def test_add_already_added(self):
        prio_set_list = event._PrioritizedSetList()
        obj = object()
        prio_set_list.add(0, obj)

        with pytest.raises(ValueError) as excinfo:
            prio_set_list.add(0, obj)
        excinfo.match(r"has already been added")

        with pytest.raises(ValueError) as excinfo:
            prio_set_list.add(1, obj)
        excinfo.match(r"has already been added")
def get_snapshot_metadata(self, snapshot_id):
        """Get metadata of the snapshot."""
        url = "snapshots/%s/metadata" % str(snapshot_id)
        resp, body = self.get(url)
        body = json.loads(body)
        return resp, body['metadata']