diff --git a/transport/transport_test.go b/transport/transport_test.go
index 1a284072..39792e4a 100644
--- a/transport/transport_test.go
+++ b/transport/transport_test.go
@@ -97,7 +97,8 @@ func (h *testStreamHandler) handleStreamSuspension(s *Stream) {
 	<-s.ctx.Done()
 }
 
-func (s *server) Start(useTLS bool, port int, maxStreams uint32, suspend bool) {
+// start starts server. Other goroutines should block on s.readyChan for futher operations.
+func (s *server) start(useTLS bool, port int, maxStreams uint32, suspend bool) {
 	var err error
 	if port == 0 {
 		s.lis, err = net.Listen("tcp", ":0")
@@ -119,10 +120,10 @@ func (s *server) Start(useTLS bool, port int, maxStreams uint32, suspend bool) {
 		log.Fatalf("failed to parse listener address: %v", err)
 	}
 	s.port = p
+	s.conns = make(map[ServerTransport]bool)
 	if s.readyChan != nil {
 		close(s.readyChan)
 	}
-	s.conns = make(map[ServerTransport]bool)
 	for {
 		conn, err := s.lis.Accept()
 		if err != nil {
@@ -149,7 +150,7 @@ func (s *server) Start(useTLS bool, port int, maxStreams uint32, suspend bool) {
 	}
 }
 
-func (s *server) Wait(t *testing.T, timeout time.Duration) {
+func (s *server) wait(t *testing.T, timeout time.Duration) {
 	select {
 	case <-s.readyChan:
 	case <-time.After(timeout):
@@ -157,20 +158,20 @@ func (s *server) Wait(t *testing.T, timeout time.Duration) {
 	}
 }
 
-func (s *server) Close() {
-	// Keep consistent with closeServer().
+func (s *server) stop() {
 	s.lis.Close()
 	s.mu.Lock()
 	for c := range s.conns {
 		c.Close()
 	}
+	s.conns = nil
 	s.mu.Unlock()
 }
 
 func setUp(t *testing.T, useTLS bool, port int, maxStreams uint32, suspend bool) (*server, ClientTransport) {
 	server := &server{readyChan: make(chan bool)}
-	go server.Start(useTLS, port, maxStreams, suspend)
-	server.Wait(t, 2*time.Second)
+	go server.start(useTLS, port, maxStreams, suspend)
+	server.wait(t, 2*time.Second)
 	addr := "localhost:" + server.port
 	var (
 		ct      ClientTransport
@@ -231,24 +232,12 @@ func TestClientSendAndReceive(t *testing.T) {
 		t.Fatalf("Error: %v; want <EOF>", recvErr)
 	}
 	ct.Close()
-	server.Close()
+	server.stop()
 }
 
 func TestClientErrorNotify(t *testing.T) {
 	server, ct := setUp(t, true, 0, math.MaxUint32, false)
-	callHdr := &CallHdr{
-		Host:   "localhost",
-		Method: "foo.Small",
-	}
-	s, err := ct.NewStream(context.Background(), callHdr)
-	if err != nil {
-		t.Fatalf("failed to open stream: %v", err)
-	}
-	if s.id != 1 {
-		t.Fatalf("wrong stream id: %d", s.id)
-	}
-	// Tear down the server.
-	go server.Close()
+	go server.stop()
 	// ct.reader should detect the error and activate ct.Error().
 	<-ct.Error()
 	ct.Close()
@@ -284,7 +273,7 @@ func TestClientMix(t *testing.T) {
 	s, ct := setUp(t, true, 0, math.MaxUint32, false)
 	go func(s *server) {
 		time.Sleep(5 * time.Second)
-		s.Close()
+		s.stop()
 	}(s)
 	go func(ct ClientTransport) {
 		<-ct.Error()
@@ -300,7 +289,7 @@ func TestExceedMaxStreamsLimit(t *testing.T) {
 	server, ct := setUp(t, true, 0, 1, false)
 	defer func() {
 		ct.Close()
-		server.Close()
+		server.stop()
 	}()
 	callHdr := &CallHdr{
 		Host:   "localhost",
@@ -375,7 +364,7 @@ func TestLargeMessage(t *testing.T) {
 	}
 	wg.Wait()
 	ct.Close()
-	server.Close()
+	server.stop()
 }
 
 func TestLargeMessageSuspension(t *testing.T) {
@@ -397,7 +386,7 @@ func TestLargeMessageSuspension(t *testing.T) {
 		t.Fatalf("Write got %v, want %v", err, expectedErr)
 	}
 	ct.Close()
-	server.Close()
+	server.stop()
 }
 
 func TestStreamContext(t *testing.T) {