def METHOD_NAME(self):
    store = self.get_store(batch_size=50, serialization_format="firehose_v1")
    store.configured = True
    mock_client = Mock()
    mock_client.put_records.return_value = {
        "FailedRecordCount": 1,
        "Records": [
            {}, {"SequenceNumber": 1, "ShardId": 2}
        ]
    }
    store.client = mock_client
    event1 = self.build_login_event()
    event2 = self.build_login_event()
    self.assertEqual(
        list(store.bulk_store([event1, event2])),
        [(str(event2.metadata.uuid), event2.metadata.index)]
    )