@Test
  public void testStatsManagerDeleteTombstoneStats() {
    List<PartitionId> unreachablePartitions = Collections.emptyList();
    Map<Long, Map<Short, Map<Short, ContainerStorageStats>>> hostAccountStorageStatsMap = new HashMap<>();
    for (PartitionId partitionId : storeMap.keySet()) {
      statsManager.collectAndAggregateAccountStorageStats(hostAccountStorageStatsMap, partitionId,
          unreachablePartitions);
    }

    // verify aggregated delete tombstone stats
    DeleteTombstoneStats deleteTombstoneStats = statsManager.getAggregatedDeleteTombstoneStats();
    assertEquals("Mismatch in expired delete count", storeMap.size() * storeDeleteTombstoneStats.expiredCount,
        deleteTombstoneStats.expiredCount);
    assertEquals("Mismatch in expired delete size", storeMap.size() * storeDeleteTombstoneStats.expiredSize,
        deleteTombstoneStats.expiredSize);
    assertEquals("Mismatch in permanent delete count", storeMap.size() * storeDeleteTombstoneStats.permanentCount,
        deleteTombstoneStats.permanentCount);
    assertEquals("Mismatch in permanent delete size", storeMap.size() * storeDeleteTombstoneStats.permanentSize,
        deleteTombstoneStats.permanentSize);
  }
Test to verify that the {@link StatsManager} is collecting delete tombstone stats.
ambry-server/src/test/java/com/github/ambry/server/StatsManagerTest.java