diff --git a/app/router/rules/router_test.go b/app/router/rules/router_test.go
index b01cfb75e..2babded38 100644
--- a/app/router/rules/router_test.go
+++ b/app/router/rules/router_test.go
@@ -26,5 +26,5 @@ func TestSimpleRouter(t *testing.T) {
 
 	tag, err := router.TakeDetour(v2net.NewTCPDestination(v2net.DomainAddress("v2ray.com", 80)))
 	assert.Error(err).IsNil()
-	assert.String(tag).Equals("test")
+	assert.StringLiteral(tag).Equals("test")
 }
diff --git a/common/net/testing/unit/address_test.go b/common/net/testing/unit/address_test.go
index 8701debd5..7a7f566a0 100644
--- a/common/net/testing/unit/address_test.go
+++ b/common/net/testing/unit/address_test.go
@@ -22,7 +22,7 @@ func TestIPv4Address(t *testing.T) {
 	v2netassert.Address(addr).IsNotDomain()
 	assert.Bytes(addr.IP()).Equals(ip)
 	v2netassert.Port(addr.Port()).Equals(port)
-	assert.String(addr.String()).Equals("1.2.3.4:80")
+	assert.String(addr).Equals("1.2.3.4:80")
 }
 
 func TestIPv6Address(t *testing.T) {
@@ -42,7 +42,7 @@ func TestIPv6Address(t *testing.T) {
 	v2netassert.Address(addr).IsNotDomain()
 	assert.Bytes(addr.IP()).Equals(ip)
 	assert.Uint16(addr.Port().Value()).Equals(port.Value())
-	assert.String(addr.String()).Equals("[102:304:102:304:102:304:102:304]:443")
+	assert.String(addr).Equals("[102:304:102:304:102:304:102:304]:443")
 }
 
 func TestDomainAddress(t *testing.T) {
@@ -55,9 +55,9 @@ func TestDomainAddress(t *testing.T) {
 	v2netassert.Address(addr).IsDomain()
 	v2netassert.Address(addr).IsNotIPv6()
 	v2netassert.Address(addr).IsNotIPv4()
-	assert.String(addr.Domain()).Equals(domain)
+	assert.StringLiteral(addr.Domain()).Equals(domain)
 	assert.Uint16(addr.Port().Value()).Equals(port.Value())
-	assert.String(addr.String()).Equals("v2ray.com:443")
+	assert.String(addr).Equals("v2ray.com:443")
 }
 
 func TestNetIPv4Address(t *testing.T) {
@@ -67,5 +67,5 @@ func TestNetIPv4Address(t *testing.T) {
 	port := v2net.NewPort(80)
 	addr := v2net.IPAddress(ip, port.Value())
 	v2netassert.Address(addr).IsIPv4()
-	assert.String(addr.String()).Equals("1.2.3.4:80")
+	assert.String(addr).Equals("1.2.3.4:80")
 }
diff --git a/common/net/testing/unit/destination_test.go b/common/net/testing/unit/destination_test.go
index 39c53de85..cac581118 100644
--- a/common/net/testing/unit/destination_test.go
+++ b/common/net/testing/unit/destination_test.go
@@ -14,7 +14,7 @@ func TestTCPDestination(t *testing.T) {
 	dest := v2net.NewTCPDestination(v2net.IPAddress([]byte{1, 2, 3, 4}, 80))
 	assert.Bool(dest.IsTCP()).IsTrue()
 	assert.Bool(dest.IsUDP()).IsFalse()
-	assert.String(dest.String()).Equals("tcp:1.2.3.4:80")
+	assert.StringLiteral(dest.String()).Equals("tcp:1.2.3.4:80")
 }
 
 func TestUDPDestination(t *testing.T) {
@@ -23,5 +23,5 @@ func TestUDPDestination(t *testing.T) {
 	dest := v2net.NewUDPDestination(v2net.IPAddress([]byte{0x20, 0x01, 0x48, 0x60, 0x48, 0x60, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x88, 0x88}, 53))
 	assert.Bool(dest.IsTCP()).IsFalse()
 	assert.Bool(dest.IsUDP()).IsTrue()
-	assert.String(dest.String()).Equals("udp:[2001:4860:4860::8888]:53")
+	assert.StringLiteral(dest.String()).Equals("udp:[2001:4860:4860::8888]:53")
 }
diff --git a/proxy/dokodemo/dokodemo_test.go b/proxy/dokodemo/dokodemo_test.go
index e5ea38013..ab1a60ddd 100644
--- a/proxy/dokodemo/dokodemo_test.go
+++ b/proxy/dokodemo/dokodemo_test.go
@@ -75,7 +75,7 @@ func TestDokodemoTCP(t *testing.T) {
 	assert.Error(err).IsNil()
 	tcpClient.Close()
 
-	assert.String("Processed: " + data2Send).Equals(string(response[:nBytes]))
+	assert.StringLiteral("Processed: " + data2Send).Equals(string(response[:nBytes]))
 }
 
 func TestDokodemoUDP(t *testing.T) {
@@ -136,5 +136,5 @@ func TestDokodemoUDP(t *testing.T) {
 	assert.Error(err).IsNil()
 	udpClient.Close()
 
-	assert.String("Processed: " + data2Send).Equals(string(response[:nBytes]))
+	assert.StringLiteral("Processed: " + data2Send).Equals(string(response[:nBytes]))
 }
diff --git a/proxy/socks/config/json/config_test.go b/proxy/socks/config/json/config_test.go
index 75be4d60b..2967ed329 100644
--- a/proxy/socks/config/json/config_test.go
+++ b/proxy/socks/config/json/config_test.go
@@ -28,7 +28,7 @@ func TestDefaultIPAddress(t *testing.T) {
 	v2testing.Current(t)
 
 	socksConfig := jsonconfig.CreateConfig("socks", config.TypeInbound).(*SocksConfig)
-	assert.String(socksConfig.IP().String()).Equals("127.0.0.1")
+	assert.StringLiteral(socksConfig.IP().String()).Equals("127.0.0.1")
 }
 
 func TestIPAddressParsing(t *testing.T) {
@@ -37,7 +37,7 @@ func TestIPAddressParsing(t *testing.T) {
 	var ipAddress IPAddress
 	err := json.Unmarshal([]byte("\"1.2.3.4\""), &ipAddress)
 	assert.Error(err).IsNil()
-	assert.String(net.IP(ipAddress).String()).Equals("1.2.3.4")
+	assert.StringLiteral(net.IP(ipAddress).String()).Equals("1.2.3.4")
 }
 
 func TestNoAuthConfig(t *testing.T) {
@@ -48,7 +48,7 @@ func TestNoAuthConfig(t *testing.T) {
 	assert.Error(err).IsNil()
 	assert.Bool(config.IsNoAuth()).IsTrue()
 	assert.Bool(config.IsPassword()).IsFalse()
-	assert.String(config.IP().String()).Equals("8.8.8.8")
+	assert.StringLiteral(config.IP().String()).Equals("8.8.8.8")
 	assert.Bool(config.UDPEnabled).IsFalse()
 }
 
diff --git a/proxy/socks/protocol/udp_test.go b/proxy/socks/protocol/udp_test.go
index cda330577..774c2167e 100644
--- a/proxy/socks/protocol/udp_test.go
+++ b/proxy/socks/protocol/udp_test.go
@@ -31,6 +31,6 @@ func TestDomainAddressRequest(t *testing.T) {
 	assert.Error(err).IsNil()
 
 	assert.Byte(request.Fragment).Equals(1)
-	assert.String(request.Address.String()).Equals("v2ray.com:80")
+	assert.StringLiteral(request.Address.String()).Equals("v2ray.com:80")
 	assert.Bytes(request.Data.Value).Equals([]byte("Actual payload"))
 }
diff --git a/proxy/socks/socks_test.go b/proxy/socks/socks_test.go
index 4d1934c57..ec728f568 100644
--- a/proxy/socks/socks_test.go
+++ b/proxy/socks/socks_test.go
@@ -71,7 +71,7 @@ func TestSocksTcpConnect(t *testing.T) {
 
 	assert.Bytes([]byte(data2Send)).Equals(connOutput.Bytes())
 	assert.Bytes(dataReturned).Equals(connInput)
-	assert.String(targetServer).Equals(och.Destination.Address().String())
+	assert.StringLiteral(targetServer).Equals(och.Destination.Address().String())
 }
 
 func TestSocksTcpConnectWithUserPass(t *testing.T) {
@@ -129,7 +129,7 @@ func TestSocksTcpConnectWithUserPass(t *testing.T) {
 
 	assert.Bytes([]byte(data2Send)).Equals(connOutput.Bytes())
 	assert.Bytes(dataReturned).Equals(connInput)
-	assert.String(targetServer).Equals(och.Destination.Address().String())
+	assert.StringLiteral(targetServer).Equals(och.Destination.Address().String())
 }
 
 func TestSocksTcpConnectWithWrongUserPass(t *testing.T) {
@@ -277,5 +277,5 @@ func TestSocksUdpSend(t *testing.T) {
 	assert.Error(err).IsNil()
 	assert.Bytes(response[10:nBytes]).Equals(connInput)
 	assert.Bytes(data2Send).Equals(connOutput.Bytes())
-	assert.String(och.Destination.String()).Equals("udp:8.8.4.4:53")
+	assert.StringLiteral(och.Destination.String()).Equals("udp:8.8.4.4:53")
 }
diff --git a/proxy/vmess/protocol/vmess_test.go b/proxy/vmess/protocol/vmess_test.go
index 4d714c2d4..9651d46cf 100644
--- a/proxy/vmess/protocol/vmess_test.go
+++ b/proxy/vmess/protocol/vmess_test.go
@@ -73,12 +73,12 @@ func TestVMessSerialization(t *testing.T) {
 	}
 
 	assert.Byte(actualRequest.Version).Named("Version").Equals(byte(0x01))
-	assert.String(actualRequest.User.ID().String).Named("UserId").Equals(request.User.ID().String)
+	assert.StringLiteral(actualRequest.User.ID().String).Named("UserId").Equals(request.User.ID().String)
 	assert.Bytes(actualRequest.RequestIV).Named("RequestIV").Equals(request.RequestIV[:])
 	assert.Bytes(actualRequest.RequestKey).Named("RequestKey").Equals(request.RequestKey[:])
 	assert.Bytes(actualRequest.ResponseHeader).Named("ResponseHeader").Equals(request.ResponseHeader[:])
 	assert.Byte(actualRequest.Command).Named("Command").Equals(request.Command)
-	assert.String(actualRequest.Address.String()).Named("Address").Equals(request.Address.String())
+	assert.StringLiteral(actualRequest.Address.String()).Named("Address").Equals(request.Address.String())
 }
 
 func TestReadSingleByte(t *testing.T) {
diff --git a/shell/point/config/json/json_test.go b/shell/point/config/json/json_test.go
index 135eeec2a..331a9073e 100644
--- a/shell/point/config/json/json_test.go
+++ b/shell/point/config/json/json_test.go
@@ -27,10 +27,10 @@ func TestClientSampleConfig(t *testing.T) {
 	assert.Pointer(pointConfig.InboundConfig()).IsNotNil()
 	assert.Pointer(pointConfig.OutboundConfig()).IsNotNil()
 
-	assert.String(pointConfig.InboundConfig().Protocol()).Equals("socks")
+	assert.StringLiteral(pointConfig.InboundConfig().Protocol()).Equals("socks")
 	assert.Pointer(pointConfig.InboundConfig().Settings()).IsNotNil()
 
-	assert.String(pointConfig.OutboundConfig().Protocol()).Equals("vmess")
+	assert.StringLiteral(pointConfig.OutboundConfig().Protocol()).Equals("vmess")
 	assert.Pointer(pointConfig.OutboundConfig().Settings()).IsNotNil()
 }
 
@@ -47,10 +47,10 @@ func TestServerSampleConfig(t *testing.T) {
 	assert.Pointer(pointConfig.InboundConfig()).IsNotNil()
 	assert.Pointer(pointConfig.OutboundConfig()).IsNotNil()
 
-	assert.String(pointConfig.InboundConfig().Protocol()).Equals("vmess")
+	assert.StringLiteral(pointConfig.InboundConfig().Protocol()).Equals("vmess")
 	assert.Pointer(pointConfig.InboundConfig().Settings()).IsNotNil()
 
-	assert.String(pointConfig.OutboundConfig().Protocol()).Equals("freedom")
+	assert.StringLiteral(pointConfig.OutboundConfig().Protocol()).Equals("freedom")
 	assert.Pointer(pointConfig.OutboundConfig().Settings()).IsNotNil()
 }
 
@@ -67,7 +67,7 @@ func TestDetourConfig(t *testing.T) {
 	assert.Int(len(detours)).Equals(1)
 
 	detour := detours[0]
-	assert.String(detour.Protocol()).Equals("dokodemo-door")
+	assert.StringLiteral(detour.Protocol()).Equals("dokodemo-door")
 	assert.Uint16(detour.PortRange().From().Value()).Equals(uint16(28394))
 	assert.Uint16(detour.PortRange().To().Value()).Equals(uint16(28394))
 	assert.Pointer(detour.Settings()).IsNotNil()
diff --git a/testing/assert/stringsubject.go b/testing/assert/stringsubject.go
index 1a9b8e822..09d026736 100644
--- a/testing/assert/stringsubject.go
+++ b/testing/assert/stringsubject.go
@@ -1,12 +1,20 @@
 package assert
 
-func String(value string) *StringSubject {
+import (
+  "github.com/v2ray/v2ray-core/common/serial"
+)
+
+func StringLiteral(value string) *StringSubject {
+  return String(serial.StringLiteral((value)))
+}
+
+func String(value serial.String) *StringSubject {
 	return &StringSubject{value: value}
 }
 
 type StringSubject struct {
 	Subject
-	value string
+	value serial.String
 }
 
 func (subject *StringSubject) Named(name string) *StringSubject {
@@ -14,16 +22,12 @@ func (subject *StringSubject) Named(name string) *StringSubject {
 	return subject
 }
 
-func (subject *StringSubject) Fail(verb string, other string) {
-	subject.FailWithMessage("Not true that " + subject.DisplayString() + " " + verb + " <" + other + ">.")
-}
-
 func (subject *StringSubject) DisplayString() string {
-	return subject.Subject.DisplayString(subject.value)
+	return subject.Subject.DisplayString(subject.value.String())
 }
 
 func (subject *StringSubject) Equals(expectation string) {
-	if subject.value != expectation {
-		subject.Fail("is equal to", expectation)
+	if subject.value.String() != expectation {
+		subject.Fail(subject.DisplayString(), "is equal to", serial.StringLiteral(expectation))
 	}
 }
diff --git a/testing/scenarios/socks_end_test.go b/testing/scenarios/socks_end_test.go
index de1bf82fc..5d03796e2 100644
--- a/testing/scenarios/socks_end_test.go
+++ b/testing/scenarios/socks_end_test.go
@@ -72,7 +72,7 @@ func TestTCPConnection(t *testing.T) {
 		actualResponse := make([]byte, 1024)
 		nBytes, err = conn.Read(actualResponse)
 		assert.Error(err).IsNil()
-		assert.String(string(actualResponse[:nBytes])).Equals("Processed: Request to target server.Request to target server again.")
+		assert.StringLiteral(string(actualResponse[:nBytes])).Equals("Processed: Request to target server.Request to target server again.")
 
 		conn.Close()
 	}