diff --git a/common/protocol/http/headers_test.go b/common/protocol/http/headers_test.go
index e4121569..5716d075 100644
--- a/common/protocol/http/headers_test.go
+++ b/common/protocol/http/headers_test.go
@@ -6,26 +6,23 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/google/go-cmp/cmp"
+
 	"v2ray.com/core/common"
 	"v2ray.com/core/common/net"
 	. "v2ray.com/core/common/protocol/http"
-	. "v2ray.com/ext/assert"
 )
 
 func TestParseXForwardedFor(t *testing.T) {
-	assert := With(t)
-
 	header := http.Header{}
 	header.Add("X-Forwarded-For", "129.78.138.66, 129.78.64.103")
 	addrs := ParseXForwardedFor(header)
-	assert(len(addrs), Equals, 2)
-	assert(addrs[0].String(), Equals, "129.78.138.66")
-	assert(addrs[1].String(), Equals, "129.78.64.103")
+	if r := cmp.Diff(addrs, []net.Address{net.ParseAddress("129.78.138.66"), net.ParseAddress("129.78.64.103")}); r != "" {
+		t.Error(r)
+	}
 }
 
 func TestHopByHopHeadersRemoving(t *testing.T) {
-	assert := With(t)
-
 	rawRequest := `GET /pkg/net/http/ HTTP/1.1
 Host: golang.org
 Connection: keep-alive,Foo, Bar
@@ -42,18 +39,44 @@ Accept-Language: de,en;q=0.7,en-us;q=0.3
 	b := bufio.NewReader(strings.NewReader(rawRequest))
 	req, err := http.ReadRequest(b)
 	common.Must(err)
-	assert(req.Header.Get("Foo"), Equals, "foo")
-	assert(req.Header.Get("Bar"), Equals, "bar")
-	assert(req.Header.Get("Connection"), Equals, "keep-alive,Foo, Bar")
-	assert(req.Header.Get("Proxy-Connection"), Equals, "keep-alive")
-	assert(req.Header.Get("Proxy-Authenticate"), Equals, "abc")
+	headers := []struct {
+		Key   string
+		Value string
+	}{
+		{
+			Key:   "Foo",
+			Value: "foo",
+		},
+		{
+			Key:   "Bar",
+			Value: "bar",
+		},
+		{
+			Key:   "Connection",
+			Value: "keep-alive,Foo, Bar",
+		},
+		{
+			Key:   "Proxy-Connection",
+			Value: "keep-alive",
+		},
+		{
+			Key:   "Proxy-Authenticate",
+			Value: "abc",
+		},
+	}
+	for _, header := range headers {
+		if v := req.Header.Get(header.Key); v != header.Value {
+			t.Error("header ", header.Key, " = ", v, " want ", header.Value)
+		}
+	}
 
 	RemoveHopByHopHeaders(req.Header)
-	assert(req.Header.Get("Connection"), IsEmpty)
-	assert(req.Header.Get("Foo"), IsEmpty)
-	assert(req.Header.Get("Bar"), IsEmpty)
-	assert(req.Header.Get("Proxy-Connection"), IsEmpty)
-	assert(req.Header.Get("Proxy-Authenticate"), IsEmpty)
+
+	for _, header := range []string{"Connection", "Foo", "Bar", "Proxy-Connection", "Proxy-Authenticate"} {
+		if v := req.Header.Get(header); v != "" {
+			t.Error("header ", header, " = ", v)
+		}
+	}
 }
 
 func TestParseHost(t *testing.T) {
diff --git a/testing/scenarios/command_test.go b/testing/scenarios/command_test.go
index deb6be51..156f4d0b 100644
--- a/testing/scenarios/command_test.go
+++ b/testing/scenarios/command_test.go
@@ -3,7 +3,6 @@ package scenarios
 import (
 	"context"
 	"fmt"
-	"io"
 	"testing"
 	"time"
 
@@ -29,12 +28,9 @@ import (
 	"v2ray.com/core/proxy/vmess/inbound"
 	"v2ray.com/core/proxy/vmess/outbound"
 	"v2ray.com/core/testing/servers/tcp"
-	. "v2ray.com/ext/assert"
 )
 
 func TestCommanderRemoveHandler(t *testing.T) {
-	assert := With(t)
-
 	tcpServer := tcp.Server{
 		MsgProcessor: xor,
 	}
@@ -99,30 +95,10 @@ func TestCommanderRemoveHandler(t *testing.T) {
 
 	servers, err := InitializeServerConfigs(clientConfig)
 	common.Must(err)
-
 	defer CloseAllServers(servers)
 
-	{
-		conn, err := net.DialTCP("tcp", nil, &net.TCPAddr{
-			IP:   []byte{127, 0, 0, 1},
-			Port: int(clientPort),
-		})
-		if err != nil {
-			t.Fatal(err)
-		}
-		defer conn.Close() // nolint: errcheck
-
-		payload := "commander request."
-		nBytes, err := conn.Write([]byte(payload))
-		common.Must(err)
-		assert(nBytes, Equals, len(payload))
-
-		response := make([]byte, 1024)
-		nBytes, err = conn.Read(response)
-		common.Must(err)
-		if r := cmp.Diff(response[:nBytes], xor([]byte(payload))); r != "" {
-			t.Fatal(r)
-		}
+	if err := testTCPConn(clientPort, 1024, time.Second*5)(); err != nil {
+		t.Fatal(err)
 	}
 
 	cmdConn, err := grpc.Dial(fmt.Sprintf("127.0.0.1:%d", cmdPort), grpc.WithInsecure(), grpc.WithBlock())
@@ -134,20 +110,22 @@ func TestCommanderRemoveHandler(t *testing.T) {
 		Tag: "d",
 	})
 	common.Must(err)
-	assert(resp, IsNotNil)
+	if resp == nil {
+		t.Error("unexpected nil response")
+	}
 
 	{
 		_, err := net.DialTCP("tcp", nil, &net.TCPAddr{
 			IP:   []byte{127, 0, 0, 1},
 			Port: int(clientPort),
 		})
-		assert(err, IsNotNil)
+		if err == nil {
+			t.Error("unexpected nil error")
+		}
 	}
 }
 
 func TestCommanderAddRemoveUser(t *testing.T) {
-	assert := With(t)
-
 	tcpServer := tcp.Server{
 		MsgProcessor: xor,
 	}
@@ -284,24 +262,10 @@ func TestCommanderAddRemoveUser(t *testing.T) {
 
 	servers, err := InitializeServerConfigs(serverConfig, clientConfig)
 	common.Must(err)
+	CloseAllServers(servers)
 
-	{
-		conn, err := net.DialTCP("tcp", nil, &net.TCPAddr{
-			IP:   []byte{127, 0, 0, 1},
-			Port: int(clientPort),
-		})
-		common.Must(err)
-
-		payload := "commander request."
-		nBytes, err := conn.Write([]byte(payload))
-		common.Must(err)
-		assert(nBytes, Equals, len(payload))
-
-		response := make([]byte, 1024)
-		nBytes, err = conn.Read(response)
-		assert(nBytes, Equals, 0)
-		assert(err, Equals, io.EOF)
-		assert(conn.Close(), IsNil)
+	if err := testTCPConn(clientPort, 1024, time.Second*5)(); err != nil {
+		t.Fatal(err)
 	}
 
 	cmdConn, err := grpc.Dial(fmt.Sprintf("127.0.0.1:%d", cmdPort), grpc.WithInsecure(), grpc.WithBlock())
@@ -323,40 +287,25 @@ func TestCommanderAddRemoveUser(t *testing.T) {
 			}),
 	})
 	common.Must(err)
-	assert(resp, IsNotNil)
+	if resp == nil {
+		t.Fatal("nil response")
+	}
 
-	{
-		conn, err := net.DialTCP("tcp", nil, &net.TCPAddr{
-			IP:   []byte{127, 0, 0, 1},
-			Port: int(clientPort),
-		})
-		common.Must(err)
-
-		payload := "commander request."
-		nBytes, err := conn.Write([]byte(payload))
-		common.Must(err)
-		assert(nBytes, Equals, len(payload))
-
-		response := make([]byte, 1024)
-		nBytes, err = conn.Read(response)
-		common.Must(err)
-		assert(response[:nBytes], Equals, xor([]byte(payload)))
-		assert(conn.Close(), IsNil)
+	if err := testTCPConn(clientPort, 1024, time.Second*5)(); err != nil {
+		t.Fatal(err)
 	}
 
 	resp, err = hsClient.AlterInbound(context.Background(), &command.AlterInboundRequest{
 		Tag:       "v",
 		Operation: serial.ToTypedMessage(&command.RemoveUserOperation{Email: "test@v2ray.com"}),
 	})
-	assert(resp, IsNotNil)
 	common.Must(err)
-
-	CloseAllServers(servers)
+	if resp == nil {
+		t.Fatal("nil response")
+	}
 }
 
 func TestCommanderStats(t *testing.T) {
-	assert := With(t)
-
 	tcpServer := tcp.Server{
 		MsgProcessor: xor,
 	}
@@ -515,20 +464,30 @@ func TestCommanderStats(t *testing.T) {
 		Reset_: true,
 	})
 	common.Must(err)
-	assert(sresp.Stat.Name, Equals, name)
-	assert(sresp.Stat.Value, Equals, int64(10240*1024))
+	if r := cmp.Diff(sresp.Stat, &statscmd.Stat{
+		Name:  name,
+		Value: 10240 * 1024,
+	}); r != "" {
+		t.Error(r)
+	}
 
 	sresp, err = sClient.GetStats(context.Background(), &statscmd.GetStatsRequest{
 		Name: name,
 	})
 	common.Must(err)
-	assert(sresp.Stat.Name, Equals, name)
-	assert(sresp.Stat.Value, Equals, int64(0))
+	if r := cmp.Diff(sresp.Stat, &statscmd.Stat{
+		Name:  name,
+		Value: 0,
+	}); r != "" {
+		t.Error(r)
+	}
 
 	sresp, err = sClient.GetStats(context.Background(), &statscmd.GetStatsRequest{
 		Name:   "inbound>>>vmess>>>traffic>>>uplink",
 		Reset_: true,
 	})
 	common.Must(err)
-	assert(sresp.Stat.Value, GreaterThan, int64(10240*1024))
+	if sresp.Stat.Value <= 10240*1024 {
+		t.Error("value < 10240*1024: ", sresp.Stat.Value)
+	}
 }
diff --git a/testing/scenarios/common.go b/testing/scenarios/common.go
index ab90634a..7a726783 100644
--- a/testing/scenarios/common.go
+++ b/testing/scenarios/common.go
@@ -160,6 +160,27 @@ func testTCPConn(port net.Port, payloadSize int, timeout time.Duration) func() e
 		}
 		defer conn.Close()
 
+		return testTCPConn2(conn, payloadSize, timeout)()
+	}
+}
+
+func testUDPConn(port net.Port, payloadSize int, timeout time.Duration) func() error {
+	return func() error {
+		conn, err := net.DialUDP("udp", nil, &net.UDPAddr{
+			IP:   []byte{127, 0, 0, 1},
+			Port: int(port),
+		})
+		if err != nil {
+			return err
+		}
+		defer conn.Close()
+
+		return testTCPConn2(conn, payloadSize, timeout)()
+	}
+}
+
+func testTCPConn2(conn net.Conn, payloadSize int, timeout time.Duration) func() error {
+	return func() error {
 		payload := make([]byte, payloadSize)
 		common.Must2(rand.Read(payload))
 
diff --git a/testing/scenarios/dns_test.go b/testing/scenarios/dns_test.go
index 0451dd4a..e0ccb554 100644
--- a/testing/scenarios/dns_test.go
+++ b/testing/scenarios/dns_test.go
@@ -3,6 +3,7 @@ package scenarios
 import (
 	"fmt"
 	"testing"
+	"time"
 
 	xproxy "golang.org/x/net/proxy"
 	"v2ray.com/core"
@@ -16,12 +17,9 @@ import (
 	"v2ray.com/core/proxy/freedom"
 	"v2ray.com/core/proxy/socks"
 	"v2ray.com/core/testing/servers/tcp"
-	. "v2ray.com/ext/assert"
 )
 
 func TestResolveIP(t *testing.T) {
-	assert := With(t)
-
 	tcpServer := tcp.Server{
 		MsgProcessor: xor,
 	}
@@ -85,24 +83,17 @@ func TestResolveIP(t *testing.T) {
 
 	servers, err := InitializeServerConfigs(serverConfig)
 	common.Must(err)
+	defer CloseAllServers(servers)
 
 	{
 		noAuthDialer, err := xproxy.SOCKS5("tcp", net.TCPDestination(net.LocalHostIP, serverPort).NetAddr(), nil, xproxy.Direct)
 		common.Must(err)
 		conn, err := noAuthDialer.Dial("tcp", fmt.Sprintf("google.com:%d", dest.Port))
 		common.Must(err)
+		defer conn.Close()
 
-		payload := "test payload"
-		nBytes, err := conn.Write([]byte(payload))
-		common.Must(err)
-		assert(nBytes, Equals, len(payload))
-
-		response := make([]byte, 1024)
-		nBytes, err = conn.Read(response)
-		common.Must(err)
-		assert(response[:nBytes], Equals, xor([]byte(payload)))
-		assert(conn.Close(), IsNil)
+		if err := testTCPConn2(conn, 1024, time.Second*5)(); err != nil {
+			t.Error(err)
+		}
 	}
-
-	CloseAllServers(servers)
 }
diff --git a/testing/scenarios/dokodemo_test.go b/testing/scenarios/dokodemo_test.go
index ab317d49..e48117ea 100644
--- a/testing/scenarios/dokodemo_test.go
+++ b/testing/scenarios/dokodemo_test.go
@@ -4,6 +4,8 @@ import (
 	"testing"
 	"time"
 
+	"golang.org/x/sync/errgroup"
+
 	"v2ray.com/core"
 	"v2ray.com/core/app/log"
 	"v2ray.com/core/app/proxyman"
@@ -20,7 +22,6 @@ import (
 	"v2ray.com/core/proxy/vmess/outbound"
 	"v2ray.com/core/testing/servers/tcp"
 	"v2ray.com/core/testing/servers/udp"
-	. "v2ray.com/ext/assert"
 )
 
 func TestDokodemoTCP(t *testing.T) {
@@ -121,8 +122,6 @@ func TestDokodemoTCP(t *testing.T) {
 }
 
 func TestDokodemoUDP(t *testing.T) {
-	assert := With(t)
-
 	udpServer := udp.Server{
 		MsgProcessor: xor,
 	}
@@ -198,25 +197,13 @@ func TestDokodemoUDP(t *testing.T) {
 
 	servers, err := InitializeServerConfigs(serverConfig, clientConfig)
 	common.Must(err)
+	defer CloseAllServers(servers)
 
+	var errg errgroup.Group
 	for port := clientPort; port <= clientPort+clientPortRange; port++ {
-		conn, err := net.DialUDP("udp", nil, &net.UDPAddr{
-			IP:   []byte{127, 0, 0, 1},
-			Port: int(port),
-		})
-		common.Must(err)
-
-		payload := "dokodemo request."
-		nBytes, err := conn.Write([]byte(payload))
-		common.Must(err)
-		assert(nBytes, Equals, len(payload))
-
-		response := make([]byte, 1024)
-		nBytes, err = conn.Read(response)
-		common.Must(err)
-		assert(response[:nBytes], Equals, xor([]byte(payload)))
-		assert(conn.Close(), IsNil)
+		errg.Go(testUDPConn(net.Port(port), 1024, time.Second*5))
+	}
+	if err := errg.Wait(); err != nil {
+		t.Error(err)
 	}
-
-	CloseAllServers(servers)
 }
diff --git a/testing/scenarios/feature_test.go b/testing/scenarios/feature_test.go
index 74af92ee..51caa82a 100644
--- a/testing/scenarios/feature_test.go
+++ b/testing/scenarios/feature_test.go
@@ -33,12 +33,9 @@ import (
 	"v2ray.com/core/testing/servers/tcp"
 	"v2ray.com/core/testing/servers/udp"
 	"v2ray.com/core/transport/internet"
-	. "v2ray.com/ext/assert"
 )
 
 func TestPassiveConnection(t *testing.T) {
-	assert := With(t)
-
 	tcpServer := tcp.Server{
 		MsgProcessor: xor,
 		SendFirst:    []byte("send first"),
@@ -73,6 +70,7 @@ func TestPassiveConnection(t *testing.T) {
 
 	servers, err := InitializeServerConfigs(serverConfig)
 	common.Must(err)
+	defer CloseAllServers(servers)
 
 	conn, err := net.DialTCP("tcp", nil, &net.TCPAddr{
 		IP:   []byte{127, 0, 0, 1},
@@ -84,27 +82,14 @@ func TestPassiveConnection(t *testing.T) {
 		response := make([]byte, 1024)
 		nBytes, err := conn.Read(response)
 		common.Must(err)
-		assert(string(response[:nBytes]), Equals, "send first")
+		if string(response[:nBytes]) != "send first" {
+			t.Error("unexpected first response: ", string(response[:nBytes]))
+		}
 	}
 
-	payload := "dokodemo request."
-	{
-
-		nBytes, err := conn.Write([]byte(payload))
-		common.Must(err)
-		assert(nBytes, Equals, len(payload))
+	if err := testTCPConn2(conn, 1024, time.Second*5)(); err != nil {
+		t.Error(err)
 	}
-
-	{
-		response := make([]byte, 1024)
-		nBytes, err := conn.Read(response)
-		common.Must(err)
-		assert(response[:nBytes], Equals, xor([]byte(payload)))
-	}
-
-	assert(conn.Close(), IsNil)
-
-	CloseAllServers(servers)
 }
 
 func TestProxy(t *testing.T) {
@@ -240,8 +225,6 @@ func TestProxy(t *testing.T) {
 }
 
 func TestProxyOverKCP(t *testing.T) {
-	assert := With(t)
-
 	tcpServer := tcp.Server{
 		MsgProcessor: xor,
 	}
@@ -377,30 +360,14 @@ func TestProxyOverKCP(t *testing.T) {
 
 	servers, err := InitializeServerConfigs(serverConfig, proxyConfig, clientConfig)
 	common.Must(err)
+	defer CloseAllServers(servers)
 
-	conn, err := net.DialTCP("tcp", nil, &net.TCPAddr{
-		IP:   []byte{127, 0, 0, 1},
-		Port: int(clientPort),
-	})
-	common.Must(err)
-
-	payload := "dokodemo request."
-	nBytes, err := conn.Write([]byte(payload))
-	common.Must(err)
-	assert(nBytes, Equals, len(payload))
-
-	response := make([]byte, 1024)
-	nBytes, err = conn.Read(response)
-	common.Must(err)
-	assert(response[:nBytes], Equals, xor([]byte(payload)))
-	assert(conn.Close(), IsNil)
-
-	CloseAllServers(servers)
+	if err := testTCPConn(clientPort, 1024, time.Second*5)(); err != nil {
+		t.Error(err)
+	}
 }
 
 func TestBlackhole(t *testing.T) {
-	assert := With(t)
-
 	tcpServer := tcp.Server{
 		MsgProcessor: xor,
 	}
@@ -472,35 +439,14 @@ func TestBlackhole(t *testing.T) {
 
 	servers, err := InitializeServerConfigs(serverConfig)
 	common.Must(err)
+	defer CloseAllServers(servers)
 
-	conn, err := net.DialTCP("tcp", nil, &net.TCPAddr{
-		IP:   []byte{127, 0, 0, 1},
-		Port: int(serverPort2),
-	})
-	common.Must(err)
-
-	payload := "dokodemo request."
-	{
-
-		nBytes, err := conn.Write([]byte(payload))
-		common.Must(err)
-		assert(nBytes, Equals, len(payload))
+	if err := testTCPConn(serverPort2, 1024, time.Second*5)(); err != nil {
+		t.Error(err)
 	}
-
-	{
-		response := make([]byte, 1024)
-		_, err := conn.Read(response)
-		assert(err, IsNotNil)
-	}
-
-	assert(conn.Close(), IsNil)
-
-	CloseAllServers(servers)
 }
 
 func TestForward(t *testing.T) {
-	assert := With(t)
-
 	tcpServer := tcp.Server{
 		MsgProcessor: xor,
 	}
@@ -542,31 +488,22 @@ func TestForward(t *testing.T) {
 
 	servers, err := InitializeServerConfigs(serverConfig)
 	common.Must(err)
+	defer CloseAllServers(servers)
 
 	{
 		noAuthDialer, err := xproxy.SOCKS5("tcp", net.TCPDestination(net.LocalHostIP, serverPort).NetAddr(), nil, xproxy.Direct)
 		common.Must(err)
 		conn, err := noAuthDialer.Dial("tcp", "google.com:80")
 		common.Must(err)
+		defer conn.Close()
 
-		payload := "test payload"
-		nBytes, err := conn.Write([]byte(payload))
-		common.Must(err)
-		assert(nBytes, Equals, len(payload))
-
-		response := make([]byte, 1024)
-		nBytes, err = conn.Read(response)
-		common.Must(err)
-		assert(response[:nBytes], Equals, xor([]byte(payload)))
-		assert(conn.Close(), IsNil)
+		if err := testTCPConn2(conn, 1024, time.Second*5)(); err != nil {
+			t.Error(err)
+		}
 	}
-
-	CloseAllServers(servers)
 }
 
 func TestUDPConnection(t *testing.T) {
-	assert := With(t)
-
 	udpServer := udp.Server{
 		MsgProcessor: xor,
 	}
@@ -600,56 +537,20 @@ func TestUDPConnection(t *testing.T) {
 
 	servers, err := InitializeServerConfigs(clientConfig)
 	common.Must(err)
+	CloseAllServers(servers)
 
-	{
-		conn, err := net.DialUDP("udp", nil, &net.UDPAddr{
-			IP:   []byte{127, 0, 0, 1},
-			Port: int(clientPort),
-		})
-		common.Must(err)
-
-		payload := "dokodemo request."
-		for i := 0; i < 5; i++ {
-			nBytes, err := conn.Write([]byte(payload))
-			common.Must(err)
-			assert(nBytes, Equals, len(payload))
-
-			response := make([]byte, 1024)
-			nBytes, err = conn.Read(response)
-			common.Must(err)
-			assert(response[:nBytes], Equals, xor([]byte(payload)))
-		}
-
-		assert(conn.Close(), IsNil)
+	if err := testUDPConn(clientPort, 1024, time.Second*5)(); err != nil {
+		t.Error(err)
 	}
 
 	time.Sleep(20 * time.Second)
 
-	{
-		conn, err := net.DialUDP("udp", nil, &net.UDPAddr{
-			IP:   []byte{127, 0, 0, 1},
-			Port: int(clientPort),
-		})
-		common.Must(err)
-
-		payload := "dokodemo request."
-		nBytes, err := conn.Write([]byte(payload))
-		common.Must(err)
-		assert(nBytes, Equals, len(payload))
-
-		response := make([]byte, 1024)
-		nBytes, err = conn.Read(response)
-		common.Must(err)
-		assert(response[:nBytes], Equals, xor([]byte(payload)))
-		assert(conn.Close(), IsNil)
+	if err := testUDPConn(clientPort, 1024, time.Second*5)(); err != nil {
+		t.Error(err)
 	}
-
-	CloseAllServers(servers)
 }
 
 func TestDomainSniffing(t *testing.T) {
-	assert := With(t)
-
 	sniffingPort := tcp.PickPort()
 	httpPort := tcp.PickPort()
 	serverConfig := &core.Config{
@@ -722,6 +623,7 @@ func TestDomainSniffing(t *testing.T) {
 
 	servers, err := InitializeServerConfigs(serverConfig)
 	common.Must(err)
+	defer CloseAllServers(servers)
 
 	{
 		transport := &http.Transport{
@@ -736,17 +638,14 @@ func TestDomainSniffing(t *testing.T) {
 
 		resp, err := client.Get("https://www.github.com/")
 		common.Must(err)
-		assert(resp.StatusCode, Equals, 200)
-
-		assert(resp.Write(ioutil.Discard), IsNil)
+		if resp.StatusCode != 200 {
+			t.Error("unexpected status code: ", resp.StatusCode)
+		}
+		common.Must(resp.Write(ioutil.Discard))
 	}
-
-	CloseAllServers(servers)
 }
 
 func TestDialV2Ray(t *testing.T) {
-	assert := With(t)
-
 	tcpServer := tcp.Server{
 		MsgProcessor: xor,
 	}
@@ -822,23 +721,16 @@ func TestDialV2Ray(t *testing.T) {
 
 	servers, err := InitializeServerConfigs(serverConfig)
 	common.Must(err)
+	defer CloseAllServers(servers)
 
 	client, err := core.New(clientConfig)
 	common.Must(err)
 
 	conn, err := core.Dial(context.Background(), client, dest)
 	common.Must(err)
+	defer conn.Close()
 
-	payload := "commander request."
-	nBytes, err := conn.Write([]byte(payload))
-	common.Must(err)
-	assert(nBytes, Equals, len(payload))
-
-	response := make([]byte, 1024)
-	nBytes, err = conn.Read(response)
-	common.Must(err)
-	assert(response[:nBytes], Equals, xor([]byte(payload)))
-	assert(conn.Close(), IsNil)
-
-	CloseAllServers(servers)
+	if err := testTCPConn2(conn, 1024, time.Second*5)(); err != nil {
+		t.Error(err)
+	}
 }
diff --git a/testing/scenarios/shadowsocks_test.go b/testing/scenarios/shadowsocks_test.go
index 87939f38..1f2a3ae9 100644
--- a/testing/scenarios/shadowsocks_test.go
+++ b/testing/scenarios/shadowsocks_test.go
@@ -2,7 +2,6 @@ package scenarios
 
 import (
 	"crypto/rand"
-	"sync"
 	"testing"
 	"time"
 
@@ -23,7 +22,6 @@ import (
 	"v2ray.com/core/proxy/shadowsocks"
 	"v2ray.com/core/testing/servers/tcp"
 	"v2ray.com/core/testing/servers/udp"
-	. "v2ray.com/ext/assert"
 )
 
 func TestShadowsocksAES256TCP(t *testing.T) {
@@ -538,8 +536,6 @@ func TestShadowsocksAES256GCMTCP(t *testing.T) {
 }
 
 func TestShadowsocksAES128GCMUDP(t *testing.T) {
-	assert := With(t)
-
 	udpServer := udp.Server{
 		MsgProcessor: xor,
 	}
@@ -626,38 +622,18 @@ func TestShadowsocksAES128GCMUDP(t *testing.T) {
 
 	servers, err := InitializeServerConfigs(serverConfig, clientConfig)
 	common.Must(err)
+	defer CloseAllServers(servers)
 
-	var wg sync.WaitGroup
-	wg.Add(10)
+	var errg errgroup.Group
 	for i := 0; i < 10; i++ {
-		go func() {
-			conn, err := net.DialUDP("udp", nil, &net.UDPAddr{
-				IP:   []byte{127, 0, 0, 1},
-				Port: int(clientPort),
-			})
-			common.Must(err)
-
-			payload := make([]byte, 1024)
-			rand.Read(payload)
-
-			nBytes, err := conn.Write([]byte(payload))
-			common.Must(err)
-			assert(nBytes, Equals, len(payload))
-
-			response := readFrom(conn, time.Second*5, 1024)
-			assert(response, Equals, xor([]byte(payload)))
-			assert(conn.Close(), IsNil)
-			wg.Done()
-		}()
+		errg.Go(testUDPConn(clientPort, 1024, time.Second*5))
+	}
+	if err := errg.Wait(); err != nil {
+		t.Error(err)
 	}
-	wg.Wait()
-
-	CloseAllServers(servers)
 }
 
 func TestShadowsocksAES128GCMUDPMux(t *testing.T) {
-	assert := With(t)
-
 	udpServer := udp.Server{
 		MsgProcessor: xor,
 	}
@@ -750,33 +726,15 @@ func TestShadowsocksAES128GCMUDPMux(t *testing.T) {
 
 	servers, err := InitializeServerConfigs(serverConfig, clientConfig)
 	common.Must(err)
+	defer CloseAllServers(servers)
 
-	var wg sync.WaitGroup
-	wg.Add(10)
+	var errg errgroup.Group
 	for i := 0; i < 10; i++ {
-		go func() {
-			conn, err := net.DialUDP("udp", nil, &net.UDPAddr{
-				IP:   []byte{127, 0, 0, 1},
-				Port: int(clientPort),
-			})
-			common.Must(err)
-
-			payload := make([]byte, 1024)
-			rand.Read(payload)
-
-			nBytes, err := conn.Write([]byte(payload))
-			common.Must(err)
-			assert(nBytes, Equals, len(payload))
-
-			response := readFrom(conn, time.Second*5, 1024)
-			assert(response, Equals, xor([]byte(payload)))
-			assert(conn.Close(), IsNil)
-			wg.Done()
-		}()
+		errg.Go(testUDPConn(clientPort, 1024, time.Second*5))
+	}
+	if err := errg.Wait(); err != nil {
+		t.Error(err)
 	}
-	wg.Wait()
-
-	CloseAllServers(servers)
 }
 
 func TestShadowsocksNone(t *testing.T) {
diff --git a/testing/scenarios/socks_test.go b/testing/scenarios/socks_test.go
index 4cbeac8b..9763dbc6 100644
--- a/testing/scenarios/socks_test.go
+++ b/testing/scenarios/socks_test.go
@@ -20,7 +20,6 @@ import (
 	"v2ray.com/core/proxy/socks"
 	"v2ray.com/core/testing/servers/tcp"
 	"v2ray.com/core/testing/servers/udp"
-	. "v2ray.com/ext/assert"
 )
 
 func TestSocksBridgeTCP(t *testing.T) {
@@ -105,8 +104,6 @@ func TestSocksBridgeTCP(t *testing.T) {
 }
 
 func TestSocksBridageUDP(t *testing.T) {
-	assert := With(t)
-
 	udpServer := udp.Server{
 		MsgProcessor: xor,
 	}
@@ -180,30 +177,14 @@ func TestSocksBridageUDP(t *testing.T) {
 
 	servers, err := InitializeServerConfigs(serverConfig, clientConfig)
 	common.Must(err)
+	defer CloseAllServers(servers)
 
-	conn, err := net.DialUDP("udp", nil, &net.UDPAddr{
-		IP:   []byte{127, 0, 0, 1},
-		Port: int(clientPort),
-	})
-	common.Must(err)
-
-	payload := "dokodemo request."
-	nBytes, err := conn.Write([]byte(payload))
-	common.Must(err)
-	assert(nBytes, Equals, len(payload))
-
-	response := make([]byte, 1024)
-	nBytes, err = conn.Read(response)
-	common.Must(err)
-	assert(response[:nBytes], Equals, xor([]byte(payload)))
-	assert(conn.Close(), IsNil)
-
-	CloseAllServers(servers)
+	if err := testUDPConn(clientPort, 1024, time.Second*5)(); err != nil {
+		t.Error(err)
+	}
 }
 
 func TestSocksBridageUDPWithRouting(t *testing.T) {
-	assert := With(t)
-
 	udpServer := udp.Server{
 		MsgProcessor: xor,
 	}
@@ -283,30 +264,14 @@ func TestSocksBridageUDPWithRouting(t *testing.T) {
 
 	servers, err := InitializeServerConfigs(serverConfig, clientConfig)
 	common.Must(err)
+	defer CloseAllServers(servers)
 
-	conn, err := net.DialUDP("udp", nil, &net.UDPAddr{
-		IP:   []byte{127, 0, 0, 1},
-		Port: int(clientPort),
-	})
-	common.Must(err)
-
-	payload := "dokodemo request."
-	nBytes, err := conn.Write([]byte(payload))
-	common.Must(err)
-	assert(nBytes, Equals, len(payload))
-
-	response := make([]byte, 1024)
-	nBytes, err = conn.Read(response)
-	common.Must(err)
-	assert(response[:nBytes], Equals, xor([]byte(payload)))
-	assert(conn.Close(), IsNil)
-
-	CloseAllServers(servers)
+	if err := testUDPConn(clientPort, 1024, time.Second*5)(); err != nil {
+		t.Error(err)
+	}
 }
 
 func TestSocksConformance(t *testing.T) {
-	assert := With(t)
-
 	tcpServer := tcp.Server{
 		MsgProcessor: xor,
 	}
@@ -356,23 +321,18 @@ func TestSocksConformance(t *testing.T) {
 
 	servers, err := InitializeServerConfigs(serverConfig)
 	common.Must(err)
+	defer CloseAllServers(servers)
 
 	{
 		noAuthDialer, err := xproxy.SOCKS5("tcp", net.TCPDestination(net.LocalHostIP, noAuthPort).NetAddr(), nil, xproxy.Direct)
 		common.Must(err)
 		conn, err := noAuthDialer.Dial("tcp", dest.NetAddr())
 		common.Must(err)
+		defer conn.Close()
 
-		payload := "test payload"
-		nBytes, err := conn.Write([]byte(payload))
-		common.Must(err)
-		assert(nBytes, Equals, len(payload))
-
-		response := make([]byte, 1024)
-		nBytes, err = conn.Read(response)
-		common.Must(err)
-		assert(response[:nBytes], Equals, xor([]byte(payload)))
-		assert(conn.Close(), IsNil)
+		if err := testTCPConn2(conn, 1024, time.Second*5)(); err != nil {
+			t.Error(err)
+		}
 	}
 
 	{
@@ -380,52 +340,32 @@ func TestSocksConformance(t *testing.T) {
 		common.Must(err)
 		conn, err := authDialer.Dial("tcp", dest.NetAddr())
 		common.Must(err)
+		defer conn.Close()
 
-		payload := "test payload"
-		nBytes, err := conn.Write([]byte(payload))
-		common.Must(err)
-		assert(nBytes, Equals, len(payload))
-
-		response := make([]byte, 1024)
-		nBytes, err = conn.Read(response)
-		common.Must(err)
-		assert(response[:nBytes], Equals, xor([]byte(payload)))
-		assert(conn.Close(), IsNil)
+		if err := testTCPConn2(conn, 1024, time.Second*5)(); err != nil {
+			t.Error(err)
+		}
 	}
 
 	{
 		dialer := socks4.DialSocksProxy(socks4.SOCKS4, net.TCPDestination(net.LocalHostIP, noAuthPort).NetAddr())
 		conn, err := dialer("tcp", dest.NetAddr())
 		common.Must(err)
+		defer conn.Close()
 
-		payload := "test payload"
-		nBytes, err := conn.Write([]byte(payload))
-		common.Must(err)
-		assert(nBytes, Equals, len(payload))
-
-		response := make([]byte, 1024)
-		nBytes, err = conn.Read(response)
-		common.Must(err)
-		assert(response[:nBytes], Equals, xor([]byte(payload)))
-		assert(conn.Close(), IsNil)
+		if err := testTCPConn2(conn, 1024, time.Second*5)(); err != nil {
+			t.Error(err)
+		}
 	}
 
 	{
 		dialer := socks4.DialSocksProxy(socks4.SOCKS4A, net.TCPDestination(net.LocalHostIP, noAuthPort).NetAddr())
 		conn, err := dialer("tcp", net.TCPDestination(net.LocalHostDomain, tcpServer.Port).NetAddr())
 		common.Must(err)
+		defer conn.Close()
 
-		payload := "test payload"
-		nBytes, err := conn.Write([]byte(payload))
-		common.Must(err)
-		assert(nBytes, Equals, len(payload))
-
-		response := make([]byte, 1024)
-		nBytes, err = conn.Read(response)
-		common.Must(err)
-		assert(response[:nBytes], Equals, xor([]byte(payload)))
-		assert(conn.Close(), IsNil)
+		if err := testTCPConn2(conn, 1024, time.Second*5)(); err != nil {
+			t.Error(err)
+		}
 	}
-
-	CloseAllServers(servers)
 }
diff --git a/testing/scenarios/vmess_test.go b/testing/scenarios/vmess_test.go
index 0838f764..c080f3b4 100644
--- a/testing/scenarios/vmess_test.go
+++ b/testing/scenarios/vmess_test.go
@@ -1,9 +1,7 @@
 package scenarios
 
 import (
-	"crypto/rand"
 	"os"
-	"sync"
 	"testing"
 	"time"
 
@@ -26,7 +24,6 @@ import (
 	"v2ray.com/core/testing/servers/udp"
 	"v2ray.com/core/transport/internet"
 	"v2ray.com/core/transport/internet/kcp"
-	. "v2ray.com/ext/assert"
 )
 
 func TestVMessDynamicPort(t *testing.T) {
@@ -364,8 +361,6 @@ func TestVMessGCMReadv(t *testing.T) {
 }
 
 func TestVMessGCMUDP(t *testing.T) {
-	assert := With(t)
-
 	udpServer := udp.Server{
 		MsgProcessor: xor,
 	}
@@ -457,43 +452,15 @@ func TestVMessGCMUDP(t *testing.T) {
 
 	servers, err := InitializeServerConfigs(serverConfig, clientConfig)
 	common.Must(err)
-
-	var wg sync.WaitGroup
-	wg.Add(10)
-	for i := 0; i < 10; i++ {
-		go func() {
-			conn, err := net.DialUDP("udp", nil, &net.UDPAddr{
-				IP:   []byte{127, 0, 0, 1},
-				Port: int(clientPort),
-			})
-			common.Must(err)
-
-			payload := make([]byte, 1024)
-			rand.Read(payload)
-
-			nBytes, err := conn.Write([]byte(payload))
-			common.Must(err)
-			assert(nBytes, Equals, len(payload))
-
-			payload1 := make([]byte, 1024)
-			rand.Read(payload1)
-			nBytes, err = conn.Write([]byte(payload1))
-			common.Must(err)
-			assert(nBytes, Equals, len(payload1))
-
-			response := readFrom(conn, time.Second*5, 1024)
-			assert(response, Equals, xor([]byte(payload)))
-
-			response = readFrom(conn, time.Second*5, 1024)
-			assert(response, Equals, xor([]byte(payload1)))
-
-			assert(conn.Close(), IsNil)
-			wg.Done()
-		}()
-	}
-	wg.Wait()
-
 	CloseAllServers(servers)
+
+	var errg errgroup.Group
+	for i := 0; i < 10; i++ {
+		errg.Go(testTCPConn(clientPort, 1024, time.Second*5))
+	}
+	if err := errg.Wait(); err != nil {
+		t.Error(err)
+	}
 }
 
 func TestVMessChacha20(t *testing.T) {
@@ -1076,8 +1043,6 @@ func TestVMessGCMMux(t *testing.T) {
 }
 
 func TestVMessGCMMuxUDP(t *testing.T) {
-	assert := With(t)
-
 	tcpServer := tcp.Server{
 		MsgProcessor: xor,
 	}
@@ -1196,71 +1161,17 @@ func TestVMessGCMMuxUDP(t *testing.T) {
 
 	servers, err := InitializeServerConfigs(serverConfig, clientConfig)
 	common.Must(err)
+	defer CloseAllServers(servers)
 
 	for range "abcd" {
-		var wg sync.WaitGroup
-		const nConnection = 16
-		wg.Add(nConnection * 2)
-		for i := 0; i < nConnection; i++ {
-			go func() {
-				conn, err := net.DialTCP("tcp", nil, &net.TCPAddr{
-					IP:   []byte{127, 0, 0, 1},
-					Port: int(clientPort),
-				})
-				common.Must(err)
-
-				payload := make([]byte, 10240)
-				rand.Read(payload)
-
-				xorpayload := xor(payload)
-
-				nBytes, err := conn.Write(payload)
-				common.Must(err)
-				assert(nBytes, Equals, len(payload))
-
-				response := readFrom(conn, time.Second*20, 10240)
-				assert(response, Equals, xorpayload)
-				assert(conn.Close(), IsNil)
-				wg.Done()
-			}()
+		var errg errgroup.Group
+		for i := 0; i < 16; i++ {
+			errg.Go(testTCPConn(clientPort, 10240, time.Second*20))
+			errg.Go(testUDPConn(clientUDPPort, 1024, time.Second*10))
 		}
-		for i := 0; i < nConnection; i++ {
-			go func() {
-				conn, err := net.DialUDP("udp", nil, &net.UDPAddr{
-					IP:   []byte{127, 0, 0, 1},
-					Port: int(clientUDPPort),
-				})
-				common.Must(err)
-
-				conn.SetDeadline(time.Now().Add(time.Second * 10))
-
-				payload := make([]byte, 1024)
-				rand.Read(payload)
-
-				xorpayload := xor(payload)
-
-				for j := 0; j < 2; j++ {
-					nBytes, _, err := conn.WriteMsgUDP(payload, nil, nil)
-					common.Must(err)
-					assert(nBytes, Equals, len(payload))
-				}
-
-				response := make([]byte, 1024)
-				oob := make([]byte, 16)
-				for j := 0; j < 2; j++ {
-					nBytes, _, _, _, err := conn.ReadMsgUDP(response, oob)
-					common.Must(err)
-					assert(nBytes, Equals, 1024)
-					assert(response, Equals, xorpayload)
-				}
-
-				assert(conn.Close(), IsNil)
-				wg.Done()
-			}()
+		if err := errg.Wait(); err != nil {
+			t.Error(err)
 		}
-		wg.Wait()
 		time.Sleep(time.Second)
 	}
-
-	CloseAllServers(servers)
 }
diff --git a/transport/internet/headers/http/http_test.go b/transport/internet/headers/http/http_test.go
index 2502c83a..0aa0165f 100644
--- a/transport/internet/headers/http/http_test.go
+++ b/transport/internet/headers/http/http_test.go
@@ -11,31 +11,30 @@ import (
 	"v2ray.com/core/common/buf"
 	"v2ray.com/core/common/net"
 	. "v2ray.com/core/transport/internet/headers/http"
-	. "v2ray.com/ext/assert"
 )
 
 func TestReaderWriter(t *testing.T) {
-	assert := With(t)
-
 	cache := buf.New()
 	b := buf.New()
 	common.Must2(b.WriteString("abcd" + ENDING))
 	writer := NewHeaderWriter(b)
 	err := writer.Write(cache)
 	common.Must(err)
-	assert(cache.Len(), Equals, int32(8))
+	if v := cache.Len(); v != 8 {
+		t.Error("cache len: ", v)
+	}
 	_, err = cache.Write([]byte{'e', 'f', 'g'})
 	common.Must(err)
 
 	reader := &HeaderReader{}
 	buffer, err := reader.Read(cache)
 	common.Must(err)
-	assert(buffer.Bytes(), Equals, []byte{'e', 'f', 'g'})
+	if buffer.String() != "efg" {
+		t.Error("buffer: ", buffer.String())
+	}
 }
 
 func TestRequestHeader(t *testing.T) {
-	assert := With(t)
-
 	auth, err := NewHttpAuthenticator(context.Background(), &Config{
 		Request: &RequestConfig{
 			Uri: []string{"/"},
@@ -53,7 +52,9 @@ func TestRequestHeader(t *testing.T) {
 	err = auth.GetClientWriter().Write(cache)
 	common.Must(err)
 
-	assert(cache.String(), Equals, "GET / HTTP/1.1\r\nTest: Value\r\n\r\n")
+	if cache.String() != "GET / HTTP/1.1\r\nTest: Value\r\n\r\n" {
+		t.Error("cache: ", cache.String())
+	}
 }
 
 func TestLongRequestHeader(t *testing.T) {
@@ -71,8 +72,6 @@ func TestLongRequestHeader(t *testing.T) {
 }
 
 func TestConnection(t *testing.T) {
-	assert := With(t)
-
 	auth, err := NewHttpAuthenticator(context.Background(), &Config{
 		Request: &RequestConfig{
 			Method: &Method{Value: "Post"},
@@ -110,7 +109,9 @@ func TestConnection(t *testing.T) {
 		b := make([]byte, 256)
 		for {
 			n, err := authConn.Read(b)
-			common.Must(err)
+			if err != nil {
+				break
+			}
 			_, err = authConn.Write(b[:n])
 			common.Must(err)
 		}
@@ -120,6 +121,8 @@ func TestConnection(t *testing.T) {
 	common.Must(err)
 
 	authConn := auth.Client(conn)
+	defer authConn.Close()
+
 	authConn.Write([]byte("Test payload"))
 	authConn.Write([]byte("Test payload 2"))
 
@@ -136,5 +139,7 @@ func TestConnection(t *testing.T) {
 		}
 	}
 
-	assert(string(actualResponse[:totalBytes]), Equals, expectedResponse)
+	if string(actualResponse[:totalBytes]) != expectedResponse {
+		t.Error("response: ", string(actualResponse[:totalBytes]))
+	}
 }
diff --git a/transport/internet/headers/tls/dtls_test.go b/transport/internet/headers/tls/dtls_test.go
index da8b2a9c..e26aab37 100644
--- a/transport/internet/headers/tls/dtls_test.go
+++ b/transport/internet/headers/tls/dtls_test.go
@@ -7,12 +7,9 @@ import (
 	"v2ray.com/core/common"
 	"v2ray.com/core/common/buf"
 	. "v2ray.com/core/transport/internet/headers/tls"
-	. "v2ray.com/ext/assert"
 )
 
 func TestDTLSWrite(t *testing.T) {
-	assert := With(t)
-
 	content := []byte{'a', 'b', 'c', 'd', 'e', 'f', 'g'}
 	dtlsRaw, err := New(context.Background(), &PacketConfig{})
 	common.Must(err)
@@ -23,5 +20,7 @@ func TestDTLSWrite(t *testing.T) {
 	dtls.Serialize(payload.Extend(dtls.Size()))
 	payload.Write(content)
 
-	assert(payload.Len(), Equals, int32(len(content))+dtls.Size())
+	if payload.Len() != int32(len(content))+dtls.Size() {
+		t.Error("payload len: ", payload.Len(), " want ", int32(len(content))+dtls.Size())
+	}
 }
diff --git a/transport/internet/kcp/connection_test.go b/transport/internet/kcp/connection_test.go
index b09298de..0d80dd22 100644
--- a/transport/internet/kcp/connection_test.go
+++ b/transport/internet/kcp/connection_test.go
@@ -7,7 +7,6 @@ import (
 
 	"v2ray.com/core/common/buf"
 	. "v2ray.com/core/transport/internet/kcp"
-	. "v2ray.com/ext/assert"
 )
 
 type NoOpCloser int
@@ -17,8 +16,6 @@ func (NoOpCloser) Close() error {
 }
 
 func TestConnectionReadTimeout(t *testing.T) {
-	assert := With(t)
-
 	conn := NewConnection(ConnMetadata{Conversation: 1}, &KCPPacketWriter{
 		Writer: buf.DiscardBytes,
 	}, NoOpCloser(0), &Config{})
@@ -26,17 +23,16 @@ func TestConnectionReadTimeout(t *testing.T) {
 
 	b := make([]byte, 1024)
 	nBytes, err := conn.Read(b)
-	assert(nBytes, Equals, 0)
-	assert(err, IsNotNil)
+	if nBytes != 0 || err == nil {
+		t.Error("unexpected read: ", nBytes, err)
+	}
 
 	conn.Terminate()
 }
 
 func TestConnectionInterface(t *testing.T) {
-	assert := With(t)
-
-	assert((*Connection)(nil), Implements, (*io.Writer)(nil))
-	assert((*Connection)(nil), Implements, (*io.Reader)(nil))
-	assert((*Connection)(nil), Implements, (*buf.Reader)(nil))
-	assert((*Connection)(nil), Implements, (*buf.Writer)(nil))
+	_ = (io.Writer)(new(Connection))
+	_ = (io.Reader)(new(Connection))
+	_ = (buf.Reader)(new(Connection))
+	_ = (buf.Writer)(new(Connection))
 }
diff --git a/transport/internet/tcp/sockopt_linux_test.go b/transport/internet/tcp/sockopt_linux_test.go
index ce4fa7dc..b4c77638 100644
--- a/transport/internet/tcp/sockopt_linux_test.go
+++ b/transport/internet/tcp/sockopt_linux_test.go
@@ -11,12 +11,9 @@ import (
 	"v2ray.com/core/testing/servers/tcp"
 	"v2ray.com/core/transport/internet"
 	. "v2ray.com/core/transport/internet/tcp"
-	. "v2ray.com/ext/assert"
 )
 
 func TestGetOriginalDestination(t *testing.T) {
-	assert := With(t)
-
 	tcpServer := tcp.Server{}
 	dest, err := tcpServer.Start()
 	common.Must(err)
@@ -29,5 +26,7 @@ func TestGetOriginalDestination(t *testing.T) {
 	defer conn.Close()
 
 	originalDest, err := GetOriginalDestination(conn)
-	assert(dest == originalDest || strings.Contains(err.Error(), "failed to call getsockopt"), IsTrue)
+	if !(dest == originalDest || strings.Contains(err.Error(), "failed to call getsockopt")) {
+		t.Error("unexpected state")
+	}
 }
diff --git a/transport/internet/udp/dispatcher_test.go b/transport/internet/udp/dispatcher_test.go
index 929ac501..e75aa5a1 100644
--- a/transport/internet/udp/dispatcher_test.go
+++ b/transport/internet/udp/dispatcher_test.go
@@ -14,7 +14,6 @@ import (
 	"v2ray.com/core/transport"
 	. "v2ray.com/core/transport/internet/udp"
 	"v2ray.com/core/transport/pipe"
-	. "v2ray.com/ext/assert"
 )
 
 type TestDispatcher struct {
@@ -38,8 +37,6 @@ func (*TestDispatcher) Type() interface{} {
 }
 
 func TestSameDestinationDispatching(t *testing.T) {
-	assert := With(t)
-
 	ctx, cancel := context.WithCancel(context.Background())
 	uplinkReader, uplinkWriter := pipe.New(pipe.WithSizeLimit(1024))
 	downlinkReader, downlinkWriter := pipe.New(pipe.WithSizeLimit(1024))
@@ -80,6 +77,10 @@ func TestSameDestinationDispatching(t *testing.T) {
 	time.Sleep(time.Second)
 	cancel()
 
-	assert(count, Equals, uint32(1))
-	assert(atomic.LoadUint32(&msgCount), Equals, uint32(6))
+	if count != 1 {
+		t.Error("count: ", count)
+	}
+	if v := atomic.LoadUint32(&msgCount); v != 6 {
+		t.Error("msgCount: ", v)
+	}
 }