//mockHostCollection
ResourceCollection<DhcpHost> hosts = new ResourceCollection<DhcpHost>(new ArrayList<DhcpHost>());
//mockDhcpSubnet
DhcpSubnet mockSub = mock(DhcpSubnet.class);
when(mockSub.addDhcpHost()).thenReturn(mockDhcpHost);
when(mockSub.getDhcpHosts()).thenReturn(hosts);
//mockSubnetCollection
ResourceCollection mockSubnetCollection = mock(ResourceCollection.class);
when(mockSubnetCollection.get(anyInt())).thenReturn(mockSub);