bsc: handover: actually send Handover Detect

Until now, the test went from RR Handover Command directly to RR Handover
Complete, and osmo-bsc didn't mind it. However, the normal handover procedure
requires an RSL Handover Detect to be sent in-between those. Send that.

Change-Id: I6e54edcc3a99e116d852eca8e48c7a5bc685e832

bsc/MSC_ConnectionHandler.ttcn

@@ -877,6 +877,10 @@ altstep as_handover(inout HandoverState st) runs on MSC_ConnHdlr {
 			 * before performing a hand-over */
 			f_rslem_resume(RSL1_PROC);
 
+			/* send handover detect */
+			RSL1.send(ts_RSL_HANDO_DET(new_chan_nr));
+			f_sleep(0.3);
+
 			/* send handover complete over the new channel */
 			var PDU_ML3_MS_NW l3_tx := valueof(ts_RRM_HandoverComplete('00'O));
 			RSL1.send(ts_RSL_DATA_IND(new_chan_nr, valueof(ts_RslLinkID_DCCH(0)),

library/RSL_Types.ttcn

@@ -1309,6 +1309,15 @@ template RSL_Message tr_RSL_MsgTypeDR(template RSL_MessageType msg_type) modifie
 		}
 	}
 
+	/* 8.4.7 BTS -> BSC */
+	template (value) RSL_Message ts_RSL_HANDO_DET(template (value) RslChannelNr chan_nr) := {
+		msg_disc := ts_RSL_MsgDisc(RSL_MDISC_DCHAN, false),
+		msg_type := RSL_MT_HANDO_DET,
+		ies := {
+			t_RSL_IE(RSL_IE_CHAN_NR, RSL_IE_Body:{chan_nr := chan_nr})
+		}
+	}
+
 
 	/* COMMON CHANNEL MANAGEMENT MESSAGES */