diff --git a/testing/scenarios/policy_test.go b/testing/scenarios/policy_test.go
index 1e8aafea..644b313c 100644
--- a/testing/scenarios/policy_test.go
+++ b/testing/scenarios/policy_test.go
@@ -249,7 +249,7 @@ func TestZeroBuffer(t *testing.T) {
 	defer CloseAllServers(servers)
 
 	var errg errgroup.Group
-	for i := 0; i < 10; i++ {
+	for range 3 {
 		errg.Go(testTCPConn(clientPort, 10240*1024, time.Second*20))
 	}
 	if err := errg.Wait(); err != nil {
diff --git a/testing/scenarios/reverse_test.go b/testing/scenarios/reverse_test.go
index faaa402e..f7e2e7af 100644
--- a/testing/scenarios/reverse_test.go
+++ b/testing/scenarios/reverse_test.go
@@ -182,7 +182,7 @@ func TestReverseProxy(t *testing.T) {
 	defer CloseAllServers(servers)
 
 	var errg errgroup.Group
-	for i := 0; i < 32; i++ {
+	for range 32 {
 		errg.Go(testTCPConn(externalPort, 10240*1024, time.Second*40))
 	}
 
@@ -374,7 +374,7 @@ func TestReverseProxyLongRunning(t *testing.T) {
 
 	defer CloseAllServers(servers)
 
-	for i := 0; i < 4096; i++ {
+	for range 4096 {
 		if err := testTCPConn(externalPort, 1024, time.Second*20)(); err != nil {
 			t.Error(err)
 		}
diff --git a/testing/scenarios/shadowsocks_2022_test.go b/testing/scenarios/shadowsocks_2022_test.go
index f06c38dc..7282eff3 100644
--- a/testing/scenarios/shadowsocks_2022_test.go
+++ b/testing/scenarios/shadowsocks_2022_test.go
@@ -124,7 +124,7 @@ func testShadowsocks2022Tcp(t *testing.T, method string, password string) {
 	defer CloseAllServers(servers)
 
 	var errGroup errgroup.Group
-	for i := 0; i < 10; i++ {
+	for range 3 {
 		errGroup.Go(testTCPConn(clientPort, 10240*1024, time.Second*20))
 	}
 
@@ -207,7 +207,7 @@ func testShadowsocks2022Udp(t *testing.T, method string, password string) {
 	defer CloseAllServers(servers)
 
 	var errGroup errgroup.Group
-	for i := 0; i < 2; i++ {
+	for range 3 {
 		errGroup.Go(testUDPConn(udpClientPort, 1024, time.Second*5))
 	}
 
diff --git a/testing/scenarios/shadowsocks_test.go b/testing/scenarios/shadowsocks_test.go
index e7620429..f358cbe2 100644
--- a/testing/scenarios/shadowsocks_test.go
+++ b/testing/scenarios/shadowsocks_test.go
@@ -96,7 +96,7 @@ func TestShadowsocksChaCha20Poly1305TCP(t *testing.T) {
 	defer CloseAllServers(servers)
 
 	var errGroup errgroup.Group
-	for i := 0; i < 10; i++ {
+	for range 3 {
 		errGroup.Go(testTCPConn(clientPort, 10240*1024, time.Second*20))
 	}
 	if err := errGroup.Wait(); err != nil {
@@ -192,7 +192,7 @@ func TestShadowsocksAES256GCMTCP(t *testing.T) {
 	defer CloseAllServers(servers)
 
 	var errGroup errgroup.Group
-	for i := 0; i < 10; i++ {
+	for range 3 {
 		errGroup.Go(testTCPConn(clientPort, 10240*1024, time.Second*20))
 	}
 
@@ -289,7 +289,7 @@ func TestShadowsocksAES128GCMUDP(t *testing.T) {
 	defer CloseAllServers(servers)
 
 	var errGroup errgroup.Group
-	for i := 0; i < 2; i++ {
+	for range 3 {
 		errGroup.Go(testUDPConn(clientPort, 1024, time.Second*5))
 	}
 	if err := errGroup.Wait(); err != nil {
@@ -391,7 +391,7 @@ func TestShadowsocksAES128GCMUDPMux(t *testing.T) {
 	defer CloseAllServers(servers)
 
 	var errGroup errgroup.Group
-	for i := 0; i < 2; i++ {
+	for range 3 {
 		errGroup.Go(testUDPConn(clientPort, 1024, time.Second*5))
 	}
 	if err := errGroup.Wait(); err != nil {
@@ -477,7 +477,7 @@ func TestShadowsocksNone(t *testing.T) {
 	defer CloseAllServers(servers)
 
 	var errGroup errgroup.Group
-	for i := 0; i < 10; i++ {
+	for range 3 {
 		errGroup.Go(testTCPConn(clientPort, 10240*1024, time.Second*20))
 	}
 
diff --git a/testing/scenarios/tls_test.go b/testing/scenarios/tls_test.go
index a8abccd7..bf0d2c8a 100644
--- a/testing/scenarios/tls_test.go
+++ b/testing/scenarios/tls_test.go
@@ -240,7 +240,7 @@ func TestAutoIssuingCertificate(t *testing.T) {
 	common.Must(err)
 	defer CloseAllServers(servers)
 
-	for i := 0; i < 10; i++ {
+	for range 3 {
 		if err := testTCPConn(clientPort, 1024, time.Second*20)(); err != nil {
 			t.Error(err)
 		}
@@ -449,7 +449,7 @@ func TestTLSOverWebSocket(t *testing.T) {
 	defer CloseAllServers(servers)
 
 	var errg errgroup.Group
-	for i := 0; i < 10; i++ {
+	for range 3 {
 		errg.Go(testTCPConn(clientPort, 10240*1024, time.Second*20))
 	}
 	if err := errg.Wait(); err != nil {
@@ -565,7 +565,7 @@ func TestGRPC(t *testing.T) {
 	defer CloseAllServers(servers)
 
 	var errg errgroup.Group
-	for i := 0; i < 10; i++ {
+	for range 3 {
 		errg.Go(testTCPConn(clientPort, 1024*10240, time.Second*40))
 	}
 	if err := errg.Wait(); err != nil {
@@ -681,7 +681,7 @@ func TestGRPCMultiMode(t *testing.T) {
 	defer CloseAllServers(servers)
 
 	var errg errgroup.Group
-	for i := 0; i < 10; i++ {
+	for range 3 {
 		errg.Go(testTCPConn(clientPort, 1024*10240, time.Second*40))
 	}
 	if err := errg.Wait(); err != nil {
diff --git a/testing/scenarios/vless_test.go b/testing/scenarios/vless_test.go
index dcac17ea..52a6712f 100644
--- a/testing/scenarios/vless_test.go
+++ b/testing/scenarios/vless_test.go
@@ -117,7 +117,7 @@ func TestVless(t *testing.T) {
 	defer CloseAllServers(servers)
 
 	var errg errgroup.Group
-	for i := 0; i < 10; i++ {
+	for range 3 {
 		errg.Go(testTCPConn(clientPort, 1024*1024, time.Second*30))
 	}
 	if err := errg.Wait(); err != nil {
@@ -239,7 +239,7 @@ func TestVlessTls(t *testing.T) {
 	defer CloseAllServers(servers)
 
 	var errg errgroup.Group
-	for i := 0; i < 10; i++ {
+	for range 3 {
 		errg.Go(testTCPConn(clientPort, 1024*1024, time.Second*30))
 	}
 	if err := errg.Wait(); err != nil {
@@ -363,7 +363,7 @@ func TestVlessXtlsVision(t *testing.T) {
 	defer CloseAllServers(servers)
 
 	var errg errgroup.Group
-	for i := 0; i < 10; i++ {
+	for range 3 {
 		errg.Go(testTCPConn(clientPort, 1024*1024, time.Second*30))
 	}
 	if err := errg.Wait(); err != nil {
@@ -502,7 +502,7 @@ func TestVlessXtlsVisionReality(t *testing.T) {
 	defer CloseAllServers(servers)
 
 	var errg errgroup.Group
-	for i := 0; i < 1; i++ {
+	for range 3 {
 		errg.Go(testTCPConn(clientPort, 1024*1024, time.Second*30))
 	}
 	if err := errg.Wait(); err != nil {
diff --git a/testing/scenarios/vmess_test.go b/testing/scenarios/vmess_test.go
index dbffe0d6..012fc96c 100644
--- a/testing/scenarios/vmess_test.go
+++ b/testing/scenarios/vmess_test.go
@@ -260,7 +260,7 @@ func TestVMessGCM(t *testing.T) {
 	defer CloseAllServers(servers)
 
 	var errg errgroup.Group
-	for i := 0; i < 10; i++ {
+	for range 3 {
 		errg.Go(testTCPConn(clientPort, 10240*1024, time.Second*40))
 	}
 
@@ -366,7 +366,7 @@ func TestVMessGCMReadv(t *testing.T) {
 	defer CloseAllServers(servers)
 
 	var errg errgroup.Group
-	for i := 0; i < 10; i++ {
+	for range 3 {
 		errg.Go(testTCPConn(clientPort, 10240*1024, time.Second*40))
 	}
 	if err := errg.Wait(); err != nil {
@@ -465,7 +465,7 @@ func TestVMessGCMUDP(t *testing.T) {
 	defer CloseAllServers(servers)
 
 	var errg errgroup.Group
-	for i := 0; i < 2; i++ {
+	for range 3 {
 		errg.Go(testUDPConn(clientPort, 1024, time.Second*5))
 	}
 	if err := errg.Wait(); err != nil {
@@ -564,7 +564,7 @@ func TestVMessChacha20(t *testing.T) {
 	defer CloseAllServers(servers)
 
 	var errg errgroup.Group
-	for i := 0; i < 10; i++ {
+	for range 3 {
 		errg.Go(testTCPConn(clientPort, 10240*1024, time.Second*20))
 	}
 
@@ -664,7 +664,7 @@ func TestVMessNone(t *testing.T) {
 	defer CloseAllServers(servers)
 
 	var errg errgroup.Group
-	for i := 0; i < 10; i++ {
+	for range 3 {
 		errg.Go(testTCPConn(clientPort, 1024*1024, time.Second*30))
 	}
 	if err := errg.Wait(); err != nil {
@@ -771,7 +771,7 @@ func TestVMessKCP(t *testing.T) {
 	defer CloseAllServers(servers)
 
 	var errg errgroup.Group
-	for i := 0; i < 2; i++ {
+	for range 3 {
 		errg.Go(testTCPConn(clientPort, 1024, time.Minute*2))
 	}
 	if err := errg.Wait(); err != nil {
@@ -915,7 +915,7 @@ func TestVMessKCPLarge(t *testing.T) {
 	common.Must(err)
 
 	var errg errgroup.Group
-	for i := 0; i < 2; i++ {
+	for range 3 {
 		errg.Go(testTCPConn(clientPort, 513*1024, time.Minute*5))
 	}
 	if err := errg.Wait(); err != nil {
@@ -1026,7 +1026,7 @@ func TestVMessGCMMux(t *testing.T) {
 
 	for range "abcd" {
 		var errg errgroup.Group
-		for i := 0; i < 16; i++ {
+		for range 3 {
 			errg.Go(testTCPConn(clientPort, 10240, time.Second*20))
 		}
 		if err := errg.Wait(); err != nil {
@@ -1152,7 +1152,7 @@ func TestVMessGCMMuxUDP(t *testing.T) {
 
 	for range "ab" {
 		var errg errgroup.Group
-		for i := 0; i < 2; i++ {
+		for range 3 {
 			errg.Go(testTCPConn(clientPort, 1024, time.Second*10))
 			errg.Go(testUDPConn(clientUDPPort, 1024, time.Second*10))
 		}
@@ -1259,7 +1259,7 @@ func TestVMessZero(t *testing.T) {
 	defer CloseAllServers(servers)
 
 	var errg errgroup.Group
-	for i := 0; i < 10; i++ {
+	for range 3 {
 		errg.Go(testTCPConn(clientPort, 1024*1024, time.Second*30))
 	}
 	if err := errg.Wait(); err != nil {
@@ -1361,7 +1361,7 @@ func TestVMessGCMLengthAuth(t *testing.T) {
 	defer CloseAllServers(servers)
 
 	var errg errgroup.Group
-	for i := 0; i < 10; i++ {
+	for range 3 {
 		errg.Go(testTCPConn(clientPort, 10240*1024, time.Second*40))
 	}
 
@@ -1465,7 +1465,7 @@ func TestVMessGCMLengthAuthPlusNoTerminationSignal(t *testing.T) {
 	defer CloseAllServers(servers)
 
 	var errg errgroup.Group
-	for i := 0; i < 10; i++ {
+	for range 3 {
 		errg.Go(testTCPConn(clientPort, 10240*1024, time.Second*40))
 	}