@Test
  public void testFinalizedBlocks() throws Exception {
    final int UNDOABLE_BLOCKS_STORED = 10;
    store = createStore(params, UNDOABLE_BLOCKS_STORED);
    chain = new FullPrunedBlockChain(params, store);

    // Check that we aren't accidentally leaving any references
    // to the full StoredUndoableBlock's lying around (ie memory leaks)

    ECKey outKey = new ECKey();
    int height = 1;

    // Build some blocks on genesis block to create a spendable output
    Block rollingBlock =
        params
            .getGenesisBlock()
            .createNextBlockWithCoinbase(Block.BLOCK_VERSION_GENESIS, outKey.getPubKey(), height++);
    chain.add(rollingBlock);
    TransactionOutPoint spendableOutput =
        new TransactionOutPoint(params, 0, rollingBlock.getTransactions().get(0).getHash());
    byte[] spendableOutputScriptPubKey =
        rollingBlock.getTransactions().get(0).getOutputs().get(0).getScriptBytes();
    for (int i = 1; i < params.getSpendableCoinbaseDepth(); i++) {
      rollingBlock =
          rollingBlock.createNextBlockWithCoinbase(
              Block.BLOCK_VERSION_GENESIS, outKey.getPubKey(), height++);
      chain.add(rollingBlock);
    }

    WeakReference<UTXO> out =
        new WeakReference<UTXO>(
            store.getTransactionOutput(spendableOutput.getHash(), spendableOutput.getIndex()));
    rollingBlock = rollingBlock.createNextBlock(null);

    Transaction t = new Transaction(params);
    // Entirely invalid scriptPubKey
    t.addOutput(new TransactionOutput(params, t, FIFTY_COINS, new byte[] {}));
    t.addSignedInput(spendableOutput, new Script(spendableOutputScriptPubKey), outKey);
    rollingBlock.addTransaction(t);
    rollingBlock.solve();

    chain.add(rollingBlock);
    WeakReference<StoredUndoableBlock> undoBlock =
        new WeakReference<StoredUndoableBlock>(store.getUndoBlock(rollingBlock.getHash()));

    StoredUndoableBlock storedUndoableBlock = undoBlock.get();
    assertNotNull(storedUndoableBlock);
    assertNull(storedUndoableBlock.getTransactions());
    WeakReference<TransactionOutputChanges> changes =
        new WeakReference<TransactionOutputChanges>(storedUndoableBlock.getTxOutChanges());
    assertNotNull(changes.get());
    storedUndoableBlock = null; // Blank the reference so it can be GCd.

    // Create a chain longer than UNDOABLE_BLOCKS_STORED
    for (int i = 0; i < UNDOABLE_BLOCKS_STORED; i++) {
      rollingBlock = rollingBlock.createNextBlock(null);
      chain.add(rollingBlock);
    }
    // Try to get the garbage collector to run
    System.gc();
    assertNull(undoBlock.get());
    assertNull(changes.get());
    assertNull(out.get());
    try {
      store.close();
    } catch (Exception e) {
    }
  }