### Question:
ReconOmMetadataManagerImpl extends OmMetadataManagerImpl implements ReconOMMetadataManager { @Override public void start(OzoneConfiguration configuration) throws IOException { LOG.info("Starting ReconOMMetadataManagerImpl"); File reconDbDir = reconUtils.getReconDbDir(configuration, OZONE_RECON_OM_SNAPSHOT_DB_DIR); File lastKnownOMSnapshot = reconUtils.getLastKnownDB(reconDbDir, RECON_OM_SNAPSHOT_DB); if (lastKnownOMSnapshot != null) { LOG.info("Last known snapshot for OM : {}", lastKnownOMSnapshot.getAbsolutePath()); initializeNewRdbStore(lastKnownOMSnapshot); } } @Inject  ReconOmMetadataManagerImpl(OzoneConfiguration configuration,
                                    ReconUtils reconUtils); @Override void start(OzoneConfiguration configuration); @Override void updateOmDB(File newDbLocation); @Override long getLastSequenceNumberFromDB(); @Override boolean isOmTablesInitialized();  }### Answer:
@Test public void testStart() throws Exception { OMMetadataManager omMetadataManager = getOMMetadataManager(); DBCheckpoint checkpoint = omMetadataManager.getStore() .getCheckpoint(true); File snapshotFile = new File( checkpoint.getCheckpointLocation().getParent() + "/" + "om.snapshot.db_" + System.currentTimeMillis()); checkpoint.getCheckpointLocation().toFile().renameTo(snapshotFile); File reconOmDbDir = temporaryFolder.newFolder(); OzoneConfiguration configuration = new OzoneConfiguration(); configuration.set(OZONE_RECON_OM_SNAPSHOT_DB_DIR, reconOmDbDir .getAbsolutePath()); FileUtils.copyDirectory(snapshotFile.getParentFile(), reconOmDbDir); ReconOMMetadataManager reconOMMetadataManager = new ReconOmMetadataManagerImpl(configuration, new ReconUtils()); reconOMMetadataManager.start(configuration); Assert.assertNotNull(reconOMMetadataManager.getBucketTable()); Assert.assertNotNull(reconOMMetadataManager.getVolumeTable() .get("/sampleVol")); Assert.assertNotNull(reconOMMetadataManager.getBucketTable() .get("/sampleVol/bucketOne")); Assert.assertNotNull(reconOMMetadataManager.getKeyTable() .get("/sampleVol/bucketOne/key_one")); Assert.assertNotNull(reconOMMetadataManager.getKeyTable() .get("/sampleVol/bucketOne/key_two")); }