    @Test
    public void testLastBlockSeenHash() throws Exception {

        // Test the lastBlockSeenHash field works.

        // LastBlockSeenHash should be empty if never set.
        Wallet wallet = new Wallet(params);
        Protos.Wallet walletProto = new WalletProtobufSerializer().walletToProto(wallet);
        ByteString lastSeenBlockHash = walletProto.getLastSeenBlockHash();
        assertTrue(lastSeenBlockHash.isEmpty());

        // Create a block.
        Block block = new Block(params, BlockTest.blockBytes);
        Sha256Hash blockHash = block.getHash();
        wallet.setLastBlockSeenHash(blockHash);
        wallet.setLastBlockSeenHeight(1);

        // Roundtrip the wallet and check it has stored the blockHash.
        Wallet wallet1 = roundTrip(wallet);
        assertEquals(blockHash, wallet1.getLastBlockSeenHash());
        assertEquals(1, wallet1.getLastBlockSeenHeight());

        // Test the Satoshi genesis block (hash of all zeroes) is roundtripped ok.
        Block genesisBlock = MainNetParams.get().getGenesisBlock();
        wallet.setLastBlockSeenHash(genesisBlock.getHash());
        Wallet wallet2 = roundTrip(wallet);
        assertEquals(genesisBlock.getHash(), wallet2.getLastBlockSeenHash());
    }