### Question:
ClientBackedDataStore extends AbstractDataStore { @Override public DOMStoreTransactionChain createTransactionChain() { return new ClientBackedTransactionChain(getClient().createLocalHistory(), debugAllocation()); } ClientBackedDataStore(final ActorSystem actorSystem, final ClusterWrapper cluster,
            final Configuration configuration, final DatastoreContextFactory datastoreContextFactory,
            final DatastoreSnapshot restoreFromSnapshot); @VisibleForTesting  ClientBackedDataStore(final ActorUtils actorUtils, final ClientIdentifier identifier,
                          final DataStoreClient clientActor); @Override DOMStoreTransactionChain createTransactionChain(); @Override DOMStoreReadTransaction newReadOnlyTransaction(); @Override DOMStoreWriteTransaction newWriteOnlyTransaction(); @Override DOMStoreReadWriteTransaction newReadWriteTransaction();  }### Answer:
@Test public void testCreateTransactionChain() { try (ClientBackedDataStore clientBackedDataStore = new ClientBackedDataStore( actorUtils, UNKNOWN_ID, clientActor)) { final DOMStoreTransactionChain txChain = clientBackedDataStore.createTransactionChain(); assertNotNull(txChain); verify(clientActor, Mockito.times(1)).createLocalHistory(); } }