test.java

    @Before
    public void setupTest() throws IOException {
        indexNode = startMasterAndIndexNode();
        searchNodeWithStrategy = startSearchNode(repositoryStrategy);

        indexName = randomAlphaOfLength(10).toLowerCase(Locale.ROOT);

        XContentBuilder mapping = jsonBuilder().startObject().field("dynamic", true).endObject();

        assertAcked(indicesAdmin().prepareCreate(indexName).setMapping(mapping).setSettings(
            Settings.builder()
                .put(IndexMetadata.SETTING_NUMBER_OF_SHARDS, 1)
                .put(IndexMetadata.SETTING_NUMBER_OF_REPLICAS, 1)
        ));

        ensureGreen(indexName);
        searchNode = startSearchNode(printingRepositoryStrategy);
        ensureGreen();
        shardId = new ShardId(resolveIndex(indexName), 0);
    }

    @After
    public void teardownTest() {
        assertAcked(client().admin().indices().prepareDelete(indexName));
        indexNode = null;
        searchNodeWithStrategy = null;
        searchNode = null;
        indexName = null;
    }

    public void testRetainCommitForReadersAfterShardMovedAway() throws ExecutionException, InterruptedException {
        logger.info("~~~starting test");
        int docsToIndex = 50;

        var bulkRequest = client().prepareBulk();
        for (int i = 0; i < docsToIndex; i++) {
            bulkRequest.add(new IndexRequest(indexName).source("field", randomUnicodeOfCodepointLengthBetween(1, 25)));
        }
        var bulkResponse = bulkRequest.get();
        assertNoFailures(bulkResponse);

        prepareIndex("test").setId("1").setSource(XContentType.JSON, "field1", "value1").get();
        prepareIndex("test").setSource(XContentType.JSON, "message", "wanderlust", "field1", 4, "foo", 3, "bar", "turtles").get();
        prepareIndex("test").setSource(XContentType.JSON, "field3", "value3", "rutroh", "fifty", "gah", 50).get();

        indexDocs(indexName, scaledRandomIntBetween(10, 50));

        logger.info("~~~done writing, about to flush/refresh");

        flush(indexName);
        refresh(indexName);

        repositoryStrategy.setBlockReadsLatch();

        assertResponse(prepareSearch().setQuery(QueryBuilders.matchQuery("message", "wanderlust")), response -> {
            logger.info("~~~response1: " + response);
        });

        logger.info("~~~finished one query, starting the other");

        assertResponse(prepareSearch().setQuery(QueryBuilders.matchAllQuery()), response -> {
            logger.info("~~~response2: " + response);
        });

        logger.info("--> relocate replica shard from: {} to: {}", searchNodeWithStrategy, searchNode);
        clusterAdmin()
            .prepareReroute()
            .add(new MoveAllocationCommand(indexName, 0, searchNodeWithStrategy, searchNode))
            .execute()
            .actionGet()
            .getState();
        ensureGreen(indexName);

        logger.info("--> relocation finished");

        logger.info("~~~done flush/refresh");

        repositoryStrategy.releaseBlockReadsLatch();
        

        logger.info("~~~done reading");


    }