Incorporate PR review feedback

server/src/internalClusterTest/java/org/opensearch/remotestore/RemoteStoreBackpressureIT.java

@@ -34,49 +34,21 @@
 
 @OpenSearchIntegTestCase.ClusterScope(scope = OpenSearchIntegTestCase.Scope.TEST, numDataNodes = 0)
 public class RemoteStoreBackpressureIT extends AbstractRemoteStoreMockRepositoryIntegTestCase {
-
-    public void testWritesRejected() {
-        Path location = randomRepoPath().toAbsolutePath();
-        setup(location, 1d, "metadata", Long.MAX_VALUE);
-
-        Settings request = Settings.builder().put(REMOTE_REFRESH_SEGMENT_PRESSURE_ENABLED.getKey(), true).build();
-        ClusterUpdateSettingsResponse clusterUpdateResponse = client().admin()
-            .cluster()
-            .prepareUpdateSettings()
-            .setPersistentSettings(request)
-            .get();
-        assertEquals(clusterUpdateResponse.getPersistentSettings().get(REMOTE_REFRESH_SEGMENT_PRESSURE_ENABLED.getKey()), "true");
-
-        logger.info("--> Indexing data");
-        OpenSearchRejectedExecutionException ex = assertThrows(
-            OpenSearchRejectedExecutionException.class,
-            () -> indexData(randomIntBetween(10, 20), randomBoolean())
-        );
-        assertTrue(ex.getMessage().contains("rejected execution on primary shard"));
-        String shardId = "0";
-        RemoteStoreStatsResponse response = client().admin().cluster().prepareRemoteStoreStats(INDEX_NAME, shardId).get();
-        final String indexShardId = String.format(Locale.ROOT, "[%s][%s]", INDEX_NAME, shardId);
-        List<RemoteStoreStats> matches = Arrays.stream(response.getShards())
-            .filter(stat -> indexShardId.equals(stat.getStats().shardId.toString()))
-            .collect(Collectors.toList());
-        assertEquals(1, matches.size());
-        RemoteRefreshSegmentTracker.Stats stats = matches.get(0).getStats();
-        assertTrue(stats.bytesLag > 0);
-        assertTrue(stats.refreshTimeLagMs > 0);
-        assertTrue(stats.localRefreshNumber - stats.remoteRefreshNumber > 0);
-        assertTrue(stats.rejectionCount > 0);
-        deleteRepo();
-    }
-
     public void testWritesRejectedDueToConsecutiveFailureBreach() throws Exception {
+        // Here the doc size of the request remains same throughout the test. After initial indexing, all remote store interactions
+        // fail leading to consecutive failure limit getting exceeded and leading to rejections.
         validateBackpressure(ByteSizeUnit.KB.toIntBytes(1), 10, ByteSizeUnit.KB.toIntBytes(1), 15, "failure_streak_count");
     }
 
     public void testWritesRejectedDueToBytesLagBreach() throws Exception {
+        // Initially indexing happens with doc size of 2 bytes, then all remote store interactions start failing. Now, the
+        // indexing happens with doc size of 1KB leading to bytes lag limit getting exceeded and leading to rejections.
         validateBackpressure(ByteSizeUnit.BYTES.toIntBytes(2), 30, ByteSizeUnit.KB.toIntBytes(1), 15, "bytes_lag");
     }
 
     public void testWritesRejectedDueToTimeLagBreach() throws Exception {
+        // Initially indexing happens with doc size of 1KB, then all remote store interactions start failing. Now, the
+        // indexing happens with doc size of 1 byte leading to time lag limit getting exceeded and leading to rejections.
         validateBackpressure(ByteSizeUnit.KB.toIntBytes(1), 20, ByteSizeUnit.BYTES.toIntBytes(1), 15, "time_lag");
     }
 
@@ -135,6 +107,11 @@ private void validateBackpressure(
             assertEquals(0, finalStats.refreshTimeLagMs);
             assertEquals(0, finalStats.localRefreshNumber - finalStats.remoteRefreshNumber);
         }, 30, TimeUnit.SECONDS);
+
+        long rejectionCount = stats.rejectionCount;
+        stats = stats();
+        indexDocAndRefresh(initialSource, initialDocsToIndex);
+        assertEquals(rejectionCount, stats.rejectionCount);
         deleteRepo();
     }