use correct packages

tcp-mux_test.go

@@ -25,12 +25,19 @@ func TestTcpHelpers(t *testing.T) {
 		log.Printf("Received call: %s\n", string(data))
 		return 3, []byte("Hello, client!"), nil
 	})
+	server.HandleCall(Ping, func(data []byte) (uint32, []byte, error) {
+		return Pong, nil, nil
+	})
 
 	client.SendPacket(1, []byte("Hello, world!"))
 	answer, err := client.Call(2, 3, []byte("Hello, server!"))
 	if err != nil {
 		t.Errorf("Error calling: %v\n", err)
 	}
+	_, err = client.Call(Ping, Pong, nil)
+	if err != nil {
+		t.Errorf("Error calling: %v\n", err)
+	}
 	if string(answer) != "Hello, client!" {
 		t.Errorf("Expected answer 'Hello, client!', got %s\n", string(answer))
 	}