grps: Add test for NS messages that shall be ignored

Several messages shall not be answered when a RESET hasn't been
received on a NS-VC:
- NS_RESET_ACK (see 3GPP TS 08.16, 7.3.1)
- NS_ALIVE_ACK (see 3GPP TS 08.16, 7.4.1)
- NS_STATUS (see 3GPP TS 08.16, 7.5.1)

Sponsored-by: On-Waves ehf
diff --git a/tests/gb/gprs_ns_test.ok b/tests/gb/gprs_ns_test.ok
index 8a61450..23c9e5f 100644
--- a/tests/gb/gprs_ns_test.ok
+++ b/tests/gb/gprs_ns_test.ok
@@ -85,6 +85,33 @@
 
 --- Process timers ---
 
+--- Send unexpected NS STATUS (should not be answered)---
+
+PROCESSING STATUS from 0x01020304:1111
+08 00 81 0a 02 81 0a 
+
+result (STATUS) = 0
+
+--- Send unexpected NS ALIVE ACK (should not be answered)---
+
+PROCESSING ALIVE_ACK from 0x01020304:1111
+0b 
+
+MESSAGE to BSS, msg length 7
+08 00 81 0a 02 81 0b 
+
+result (ALIVE_ACK) = 0
+
+--- Send unexpected NS RESET ACK (should not be answered)---
+
+PROCESSING RESET_ACK from 0x01020304:1111
+03 01 82 e0 01 04 82 e0 00 
+
+MESSAGE to BSS, msg length 15
+08 00 81 0a 02 89 03 01 82 e0 01 04 82 e0 00 
+
+result (RESET_ACK) = 0
+
 --- Setup, send BSSGP RESET ---
 
 Setup NS-VC: remote 0x01020304:1111, NSVCI 0x1122(4386), NSEI 0x1122(4386)