to do this, etcd should be installed first and a member should be registered to it and then be loaded into a service class. but using spec script it would be impossible to do that. so i have to make a fake service instance and then test get_endpoint.
i really doubt if that kind of spec test is helpful for Attributes library, most methods of which are strongly related to etcd. 
or do you think etcd should be installed and run in spec test?