gbproxy: Add testcase for MS-REGISTRATION ENQUIRY

The test case fails with current master, as osmo-gbproxy doesn't handle
this yet.

Change-Id: I158dfa729315a9678a7fbb33ed465b73dfc9ec4b
diff --git a/gbproxy/GBProxy_Tests.ttcn b/gbproxy/GBProxy_Tests.ttcn
index ad95bff..dc5756c 100644
--- a/gbproxy/GBProxy_Tests.ttcn
+++ b/gbproxy/GBProxy_Tests.ttcn
@@ -2565,7 +2565,21 @@
 	f_cleanup();
 }
 
+/***********************************************************************
+ * MS-REGISTRATION ENQUIRY procedure
+ ***********************************************************************/
 
+private function f_TC_ms_reg_enq(charstring id) runs on BSSGP_ConnHdlr
+{
+	f_pcu2sgsn(ts_BSSGP_MS_REG_ENQ(g_pars.imsi), tr_BSSGP_MS_REG_ENQ(g_pars.imsi), use_sig := true);
+	f_sgsn2pcu(ts_BSSGP_MS_REW_ENQ_RESP(g_pars.imsi, omit), tr_BSSGP_MS_REW_ENQ_RESP(g_pars.imsi, omit), use_sig := true);
+}
+testcase TC_ms_reg_enq() runs on test_CT
+{
+	f_init();
+	f_start_handlers(refers(f_TC_ms_reg_enq), testcasename(), 22);
+	f_cleanup();
+}
 
 control {
 	execute( TC_BVC_bringup() );
@@ -2638,6 +2652,7 @@
 	execute( TC_flush_ll() );
 	execute( TC_fc_bvc() );
 	execute( TC_fc_ms() );
+	execute( TC_ms_reg_enq() );
 }