Added test code for the new functions tcp_listening_v4 and tcp_listening_v6 as well as trying to open two acceptors on the same port.

Author: Medo42

examples/unittests/Scripts/testTcpConnecting.gml

@@ -1,7 +1,15 @@
-var acceptor, sock1, sock2;
+var acceptor, acceptor2, sock1, sock2;
 
 acceptor = tcp_listen(0);
 assertFalse(socket_has_error(acceptor), "Error creating listening socket: "+socket_error(acceptor));
+assertTrue(tcp_listening_v4(acceptor), "Acceptor not working for IPv4: " + socket_error(acceptor));
+assertTrue(tcp_listening_v6(acceptor), "Acceptor not working for IPv6: " + socket_error(acceptor));
+
+acceptor2 = tcp_listen(socket_local_port(acceptor));
+assertFalse(tcp_listening_v4(acceptor2), "Acceptor listening to IPv4 port which should already be in use!");
+assertFalse(tcp_listening_v6(acceptor2), "Acceptor listening to IPv6 port which should already be in use!");
+assertTrue(socket_has_error(acceptor2), "Acceptor not reporting error even though it is neither listening to IPv4 nor IPv6!");
+socket_destroy(acceptor2);
 
 if(!socket_has_error(acceptor)) {
     sock1 = tcp_connect("127.0.0.1", socket_local_port(acceptor));