Externalize in mock class

core-writer/test/test_UdpReceiver.cpp

@@ -2,16 +2,8 @@
 #include <jungfrau.hpp>
 #include "gtest/gtest.h"
 #include "UdpReceiver.hpp"
+#include "mock/udp.hpp"
 
-sockaddr_in get_server_address(uint16_t udp_port)
-{
-    sockaddr_in server_address = {0};
-    server_address.sin_family = AF_INET;
-    server_address.sin_addr.s_addr = INADDR_ANY;
-    server_address.sin_port = htons(udp_port);
-
-    return server_address;
-}
 
 TEST(UdpReceiver, simple_recv)
 {