SGSN: introduce NS tests

Similiar to the PCU_Tests_NS introduce SGSN_Tests_NS.

Change-Id: Ib2bffbb110961474928f35d212cb492d4b6fdee0
diff --git a/sgsn/SGSN_Tests.ttcn b/sgsn/SGSN_Tests.ttcn
index abbcb64..b42020d 100644
--- a/sgsn/SGSN_Tests.ttcn
+++ b/sgsn/SGSN_Tests.ttcn
@@ -12,6 +12,7 @@
  */
 
 friend module SGSN_Tests_Iu;
+friend module SGSN_Tests_NS;
 
 import from General_Types all;
 import from Osmocom_Types all;
@@ -257,7 +258,7 @@
 	vc_GTP.start(GTP_Emulation.main(gtp_cfg));
 }
 
-private function f_init_vty() runs on test_CT {
+friend function f_init_vty() runs on test_CT {
 	map(self:SGSNVTY, system:SGSNVTY);
 	f_vty_set_prompts(SGSNVTY);
 	f_vty_transceive(SGSNVTY, "enable");