test: exercise legacy VPN gateway IP fallback

Author: Dogface2k

server/src/test/java/com/cloud/network/vpn/Site2SiteVpnManagerImplTest.java

@@ -331,6 +331,7 @@ public void testCreateVpnGatewayNoSourceNatIp() {
         CreateVpnGatewayCmd cmd = mock(CreateVpnGatewayCmd.class);
         when(cmd.getVpcId()).thenReturn(VPC_ID);
         when(cmd.getEntityOwnerId()).thenReturn(ACCOUNT_ID);
+        when(cmd.getIpAddressId()).thenReturn(null);
 
         when(_vpcDao.findById(VPC_ID)).thenReturn(vpc);
         when(_vpnGatewayDao.findByVpcId(VPC_ID)).thenReturn(null);
@@ -340,6 +341,46 @@ public void testCreateVpnGatewayNoSourceNatIp() {
         site2SiteVpnManager.createVpnGateway(cmd);
     }
 
+    @Test
+    public void testCreateVpnGatewaySkipsSystemVmSourceNatIp() {
+        CreateVpnGatewayCmd cmd = mock(CreateVpnGatewayCmd.class);
+        when(cmd.getVpcId()).thenReturn(VPC_ID);
+        when(cmd.getEntityOwnerId()).thenReturn(ACCOUNT_ID);
+        when(cmd.getIpAddressId()).thenReturn(null);
+        when(cmd.isDisplay()).thenReturn(true);
+        IPAddressVO systemVmIp = mock(IPAddressVO.class);
+        when(systemVmIp.isForSystemVms()).thenReturn(true);
+        when(_vpcDao.findById(VPC_ID)).thenReturn(vpc);
+        when(_vpnGatewayDao.findByVpcId(VPC_ID)).thenReturn(null);
+        mockVpcVirtualRouterProvider();
+        when(_ipAddressDao.listByAssociatedVpc(VPC_ID, true)).thenReturn(List.of(systemVmIp, ipAddress));
+        when(_vpnGatewayDao.persist(any(Site2SiteVpnGatewayVO.class))).thenReturn(vpnGateway);
+
+        Site2SiteVpnGateway result = site2SiteVpnManager.createVpnGateway(cmd);
+
+        assertNotNull(result);
+        ArgumentCaptor<Site2SiteVpnGatewayVO> gatewayCaptor = ArgumentCaptor.forClass(Site2SiteVpnGatewayVO.class);
+        verify(_vpnGatewayDao).persist(gatewayCaptor.capture());
+        assertEquals(IP_ADDRESS_ID.longValue(), gatewayCaptor.getValue().getAddrId());
+    }
+
+    @Test(expected = CloudRuntimeException.class)
+    public void testCreateVpnGatewayRejectsMultipleCustomerSourceNatIps() {
+        CreateVpnGatewayCmd cmd = mock(CreateVpnGatewayCmd.class);
+        when(cmd.getVpcId()).thenReturn(VPC_ID);
+        when(cmd.getEntityOwnerId()).thenReturn(ACCOUNT_ID);
+        when(cmd.getIpAddressId()).thenReturn(null);
+        IPAddressVO secondIp = mock(IPAddressVO.class);
+        when(ipAddress.getAddress()).thenReturn(new Ip("203.0.113.34"));
+        when(secondIp.getAddress()).thenReturn(new Ip("203.0.113.35"));
+        when(_vpcDao.findById(VPC_ID)).thenReturn(vpc);
+        when(_vpnGatewayDao.findByVpcId(VPC_ID)).thenReturn(null);
+        mockVpcVirtualRouterProvider();
+        when(_ipAddressDao.listByAssociatedVpc(VPC_ID, true)).thenReturn(List.of(ipAddress, secondIp));
+
+        site2SiteVpnManager.createVpnGateway(cmd);
+    }
+
     @Test(expected = InvalidParameterValueException.class)
     public void testCreateCustomerGatewayInvalidIp() {
         CreateVpnCustomerGatewayCmd cmd = mock(CreateVpnCustomerGatewayCmd.class);