func NewPeerRelation(c *gc.C, st *state.State) *PeerRelation {
svc := state.AddTestingService(c, st, "riak", state.AddTestingCharm(c, st, "riak"))
ep, err := svc.Endpoint("ring")
c.Assert(err, gc.IsNil)
rel, err := st.EndpointsRelation(ep)
c.Assert(err, gc.IsNil)
pr := &PeerRelation{rel: rel, svc: svc}
pr.u0, pr.ru0 = addRU(c, svc, rel, nil)
pr.u1, pr.ru1 = addRU(c, svc, rel, nil)
pr.u2, pr.ru2 = addRU(c, svc, rel, nil)
pr.u3, pr.ru3 = addRU(c, svc, rel, nil)
return pr
}