'Requires a replica set called "rs" on port 27017'

def test_replicaset_uri_passes_read_preference(self):

    try:
        conn = connect(db='mongoenginetest', host='mongodb://localhost/mongoenginetest?replicaSet=rs', read_preference=READ_PREF)
    except MongoEngineConnectionError as e:
        return
    if (not isinstance(conn, CONN_CLASS)):
        return
    self.assertEqual(conn.read_preference, READ_PREF)
