test: Add a ussd test for an issue seen at the 30C3

I don't have all the details from the 30C3 in mind anymore but
the interrogateSS lead to phones being un-happy.

ussd/USSDTest.st

@@ -0,0 +1,76 @@
+"
+ (C) 2012 by Holger Hans Peter Freyther
+ All Rights Reserved
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU Affero General Public License as
+ published by the Free Software Foundation, either version 3 of the
+ License, or (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ GNU Affero General Public License for more details.
+
+ You should have received a copy of the GNU Affero General Public License
+ along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"
+
+PackageLoader fileInPackage: #FakeBTS.
+
+FakeBTS.OpenBSCTest subclass: USSDTest [
+    <import: OsmoGSM>
+
+    USSDTest class >> registerMessage [
+        ^#[16r1B 16r3B 16r1C 16r15 16rA1 16r13 16r02
+           16r01 16r04 16r02 16r01 16r3B 16r30 16r0B
+           16r04 16r01 16r0F 16r04 16r06 16rAA 16r51
+           16r0C 16r06 16r1B 16r01 16r7F 16r01 16r00]
+    ]
+
+    USSDTest class >> interrogateSS [
+	^#[16r1B 16r7B 16r1C 16r0D 16rA1 16r0B 16r02
+	   16r01 16r01 16r02 16r01 16r0E 16r30 16r03
+	   16r04 16r01 16r11 16r7F 16r01 16r00]
+    ]
+
+    startTest [
+        "1. Connect to the BTS"
+"        bts := self createBTS.
+        bts btsId: '106/0/0'.
+        bts connect: '192.168.46.1'.
+        bts waitForBTSReady."
+        self createAndConnectBTS: '1234/0/0'.
+
+        self
+            testUSSDMessage
+    ]
+
+    testUSSDMessage [
+        | tmsi cm lchan |
+
+        tmsi := self allocateTmsi: '901010000001111'.
+
+        "2. Get a LCHAN"
+        lchan := self requireAnyChannel.
+
+        "3. Send a CM Service Request "
+        cm := GSM48CMServiceReq new.
+        cm mi tmsi: tmsi.
+        lchan sendGSM: cm toMessage.
+
+	"4. USSD messages"
+	lchan sendGSM: self class interrogateSS sapi: 3.
+
+        stdin next.
+    ]
+]
+
+Eval [
+    | test |
+
+    test := USSDTest new
+                startTest;
+                stopBts;
+                yourself.
+]