selftests: ovpn: fail notification check on mismatch

compare_ntfs doesn't fail when expected and received notification
streams diverge.

Fix this bug by tracking the diff exit status explicitly and return it
to the caller so notification mismatches propagate as test failures.

Fixes: 77de28cd7c ("selftests: ovpn: add notification parsing and matching")
Signed-off-by: Ralf Lici <ralf@mandelbit.com>
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>

tools/testing/selftests/net/ovpn/common.sh

@@ -140,23 +140,35 @@ add_peer() {
 }
 
 compare_ntfs() {
+	local diff_rc=0
+	local diff_file
+
 	if [ ${#tmp_jsons[@]} -gt 0 ]; then
 		suffix=""
 		[ "${SYMMETRIC_ID}" -eq 1 ] && suffix="${suffix}-symm"
 		[ "$FLOAT" == 1 ] && suffix="${suffix}-float"
 		expected="json/peer${1}${suffix}.json"
 		received="${tmp_jsons[$1]}"
+		diff_file=$(mktemp)
 
 		kill -TERM ${listener_pids[$1]} || true
 		wait ${listener_pids[$1]} || true
 		printf "Checking notifications for peer ${1}... "
 		if diff <(jq -s "${JQ_FILTER}" ${expected}) \
-			<(jq -s "${JQ_FILTER}" ${received}); then
+			<(jq -s "${JQ_FILTER}" ${received}) \
+			>"${diff_file}" 2>&1; then
 			echo "OK"
+		else
+			diff_rc=$?
+			echo "failed"
+			cat "${diff_file}"
 		fi
 
+		rm -f "${diff_file}" || true
 		rm -f ${received} || true
 	fi
+
+	return "${diff_rc}"
 }
 
 cleanup() {