@VisibleForTesting
    public ResultStore getResultStore() {
        return resultStore;
    }
@Test
    void testFetchResultInParallel() throws Exception {
        ResultFetcher fetcher =
                buildResultFetcher(Collections.singletonList(data.iterator()), data.size() / 2);
        CommonTestUtils.waitUtil(
                () -> fetcher.getResultStore().getBufferedRecordSize() > 0,
                Duration.ofSeconds(10),
                "Failed to wait the buffer has data.");
        checkFetchResultInParallel(fetcher);
    }