diff --git a/server/modbus.go b/server/modbus.go
index 77fcba1..b6ce6b2 100644
--- a/server/modbus.go
+++ b/server/modbus.go
@@ -7,13 +7,14 @@ import (
 	"github.com/aldas/go-modbus-client/packet"
 )
 
-// modbusTCPAssembler assembles read data into complete packets and calls ModbusHandler with assembled packet
-type modbusTCPAssembler struct {
+// ModbusTCPAssembler assembles read data into complete packets and calls ModbusHandler with assembled packet
+type ModbusTCPAssembler struct {
 	handler  ModbusHandler
 	received bytes.Buffer
 }
 
-func (m *modbusTCPAssembler) ReceiveRead(ctx context.Context, received []byte, bytesRead int) (response []byte, closeConnection bool) {
+// ReceiveRead assembles read byte until full TCP packet is formed or return an error when received data does not look like TCP packet
+func (m *ModbusTCPAssembler) ReceiveRead(ctx context.Context, received []byte, bytesRead int) (response []byte, closeConnection bool) {
 	m.received.Write(received)
 
 	n, err := packet.LooksLikeModbusTCP(m.received.Bytes(), false)
diff --git a/server/server.go b/server/server.go
index 029b85c..82dbab9 100644
--- a/server/server.go
+++ b/server/server.go
@@ -112,7 +112,7 @@ type ContextRemoteAddr struct{}
 func (s *Server) serve(ctx context.Context, listener net.Listener, handler ModbusHandler) error {
 	if s.AssemblerCreatorFunc == nil {
 		s.AssemblerCreatorFunc = func(handler ModbusHandler) PacketAssembler {
-			return &modbusTCPAssembler{handler: handler}
+			return &ModbusTCPAssembler{handler: handler}
 		}
 	}
 	onErrorFunc := s.OnErrorFunc
diff --git a/server/server_test.go b/server/server_test.go
index 00a5c83..28cb229 100644
--- a/server/server_test.go
+++ b/server/server_test.go
@@ -33,7 +33,7 @@ func TestRequestToServer(t *testing.T) {
 
 	// we start the server and listen for incoming connections/data in separate goroutine. ListenAndServe is blocking call.
 	go func() {
-		err := s.ListenAndServe(ctx, "localhost:5020", mbs)
+		err := s.ListenAndServe(ctx, "localhost:0", mbs)
 		if err != nil && !errors.Is(err, ErrServerClosed) {
 			assert.NoError(t, err)
 		}