test-network: add a test case for DHCPv4.SendDecline=

test/test-network/conf/dhcp-client-decline.network

@@ -0,0 +1,9 @@
+[Match]
+Name=veth99
+
+[Network]
+DHCP=ipv4
+IPv6AcceptRA=false
+
+[DHCPv4]
+SendDecline=yes

test/test-network/conf/dhcp-server-decline.network

@@ -0,0 +1,14 @@
+[Match]
+Name=veth-peer
+
+[Network]
+Address=192.168.5.1/24
+Address=192.168.5.10/24
+IPv6AcceptRA=false
+DHCPServer=yes
+
+[DHCPServer]
+PoolOffset=10
+PoolSize=1
+DNS=192.168.5.1
+NTP=192.168.5.1

test/test-network/systemd-networkd-tests.py

@@ -2632,6 +2632,7 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
         '25-vrf.netdev',
         '25-vrf.network',
         'dhcp-client-anonymize.network',
+        'dhcp-client-decline.network',
         'dhcp-client-gateway-onlink-implicit.network',
         'dhcp-client-ipv4-dhcp-settings.network',
         'dhcp-client-ipv4-only-ipv6-disabled.network',
@@ -2656,6 +2657,7 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
         'dhcp-client-with-ipv4ll-fallback-without-dhcp-server.network',
         'dhcp-client-with-static-address.network',
         'dhcp-client.network',
+        'dhcp-server-decline.network',
         'dhcp-server-veth-peer.network',
         'dhcp-v4-server-veth-peer.network',
         'dhcp-client-use-domains.network',
@@ -3328,6 +3330,14 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
         print(output)
         self.assertRegex(output, 'example.com')
 
+    def test_dhcp_client_decline(self):
+        copy_unit_to_networkd_unit_path('25-veth.netdev', 'dhcp-server-decline.network', 'dhcp-client-decline.network')
+
+        start_networkd()
+        self.wait_online(['veth-peer:carrier'])
+        rc = call(*wait_online_cmd, '--timeout=10s', '--interface=veth99:routable', env=env)
+        self.assertTrue(rc == 1)
+
 class NetworkdIPv6PrefixTests(unittest.TestCase, Utilities):
     links = ['veth99']