req, res, d)
-		require.Nil(t, err)
+		require.NoError(t, err)
+
 		assert.Equal(t, dns.RcodeSuccess, d.Res.Rcode)
 		assert.Empty(t, d.Res.Answer)
 	})
@@ -83,7 +84,8 @@ func TestServer_FilterDNSRewrite(t *testing.T) {
 		d := &proxy.DNSContext{}
 
 		err := srv.filterDNSRewrite(req, res, d)
-		require.Nil(t, err)
+		require.NoError(t, err)
+
 		assert.Equal(t, dns.RcodeSuccess, d.Res.Rcode)
 
 		require.Len(t, d.Res.Answer, 1)
@@ -96,7 +98,8 @@ func TestServer_FilterDNSRewrite(t *testing.T) {
 		d := &proxy.DNSContext{}
 
 		err := srv.filterDNSRewrite(req, res, d)
-		require.Nil(t, err)
+		require.NoError(t, err)
+
 		assert.Equal(t, dns.RcodeSuccess, d.Res.Rcode)
 
 		require.Len(t, d.Res.Answer, 1)
@@ -109,7 +112,8 @@ func TestServer_FilterDNSRewrite(t *testing.T) {
 		d := &proxy.DNSContext{}
 
 		err := srv.filterDNSRewrite(req, res, d)
-		require.Nil(t, err)
+		require.NoError(t, err)
+
 		assert.Equal(t, dns.RcodeSuccess, d.Res.Rcode)
 
 		require.Len(t, d.Res.Answer, 1)
@@ -122,7 +126,8 @@ func TestServer_FilterDNSRewrite(t *testing.T) {
 		d := &proxy.DNSContext{}
 
 		err := srv.filterDNSRewrite(req, res, d)
-		require.Nil(t, err)
+		require.NoError(t, err)
+
 		assert.Equal(t, dns.RcodeSuccess, d.Res.Rcode)
 
 		require.Len(t, d.Res.Answer, 1)
@@ -135,7 +140,8 @@ func TestServer_FilterDNSRewrite(t *testing.T) {
 		d := &proxy.DNSContext{}
 
 		err := srv.filterDNSRewrite(req, res, d)
-		require.Nil(t, err)
+		require.NoError(t, err)
+
 		assert.Equal(t, dns.RcodeSuccess, d.Res.Rcode)
 
 		require.Len(t, d.Res.Answer, 1)
@@ -152,7 +158,8 @@ func TestServer_FilterDNSRewrite(t *testing.T) {
 		d := &proxy.DNSContext{}
 
 		err := srv.filterDNSRewrite(req, res, d)
-		require.Nil(t, err)
+		require.NoError(t, err)
+
 		assert.Equal(t, dns.RcodeSuccess, d.Res.Rcode)
 
 		require.Len(t, d.Res.Answer, 1)
@@ -171,7 +178,8 @@ func TestServer_FilterDNSRewrite(t *testing.T) {
 		d := &proxy.DNSContext{}
 
 		err := srv.filterDNSRewrite(req, res, d)
-		require.Nil(t, err)
+		require.NoError(t, err)
+
 		assert.Equal(t, dns.RcodeSuccess, d.Res.Rcode)
 
 		require.Len(t, d.Res.Answer, 1)
@@ -190,7 +198,8 @@ func TestServer_FilterDNSRewrite(t *testing.T) {
 		d := &proxy.DNSContext{}
 
 		err := srv.filterDNSRewrite(req, res, d)
-		require.Nil(t, err)
+		require.NoError(t, err)
+
 		assert.Equal(t, dns.RcodeSuccess, d.Res.Rcode)
 
 		require.Len(t, d.Res.Answer, 1)
diff --git a/internal/dnsforward/http_test.go b/internal/dnsforward/http_test.go
index cb6fa924..f411a1b0 100644
--- a/internal/dnsforward/http_test.go
+++ b/internal/dnsforward/http_test.go
@@ -14,6 +14,7 @@ import (
 
 	"github.com/AdguardTeam/AdGuardHome/internal/aghnet"
 	"github.com/AdguardTeam/AdGuardHome/internal/filtering"
+	"github.com/AdguardTeam/golibs/testutil"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -38,9 +39,7 @@ func loadTestData(t *testing.T, casesFileName string, cases interface{}) {
 	var f *os.File
 	f, err := os.Open(filepath.Join("testdata", casesFileName))
 	require.NoError(t, err)
-	t.Cleanup(func() {
-		require.NoError(t, f.Close())
-	})
+	testutil.CleanupAndRequireSuccess(t, f.Close)
 
 	err = json.NewDecoder(f).Decode(cases)
 	require.NoError(t, err)
@@ -69,10 +68,8 @@ func TestDNSForwardHTTP_handleGetConfig(t *testing.T) {
 	s := createTestServer(t, filterConf, forwardConf, nil)
 	s.sysResolvers = &fakeSystemResolvers{}
 
-	require.Nil(t, s.Start())
-	t.Cleanup(func() {
-		require.Nil(t, s.Stop())
-	})
+	require.NoError(t, s.Start())
+	testutil.CleanupAndRequireSuccess(t, s.Stop)
 
 	defaultConf := s.conf
 
@@ -147,10 +144,8 @@ func TestDNSForwardHTTP_handleSetConfig(t *testing.T) {
 	defaultConf := s.conf
 
 	err := s.Start()
-	assert.Nil(t, err)
-	t.Cleanup(func() {
-		assert.Nil(t, s.Stop())
-	})
+	assert.NoError(t, err)
+	testutil.CleanupAndRequireSuccess(t, s.Stop)
 
 	w := httptest.NewRecorder()
 
@@ -221,14 +216,12 @@ func TestDNSForwardHTTP_handleSetConfig(t *testing.T) {
 		require.True(t, ok)
 
 		t.Run(tc.name, func(t *testing.T) {
-			t.Cleanup(func() {
-				s.conf = defaultConf
-			})
+			t.Cleanup(func() { s.conf = defaultConf })
 
 			rBody := io.NopCloser(bytes.NewReader(caseData.Req))
 			var r *http.Request
 			r, err = http.NewRequest(http.MethodPost, "http://example.com", rBody)
-			require.Nil(t, err)
+			require.NoError(t, err)
 
 			s.handleSetConfig(w, r)
 			assert.Equal(t, tc.wantSet, strings.TrimSuffix(w.Body.String(), "\n"))
diff --git a/internal/dnsforward/stats_test.go b/internal/dnsforward/stats_test.go
index 64171288..92985fd4 100644
--- a/internal/dnsforward/stats_test.go
+++ b/internal/dnsforward/stats_test.go
@@ -157,7 +157,7 @@ func TestProcessQueryLogsAndStats(t *testing.T) {
 	}}
 
 	ups, err := upstream.AddressToUpstream("1.1.1.1", nil)
-	require.Nil(t, err)
+	require.NoError(t, err)
 
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
diff --git a/internal/home/auth_test.go b/internal/home/auth_test.go
index f6b2b106..6a2ebea7 100644
--- a/internal/home/auth_test.go
+++ b/internal/home/auth_test.go
@@ -13,6 +13,7 @@ import (
 	"time"
 
 	"github.com/AdguardTeam/AdGuardHome/internal/aghtest"
+	"github.com/AdguardTeam/golibs/testutil"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -24,19 +25,17 @@ func TestMain(m *testing.M) {
 func TestNewSessionToken(t *testing.T) {
 	// Successful case.
 	token, err := newSessionToken()
-	require.Nil(t, err)
+	require.NoError(t, err)
 	assert.Len(t, token, sessionTokenSize)
 
 	// Break the rand.Reader.
 	prevReader := rand.Reader
-	t.Cleanup(func() {
-		rand.Reader = prevReader
-	})
+	t.Cleanup(func() { rand.Reader = prevReader })
 	rand.Reader = &bytes.Buffer{}
 
 	// Unsuccessful case.
 	token, err = newSessionToken()
-	require.NotNil(t, err)
+	require.Error(t, err)
 	assert.Empty(t, token)
 }
 
@@ -58,7 +57,7 @@ func TestAuth(t *testing.T) {
 	a.RemoveSession("notfound")
 
 	sess, err := newSessionToken()
-	assert.Nil(t, err)
+	require.NoError(t, err)
 	sessStr := hex.EncodeToString(sess)
 
 	now := time.Now().UTC().Unix()
@@ -152,7 +151,7 @@ func TestAuthHTTP(t *testing.T) {
 
 	// perform login
 	cookie, err := Context.auth.httpCookie(loginJSON{Name: "name", Password: "password"}, "")
-	assert.Nil(t, err)
+	require.NoError(t, err)
 	assert.NotEmpty(t, cookie)
 
 	// get /
@@ -251,12 +250,7 @@ func TestRealIP(t *testing.T) {
 			ip, err := realIP(r)
 			assert.Equal(t, tc.wantIP, ip)
 
-			if tc.wantErrMsg == "" {
-				assert.NoError(t, err)
-			} else {
-				require.Error(t, err)
-				assert.Equal(t, tc.wantErrMsg, err.Error())
-			}
+			testutil.AssertErrorMsg(t, tc.wantErrMsg, err)
 		})
 	}
 }
diff --git a/internal/home/authglinet_test.go b/internal/home/authglinet_test.go
index 46a1bc21..ef20ebf8 100644
--- a/internal/home/authglinet_test.go
+++ b/internal/home/authglinet_test.go
@@ -15,21 +15,19 @@ func TestAuthGL(t *testing.T) {
 	dir := t.TempDir()
 
 	GLMode = true
-	t.Cleanup(func() {
-		GLMode = false
-	})
+	t.Cleanup(func() { GLMode = false })
 	glFilePrefix = dir + "/gl_token_"
 
 	data := make([]byte, 4)
 	aghos.NativeEndian.PutUint32(data, 1)
 
-	require.Nil(t, os.WriteFile(glFilePrefix+"test", data, 0o644))
+	require.NoError(t, os.WriteFile(glFilePrefix+"test", data, 0o644))
 	assert.False(t, glCheckToken("test"))
 
 	data = make([]byte, 4)
 	aghos.NativeEndian.PutUint32(data, uint32(time.Now().UTC().Unix()+60))
 
-	require.Nil(t, os.WriteFile(glFilePrefix+"test", data, 0o644))
+	require.NoError(t, os.WriteFile(glFilePrefix+"test", data, 0o644))
 	r, _ := http.NewRequest(http.MethodGet, "http://localhost/", nil)
 	r.AddCookie(&http.Cookie{Name: glCookieName, Value: "test"})
 	assert.True(t, glProcessCookie(r))
diff --git a/internal/home/clients_test.go b/internal/home/clients_test.go
index 392a7545..93bf3360 100644
--- a/internal/home/clients_test.go
+++ b/internal/home/clients_test.go
@@ -290,7 +290,9 @@ func TestClientsAddExisting(t *testing.T) {
 
 		clients.dhcpServer, err = dhcpd.Create(config)
 		require.NoError(t, err)
-
+		// TODO(e.burkov):  leases.db isn't created on Windows so removing it
+		// causes an error.  Split the test to make it run properly on different
+		// operating systems.
 		t.Cleanup(func() { _ = os.Remove("leases.db") })
 
 		err = clients.dhcpServer.AddStaticLease(&dhcpd.Lease{
@@ -309,8 +311,7 @@ func TestClientsAddExisting(t *testing.T) {
 		require.NoError(t, err)
 		assert.True(t, ok)
 
-		// Add a new client with the IP from the first client's IP
-		// range.
+		// Add a new client with the IP from the first client's IP range.
 		ok, err = clients.Add(&Client{
 			IDs:  []string{"2.2.2.2"},
 			Name: "client3",
diff --git a/internal/home/filter_test.go b/internal/home/filter_test.go
index 0aa8d3b1..08290562 100644
--- a/internal/home/filter_test.go
+++ b/internal/home/filter_test.go
@@ -12,6 +12,7 @@ import (
 	"time"
 
 	"github.com/AdguardTeam/golibs/netutil"
+	"github.com/AdguardTeam/golibs/testutil"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -21,7 +22,7 @@ const testFltsFileName = "1.txt"
 func testStartFilterListener(t *testing.T, fltContent *[]byte) (l net.Listener) {
 	t.Helper()
 
-	h := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+	h := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
 		n, werr := w.Write(*fltContent)
 		require.NoError(t, werr)
 		require.Equal(t, len(*fltContent), n)
@@ -34,9 +35,7 @@ func testStartFilterListener(t *testing.T, fltContent *[]byte) (l net.Listener)
 	go func() {
 		_ = http.Serve(l, h)
 	}()
-	t.Cleanup(func() {
-		require.NoError(t, l.Close())
-	})
+	testutil.CleanupAndRequireSuccess(t, l.Close)
 
 	return l
 }
@@ -100,9 +99,7 @@ func TestFilters(t *testing.T) {
 
 	t.Run("refresh_actually", func(t *testing.T) {
 		fltContent = []byte(`||example.com^`)
-		t.Cleanup(func() {
-			fltContent = []byte(content)
-		})
+		t.Cleanup(func() { fltContent = []byte(content) })
 
 		updateAndAssert(t, require.True, 1)
 	})
diff --git a/internal/home/middlewares_test.go b/internal/home/middlewares_test.go
index 8c76f73c..96da52fb 100644
--- a/internal/home/middlewares_test.go
+++ b/internal/home/middlewares_test.go
@@ -46,7 +46,7 @@ func TestLimitRequestBody(t *testing.T) {
 			var b []byte
 			b, *err = io.ReadAll(r.Body)
 			_, werr := w.Write(b)
-			require.Nil(t, werr)
+			require.NoError(t, werr)
 		})
 	}
 
diff --git a/internal/home/mobileconfig_test.go b/internal/home/mobileconfig_test.go
index 03b16611..5230a2ac 100644
--- a/internal/home/mobileconfig_test.go
+++ b/internal/home/mobileconfig_test.go
@@ -153,7 +153,6 @@ func TestHandleMobileConfigDoT(t *testing.T) {
 
 		handleMobileConfigDoT(w, r)
 		assert.Equal(t, http.StatusInternalServerError, w.Code)
-
 		assert.JSONEq(t, w.Body.String(), b.String())
 	})
 
diff --git a/internal/home/options_test.go b/internal/home/options_test.go
index ee4cc4a5..b189f045 100644
--- a/internal/home/options_test.go
+++ b/internal/home/options_test.go
@@ -13,7 +13,7 @@ func testParseOK(t *testing.T, ss ...string) options {
 	t.Helper()
 
 	o, _, err := parse("", ss)
-	require.Nil(t, err)
+	require.NoError(t, err)
 
 	return o
 }
@@ -22,7 +22,7 @@ func testParseErr(t *testing.T, descr string, ss ...string) {
 	t.Helper()
 
 	_, _, err := parse("", ss)
-	require.NotNilf(t, err, "expected an error because %s but no error returned", descr)
+	require.Error(t, err)
 }
 
 func testParseParamMissing(t *testing.T, param string) {
diff --git a/internal/home/upgrade_test.go b/internal/home/upgrade_test.go
index c5fe0bbb..171ce3b2 100644
--- a/internal/home/upgrade_test.go
+++ b/internal/home/upgrade_test.go
@@ -4,6 +4,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/AdguardTeam/golibs/testutil"
 	"github.com/AdguardTeam/golibs/timeutil"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -333,8 +334,7 @@ func TestUpgradeSchema9to10(t *testing.T) {
 			err := upgradeSchema9to10(conf)
 
 			if tc.wantErr != "" {
-				require.Error(t, err)
-				assert.Equal(t, tc.wantErr, err.Error())
+				testutil.AssertErrorMsg(t, tc.wantErr, err)
 
 				return
 			}
@@ -366,8 +366,7 @@ func TestUpgradeSchema9to10(t *testing.T) {
 			"dns": ultimateAns,
 		})
 
-		require.Error(t, err)
-		assert.Equal(t, "unexpected type of dns: int", err.Error())
+		testutil.AssertErrorMsg(t, "unexpected type of dns: int", err)
 	})
 }
 
@@ -448,6 +447,7 @@ func TestUpgradeSchema11to12(t *testing.T) {
 
 			if tc.wantErr != "" {
 				require.Error(t, err)
+
 				assert.Equal(t, tc.wantErr, err.Error())
 
 				return
@@ -482,8 +482,7 @@ func TestUpgradeSchema11to12(t *testing.T) {
 			"dns": 0,
 		})
 
-		require.Error(t, err)
-		assert.Equal(t, "unexpected type of dns: int", err.Error())
+		testutil.AssertErrorMsg(t, "unexpected type of dns: int", err)
 	})
 
 	t.Run("no_field", func(t *testing.T) {
diff --git a/internal/querylog/decode_test.go b/internal/querylog/decode_test.go
index 9aebfe41..3848d344 100644
--- a/internal/querylog/decode_test.go
+++ b/internal/querylog/decode_test.go
@@ -14,6 +14,7 @@ import (
 	"github.com/AdguardTeam/urlfilter/rules"
 	"github.com/miekg/dns"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestDecodeLogEntry(t *testing.T) {
@@ -45,7 +46,7 @@ func TestDecodeLogEntry(t *testing.T) {
 			`"Elapsed":837429}`
 
 		ans, err := base64.StdEncoding.DecodeString(ansStr)
-		assert.Nil(t, err)
+		require.NoError(t, err)
 
 		want := &logEntry{
 			IP:          net.IPv4(127, 0, 0, 1),
diff --git a/internal/querylog/qlog_test.go b/internal/querylog/qlog_test.go
index b6617cd3..1990d08f 100644
--- a/internal/querylog/qlog_test.go
+++ b/internal/querylog/qlog_test.go
@@ -35,13 +35,13 @@ func TestQueryLog(t *testing.T) {
 	// Add disk entries.
 	addEntry(l, "example.org", net.IPv4(1, 1, 1, 1), net.IPv4(2, 2, 2, 1))
 	// Write to disk (first file).
-	require.Nil(t, l.flushLogBuffer(true))
+	require.NoError(t, l.flushLogBuffer(true))
 	// Start writing to the second file.
-	require.Nil(t, l.rotate())
+	require.NoError(t, l.rotate())
 	// Add disk entries.
 	addEntry(l, "example.org", net.IPv4(1, 1, 1, 2), net.IPv4(2, 2, 2, 2))
 	// Write to disk.
-	require.Nil(t, l.flushLogBuffer(true))
+	require.NoError(t, l.flushLogBuffer(true))
 	// Add memory entries.
 	addEntry(l, "test.example.org", net.IPv4(1, 1, 1, 3), net.IPv4(2, 2, 2, 3))
 	addEntry(l, "example.com", net.IPv4(1, 1, 1, 4), net.IPv4(2, 2, 2, 4))
@@ -144,7 +144,7 @@ func TestQueryLogOffsetLimit(t *testing.T) {
 		addEntry(l, secondPageDomain, net.IPv4(1, 1, 1, 1), net.IPv4(2, 2, 2, 1))
 	}
 	// Write them to the first file.
-	require.Nil(t, l.flushLogBuffer(true))
+	require.NoError(t, l.flushLogBuffer(true))
 	// Add more to the in-memory part of log.
 	for i := 0; i < entNum; i++ {
 		addEntry(l, firstPageDomain, net.IPv4(1, 1, 1, 1), net.IPv4(2, 2, 2, 1))
@@ -215,7 +215,7 @@ func TestQueryLogMaxFileScanEntries(t *testing.T) {
 		addEntry(l, "example.org", net.IPv4(1, 1, 1, 1), net.IPv4(2, 2, 2, 1))
 	}
 	// Write them to disk.
-	require.Nil(t, l.flushLogBuffer(true))
+	require.NoError(t, l.flushLogBuffer(true))
 
 	params := newSearchParams()
 
@@ -300,7 +300,7 @@ func assertLogEntry(t *testing.T, entry *logEntry, host string, answer, client n
 	assert.Equal(t, "IN", entry.QClass)
 
 	msg := &dns.Msg{}
-	require.Nil(t, msg.Unpack(entry.Answer))
+	require.NoError(t, msg.Unpack(entry.Answer))
 	require.Len(t, msg.Answer, 1)
 
 	ip := proxyutil.GetIPFromDNSRecord(msg.Answer[0]).To16()
diff --git a/internal/querylog/qlogfile_test.go b/internal/querylog/qlogfile_test.go
index 5e82ce72..b85eb049 100644
--- a/internal/querylog/qlogfile_test.go
+++ b/internal/querylog/qlogfile_test.go
@@ -12,6 +12,7 @@ import (
 	"time"
 
 	"github.com/AdguardTeam/golibs/errors"
+	"github.com/AdguardTeam/golibs/testutil"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -80,11 +81,10 @@ func newTestQLogFile(t *testing.T, linesNum int) (file *QLogFile) {
 
 	// Create the new QLogFile instance.
 	file, err := NewQLogFile(testFile)
-	require.Nil(t, err)
+	require.NoError(t, err)
+
 	assert.NotNil(t, file)
-	t.Cleanup(func() {
-		assert.Nil(t, file.Close())
-	})
+	testutil.CleanupAndRequireSuccess(t, file.Close)
 
 	return file
 }
@@ -107,7 +107,7 @@ func TestQLogFile_ReadNext(t *testing.T) {
 
 			// Calculate the expected position.
 			fileInfo, err := q.file.Stat()
-			require.Nil(t, err)
+			require.NoError(t, err)
 			var expPos int64
 			if expPos = fileInfo.Size(); expPos > 0 {
 				expPos--
@@ -115,7 +115,7 @@ func TestQLogFile_ReadNext(t *testing.T) {
 
 			// Seek to the start.
 			pos, err := q.SeekStart()
-			require.Nil(t, err)
+			require.NoError(t, err)
 			require.EqualValues(t, expPos, pos)
 
 			var read int
@@ -170,17 +170,17 @@ func TestQLogFile_SeekTS_good(t *testing.T) {
 		for _, tc := range testCases {
 			t.Run(l.name+"_"+tc.name, func(t *testing.T) {
 				line, err := getQLogFileLine(q, tc.line)
-				require.Nil(t, err)
+				require.NoError(t, err)
 				ts := readQLogTimestamp(line)
 				assert.NotEqualValues(t, 0, ts)
 
 				// Try seeking to that line now.
 				pos, _, err := q.SeekTS(ts)
-				require.Nil(t, err)
+				require.NoError(t, err)
 				assert.NotEqualValues(t, 0, pos)
 
 				testLine, err := q.ReadNext()
-				require.Nil(t, err)
+				require.NoError(t, err)
 				assert.Equal(t, line, testLine)
 			})
 		}
@@ -220,7 +220,7 @@ func TestQLogFile_SeekTS_bad(t *testing.T) {
 		testCases[1].ts = lateTS.UnixNano()
 
 		line, err := getQLogFileLine(q, l.num/2)
-		require.Nil(t, err)
+		require.NoError(t, err)
 		testCases[2].ts = readQLogTimestamp(line) - 1
 
 		for _, tc := range testCases {
@@ -230,7 +230,8 @@ func TestQLogFile_SeekTS_bad(t *testing.T) {
 				var depth int
 				_, depth, err = q.SeekTS(tc.ts)
 				assert.NotEmpty(t, l.num)
-				require.NotNil(t, err)
+				require.Error(t, err)
+
 				if tc.leq {
 					assert.LessOrEqual(t, depth, int(math.Log2(float64(l.num))+3))
 				}
@@ -260,19 +261,19 @@ func TestQLogFile(t *testing.T) {
 
 	// Seek to the start.
 	pos, err := q.SeekStart()
-	require.Nil(t, err)
+	require.NoError(t, err)
 	assert.Greater(t, pos, int64(0))
 
 	// Read first line.
 	line, err := q.ReadNext()
-	require.Nil(t, err)
+	require.NoError(t, err)
 	assert.Contains(t, line, "0.0.0.2")
 	assert.True(t, strings.HasPrefix(line, "{"), line)
 	assert.True(t, strings.HasSuffix(line, "}"), line)
 
 	// Read second line.
 	line, err = q.ReadNext()
-	require.Nil(t, err)
+	require.NoError(t, err)
 	assert.EqualValues(t, 0, q.position)
 	assert.Contains(t, line, "0.0.0.1")
 	assert.True(t, strings.HasPrefix(line, "{"), line)
@@ -286,19 +287,15 @@ func TestQLogFile(t *testing.T) {
 
 func NewTestQLogFileData(t *testing.T, data string) (file *QLogFile) {
 	f, err := os.CreateTemp(t.TempDir(), "*.txt")
-	require.Nil(t, err)
-	t.Cleanup(func() {
-		assert.Nil(t, f.Close())
-	})
+	require.NoError(t, err)
+	testutil.CleanupAndRequireSuccess(t, f.Close)
 
 	_, err = f.WriteString(data)
-	require.Nil(t, err)
+	require.NoError(t, err)
 
 	file, err = NewQLogFile(f.Name())
-	require.Nil(t, err)
-	t.Cleanup(func() {
-		assert.Nil(t, file.Close())
-	})
+	require.NoError(t, err)
+	testutil.CleanupAndRequireSuccess(t, file.Close)
 
 	return file
 }
diff --git a/internal/querylog/qlogreader_test.go b/internal/querylog/qlogreader_test.go
index 060adbca..564508f7 100644
--- a/internal/querylog/qlogreader_test.go
+++ b/internal/querylog/qlogreader_test.go
@@ -5,6 +5,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/AdguardTeam/golibs/testutil"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -18,12 +19,10 @@ func newTestQLogReader(t *testing.T, filesNum, linesNum int) (reader *QLogReader
 
 	// Create the new QLogReader instance.
 	reader, err := NewQLogReader(testFiles)
-	require.Nil(t, err)
+	require.NoError(t, err)
 
 	assert.NotNil(t, reader)
-	t.Cleanup(func() {
-		assert.Nil(t, reader.Close())
-	})
+	testutil.CleanupAndRequireSuccess(t, reader.Close)
 
 	return reader
 }
@@ -53,7 +52,7 @@ func TestQLogReader(t *testing.T) {
 
 			// Seek to the start.
 			err := r.SeekStart()
-			require.Nil(t, err)
+			require.NoError(t, err)
 
 			// Read everything.
 			var read int
@@ -112,7 +111,7 @@ func TestQLogReader_Seek(t *testing.T) {
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
 			ts, err := time.Parse(time.RFC3339Nano, tc.time)
-			require.Nil(t, err)
+			require.NoError(t, err)
 
 			err = r.SeekTS(ts.UnixNano())
 			assert.ErrorIs(t, err, tc.want)
@@ -142,11 +141,11 @@ func TestQLogReader_ReadNext(t *testing.T) {
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
 			err := r.SeekStart()
-			require.Nil(t, err)
+			require.NoError(t, err)
 
 			for i := 1; i < tc.start; i++ {
 				_, err = r.ReadNext()
-				require.Nil(t, err)
+				require.NoError(t, err)
 			}
 
 			_, err = r.ReadNext()
diff --git a/internal/stats/stats_test.go b/internal/stats/stats_test.go
index e58f198c..70b71db8 100644
--- a/internal/stats/stats_test.go
+++ b/internal/stats/stats_test.go
@@ -8,6 +8,7 @@ import (
 	"testing"
 
 	"github.com/AdguardTeam/AdGuardHome/internal/aghtest"
+	"github.com/AdguardTeam/golibs/testutil"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -37,11 +38,12 @@ func TestStats(t *testing.T) {
 	}
 
 	s, err := createObject(conf)
-	require.Nil(t, err)
-	t.Cleanup(func() {
+	require.NoError(t, err)
+	testutil.CleanupAndRequireSuccess(t, func() (err error) {
 		s.clear()
 		s.Close()
-		assert.Nil(t, os.Remove(conf.Filename))
+
+		return os.Remove(conf.Filename)
 	})
 
 	s.Update(Entry{
@@ -109,10 +111,11 @@ func TestLargeNumbers(t *testing.T) {
 		UnitID:    newID,
 	}
 	s, err := createObject(conf)
-	require.Nil(t, err)
-	t.Cleanup(func() {
+	require.NoError(t, err)
+	testutil.CleanupAndRequireSuccess(t, func() (err error) {
 		s.Close()
-		assert.Nil(t, os.Remove(conf.Filename))
+
+		return os.Remove(conf.Filename)
 	})
 
 	// Number of distinct clients and domains every hour.
diff --git a/internal/updater/updater_test.go b/internal/updater/updater_test.go
index 4393d074..3a29d277 100644
--- a/internal/updater/updater_test.go
+++ b/internal/updater/updater_test.go
@@ -12,7 +12,9 @@ import (
 
 	"github.com/AdguardTeam/AdGuardHome/internal/aghtest"
 	"github.com/AdguardTeam/AdGuardHome/internal/version"
+	"github.com/AdguardTeam/golibs/testutil"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 // TODO(a.garipov): Rewrite these tests.
@@ -67,7 +69,7 @@ func TestUpdateGetVersion(t *testing.T) {
 }`
 
 	l, lport := startHTTPServer(jsonData)
-	t.Cleanup(func() { assert.Nil(t, l.Close()) })
+	testutil.CleanupAndRequireSuccess(t, l.Close)
 
 	u := NewUpdater(&Config{
 		Client:  &http.Client{},
@@ -85,7 +87,8 @@ func TestUpdateGetVersion(t *testing.T) {
 	u.versionCheckURL = fakeURL.String()
 
 	info, err := u.VersionInfo(false)
-	assert.Nil(t, err)
+	require.NoError(t, err)
+
 	assert.Equal(t, "v0.103.0-beta.2", info.NewVersion)
 	assert.Equal(t, "AdGuard Home v0.103.0-beta.2 is now available!", info.Announcement)
 	assert.Equal(t, "https://github.com/AdguardTeam/AdGuardHome/internal/releases", info.AnnouncementURL)
@@ -96,22 +99,23 @@ func TestUpdateGetVersion(t *testing.T) {
 
 	// check cached
 	_, err = u.VersionInfo(false)
-	assert.Nil(t, err)
+	require.NoError(t, err)
 }
 
 func TestUpdate(t *testing.T) {
 	wd := t.TempDir()
 
-	assert.Nil(t, os.WriteFile(filepath.Join(wd, "AdGuardHome"), []byte("AdGuardHome"), 0o755))
-	assert.Nil(t, os.WriteFile(filepath.Join(wd, "README.md"), []byte("README.md"), 0o644))
-	assert.Nil(t, os.WriteFile(filepath.Join(wd, "LICENSE.txt"), []byte("LICENSE.txt"), 0o644))
-	assert.Nil(t, os.WriteFile(filepath.Join(wd, "AdGuardHome.yaml"), []byte("AdGuardHome.yaml"), 0o644))
+	require.NoError(t, os.WriteFile(filepath.Join(wd, "AdGuardHome"), []byte("AdGuardHome"), 0o755))
+	require.NoError(t, os.WriteFile(filepath.Join(wd, "README.md"), []byte("README.md"), 0o644))
+	require.NoError(t, os.WriteFile(filepath.Join(wd, "LICENSE.txt"), []byte("LICENSE.txt"), 0o644))
+	require.NoError(t, os.WriteFile(filepath.Join(wd, "AdGuardHome.yaml"), []byte("AdGuardHome.yaml"), 0o644))
 
 	// start server for returning package file
 	pkgData, err := os.ReadFile("testdata/AdGuardHome.tar.gz")
-	assert.Nil(t, err)
+	require.NoError(t, err)
+
 	l, lport := startHTTPServer(string(pkgData))
-	t.Cleanup(func() { assert.Nil(t, l.Close()) })
+	testutil.CleanupAndRequireSuccess(t, l.Close)
 
 	u := NewUpdater(&Config{
 		Client:  &http.Client{},
@@ -129,56 +133,66 @@ func TestUpdate(t *testing.T) {
 	u.newVersion = "v0.103.1"
 	u.packageURL = fakeURL.String()
 
-	assert.Nil(t, u.prepare())
+	require.NoError(t, u.prepare())
+
 	u.currentExeName = filepath.Join(wd, "AdGuardHome")
-	assert.Nil(t, u.downloadPackageFile(u.packageURL, u.packageName))
-	assert.Nil(t, u.unpack())
-	// assert.Nil(t, u.check())
-	assert.Nil(t, u.backup())
-	assert.Nil(t, u.replace())
+
+	require.NoError(t, u.downloadPackageFile(u.packageURL, u.packageName))
+	require.NoError(t, u.unpack())
+
+	// require.NoError(t, u.check())
+	require.NoError(t, u.backup())
+	require.NoError(t, u.replace())
+
 	u.clean()
 
 	// check backup files
 	d, err := os.ReadFile(filepath.Join(wd, "agh-backup", "AdGuardHome.yaml"))
-	assert.Nil(t, err)
+	require.NoError(t, err)
+
 	assert.Equal(t, "AdGuardHome.yaml", string(d))
 
 	d, err = os.ReadFile(filepath.Join(wd, "agh-backup", "AdGuardHome"))
-	assert.Nil(t, err)
+	require.NoError(t, err)
+
 	assert.Equal(t, "AdGuardHome", string(d))
 
 	// check updated files
 	d, err = os.ReadFile(filepath.Join(wd, "AdGuardHome"))
-	assert.Nil(t, err)
+	require.NoError(t, err)
+
 	assert.Equal(t, "1", string(d))
 
 	d, err = os.ReadFile(filepath.Join(wd, "README.md"))
-	assert.Nil(t, err)
+	require.NoError(t, err)
+
 	assert.Equal(t, "2", string(d))
 
 	d, err = os.ReadFile(filepath.Join(wd, "LICENSE.txt"))
-	assert.Nil(t, err)
+	require.NoError(t, err)
+
 	assert.Equal(t, "3", string(d))
 
 	d, err = os.ReadFile(filepath.Join(wd, "AdGuardHome.yaml"))
-	assert.Nil(t, err)
+	require.NoError(t, err)
+
 	assert.Equal(t, "AdGuardHome.yaml", string(d))
 }
 
 func TestUpdateWindows(t *testing.T) {
 	wd := t.TempDir()
 
-	assert.Nil(t, os.WriteFile(filepath.Join(wd, "AdGuardHome.exe"), []byte("AdGuardHome.exe"), 0o755))
-	assert.Nil(t, os.WriteFile(filepath.Join(wd, "README.md"), []byte("README.md"), 0o644))
-	assert.Nil(t, os.WriteFile(filepath.Join(wd, "LICENSE.txt"), []byte("LICENSE.txt"), 0o644))
-	assert.Nil(t, os.WriteFile(filepath.Join(wd, "AdGuardHome.yaml"), []byte("AdGuardHome.yaml"), 0o644))
+	require.NoError(t, os.WriteFile(filepath.Join(wd, "AdGuardHome.exe"), []byte("AdGuardHome.exe"), 0o755))
+	require.NoError(t, os.WriteFile(filepath.Join(wd, "README.md"), []byte("README.md"), 0o644))
+	require.NoError(t, os.WriteFile(filepath.Join(wd, "LICENSE.txt"), []byte("LICENSE.txt"), 0o644))
+	require.NoError(t, os.WriteFile(filepath.Join(wd, "AdGuardHome.yaml"), []byte("AdGuardHome.yaml"), 0o644))
 
 	// start server for returning package file
 	pkgData, err := os.ReadFile("testdata/AdGuardHome.zip")
-	assert.Nil(t, err)
+	require.NoError(t, err)
 
 	l, lport := startHTTPServer(string(pkgData))
-	t.Cleanup(func() { assert.Nil(t, l.Close()) })
+	testutil.CleanupAndRequireSuccess(t, l.Close)
 
 	u := NewUpdater(&Config{
 		Client:  &http.Client{},
@@ -197,39 +211,48 @@ func TestUpdateWindows(t *testing.T) {
 	u.newVersion = "v0.103.1"
 	u.packageURL = fakeURL.String()
 
-	assert.Nil(t, u.prepare())
+	require.NoError(t, u.prepare())
+
 	u.currentExeName = filepath.Join(wd, "AdGuardHome.exe")
-	assert.Nil(t, u.downloadPackageFile(u.packageURL, u.packageName))
-	assert.Nil(t, u.unpack())
+
+	require.NoError(t, u.downloadPackageFile(u.packageURL, u.packageName))
+	require.NoError(t, u.unpack())
 	// assert.Nil(t, u.check())
-	assert.Nil(t, u.backup())
-	assert.Nil(t, u.replace())
+	require.NoError(t, u.backup())
+	require.NoError(t, u.replace())
+
 	u.clean()
 
 	// check backup files
 	d, err := os.ReadFile(filepath.Join(wd, "agh-backup", "AdGuardHome.yaml"))
-	assert.Nil(t, err)
+	require.NoError(t, err)
+
 	assert.Equal(t, "AdGuardHome.yaml", string(d))
 
 	d, err = os.ReadFile(filepath.Join(wd, "agh-backup", "AdGuardHome.exe"))
-	assert.Nil(t, err)
+	require.NoError(t, err)
+
 	assert.Equal(t, "AdGuardHome.exe", string(d))
 
 	// check updated files
 	d, err = os.ReadFile(filepath.Join(wd, "AdGuardHome.exe"))
-	assert.Nil(t, err)
+	require.NoError(t, err)
+
 	assert.Equal(t, "1", string(d))
 
 	d, err = os.ReadFile(filepath.Join(wd, "README.md"))
-	assert.Nil(t, err)
+	require.NoError(t, err)
+
 	assert.Equal(t, "2", string(d))
 
 	d, err = os.ReadFile(filepath.Join(wd, "LICENSE.txt"))
-	assert.Nil(t, err)
+	require.NoError(t, err)
+
 	assert.Equal(t, "3", string(d))
 
 	d, err = os.ReadFile(filepath.Join(wd, "AdGuardHome.yaml"))
-	assert.Nil(t, err)
+	require.NoError(t, err)
+
 	assert.Equal(t, "AdGuardHome.yaml", string(d))
 }
 
@@ -243,7 +266,7 @@ func TestUpdater_VersionInto_ARM(t *testing.T) {
 }`
 
 	l, lport := startHTTPServer(jsonData)
-	t.Cleanup(func() { assert.Nil(t, l.Close()) })
+	testutil.CleanupAndRequireSuccess(t, l.Close)
 
 	u := NewUpdater(&Config{
 		Client:  &http.Client{},
@@ -262,7 +285,8 @@ func TestUpdater_VersionInto_ARM(t *testing.T) {
 	u.versionCheckURL = fakeURL.String()
 
 	info, err := u.VersionInfo(false)
-	assert.Nil(t, err)
+	require.NoError(t, err)
+
 	assert.Equal(t, "v0.103.0-beta.2", info.NewVersion)
 	assert.Equal(t, "AdGuard Home v0.103.0-beta.2 is now available!", info.Announcement)
 	assert.Equal(t, "https://github.com/AdguardTeam/AdGuardHome/internal/releases", info.AnnouncementURL)
@@ -282,7 +306,7 @@ func TestUpdater_VersionInto_MIPS(t *testing.T) {
 }`
 
 	l, lport := startHTTPServer(jsonData)
-	t.Cleanup(func() { assert.Nil(t, l.Close()) })
+	testutil.CleanupAndRequireSuccess(t, l.Close)
 
 	u := NewUpdater(&Config{
 		Client:  &http.Client{},
@@ -301,7 +325,8 @@ func TestUpdater_VersionInto_MIPS(t *testing.T) {
 	u.versionCheckURL = fakeURL.String()
 
 	info, err := u.VersionInfo(false)
-	assert.Nil(t, err)
+	require.NoError(t, err)
+
 	assert.Equal(t, "v0.103.0-beta.2", info.NewVersion)
 	assert.Equal(t, "AdGuard Home v0.103.0-beta.2 is now available!", info.Announcement)
 	assert.Equal(t, "https://github.com/AdguardTeam/AdGuardHome/internal/releases", info.AnnouncementURL)