AddrStruct implements the net.Addr for test purpose.
Network is part of net.Addr interface.
String is part of net.Addr interface.
FakeNetwork implements the NetworkInterfacer interface for test purpose.
NewFakeNetwork initializes a FakeNetwork.
AddInterfaceAddr create an interface and its associated addresses for FakeNetwork implementation.
Addrs is part of NetworkInterfacer interface.
Interfaces is part of NetworkInterfacer interface.