selftests: fib_tests: add more tests for metric update

This patch adds two more tests to ipv4_addr_metric_test() to
explicitly cover the scenarios fixed by the previous patch.

Suggested-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/fib_tests.sh

@@ -1438,6 +1438,27 @@ ipv4_addr_metric_test()
 	fi
 	log_test $rc 0 "Prefix route with metric on link up"
 
+	# explicitly check for metric changes on edge scenarios
+	run_cmd "$IP addr flush dev dummy2"
+	run_cmd "$IP addr add dev dummy2 172.16.104.0/24 metric 259"
+	run_cmd "$IP addr change dev dummy2 172.16.104.0/24 metric 260"
+	rc=$?
+	if [ $rc -eq 0 ]; then
+		check_route "172.16.104.0/24 dev dummy2 proto kernel scope link src 172.16.104.0 metric 260"
+		rc=$?
+	fi
+	log_test $rc 0 "Modify metric of .0/24 address"
+
+	run_cmd "$IP addr flush dev dummy2"
+	run_cmd "$IP addr add dev dummy2 172.16.104.1/32 peer 172.16.104.2 metric 260"
+	run_cmd "$IP addr change dev dummy2 172.16.104.1/32 peer 172.16.104.2 metric 261"
+	rc=$?
+	if [ $rc -eq 0 ]; then
+		check_route "172.16.104.2 dev dummy2 proto kernel scope link src 172.16.104.1 metric 261"
+		rc=$?
+	fi
+	log_test $rc 0 "Modify metric of address with peer route"
+
 	$IP li del dummy1
 	$IP li del dummy2
 	cleanup