dash/test/functional/wallet_basic.py

#!/usr/bin/env python3
# Copyright (c) 2014-2019 The Bitcoin Core developers
# Distributed under the MIT software license, see the accompanying
# file COPYING or http://www.opensource.org/licenses/mit-license.php.
"""Test the wallet."""
from decimal import Decimal
import time

from test_framework.test_framework import BitcoinTestFramework
from test_framework.util import (
    assert_array_result,
    assert_equal,
    assert_fee_amount,
    assert_raises_rpc_error,
    connect_nodes,
    count_bytes,
    wait_until,
)


class WalletTest(BitcoinTestFramework):
    def set_test_params(self):
        self.num_nodes = 4
        self.setup_clean_chain = True
        self.extra_args = [['-usehd={:d}'.format(i%2==0)] for i in range(4)]

    def skip_test_if_missing_module(self):
        self.skip_if_no_wallet()

    def setup_network(self):
        self.add_nodes(4, self.extra_args)
        self.start_node(0)
        self.start_node(1)
        self.start_node(2)
        connect_nodes(self.nodes[0], 1)
        connect_nodes(self.nodes[1], 2)
        connect_nodes(self.nodes[0], 2)
        self.sync_all(self.nodes[0:3])

    def check_fee_amount(self, curr_balance, balance_with_fee, fee_per_byte, tx_size):
        """Return curr_balance after asserting the fee was in range"""
        fee = balance_with_fee - curr_balance
        assert_fee_amount(fee, tx_size, fee_per_byte * 1000)
        return curr_balance

    def run_test(self):
        # Check that there's no UTXO on none of the nodes
        assert_equal(len(self.nodes[0].listunspent()), 0)
        assert_equal(len(self.nodes[1].listunspent()), 0)
        assert_equal(len(self.nodes[2].listunspent()), 0)

        self.log.info("Mining blocks...")

        self.nodes[0].generate(1)

        walletinfo = self.nodes[0].getwalletinfo()
        assert_equal(walletinfo['immature_balance'], 500)
        assert_equal(walletinfo['balance'], 0)

        self.sync_all(self.nodes[0:3])
        self.nodes[1].generate(101)
        self.sync_all(self.nodes[0:3])

        assert_equal(self.nodes[0].getbalance(), 500)
        assert_equal(self.nodes[1].getbalance(), 500)
        assert_equal(self.nodes[2].getbalance(), 0)

        # Check that only first and second nodes have UTXOs
        utxos = self.nodes[0].listunspent()
        assert_equal(len(utxos), 1)
        assert_equal(len(self.nodes[1].listunspent()), 1)
        assert_equal(len(self.nodes[2].listunspent()), 0)

        self.log.info("test gettxout")
        confirmed_txid, confirmed_index = utxos[0]["txid"], utxos[0]["vout"]
        # First, outputs that are unspent both in the chain and in the
        # mempool should appear with or without include_mempool
        txout = self.nodes[0].gettxout(txid=confirmed_txid, n=confirmed_index, include_mempool=False)
        assert_equal(txout['value'], 500)
        txout = self.nodes[0].gettxout(txid=confirmed_txid, n=confirmed_index, include_mempool=True)
        assert_equal(txout['value'], 500)

        # Send 210 DASH from 0 to 2 using sendtoaddress call.
        # Second transaction will be child of first, and will require a fee
        self.nodes[0].sendtoaddress(self.nodes[2].getnewaddress(), 110)
        mempool_txid = self.nodes[0].sendtoaddress(self.nodes[2].getnewaddress(), 100)

        self.log.info("test gettxout (second part)")
        # utxo spent in mempool should be visible if you exclude mempool
        # but invisible if you include mempool
        txout = self.nodes[0].gettxout(confirmed_txid, confirmed_index, False)
        assert_equal(txout['value'], 500)
        txout = self.nodes[0].gettxout(confirmed_txid, confirmed_index, True)
        assert txout is None
        # new utxo from mempool should be invisible if you exclude mempool
        # but visible if you include mempool
        txout = self.nodes[0].gettxout(mempool_txid, 0, False)
        assert txout is None
        txout1 = self.nodes[0].gettxout(mempool_txid, 0, True)
        txout2 = self.nodes[0].gettxout(mempool_txid, 1, True)
        # note the mempool tx will have randomly assigned indices
        # but 10 will go to node2 and the rest will go to node0
        balance = self.nodes[0].getbalance()
        assert_equal(set([txout1['value'], txout2['value']]), set([100, balance]))

        walletinfo = self.nodes[0].getwalletinfo()
        assert_equal(walletinfo['immature_balance'], 0)

        # Have node0 mine a block, thus it will collect its own fee.
        self.nodes[0].generate(1)
        self.sync_all(self.nodes[0:3])

        # Exercise locking of unspent outputs
        unspent_0 = self.nodes[2].listunspent()[0]
        unspent_0 = {"txid": unspent_0["txid"], "vout": unspent_0["vout"]}
        assert_raises_rpc_error(-8, "Invalid parameter, expected locked output", self.nodes[2].lockunspent, True, [unspent_0])
        self.nodes[2].lockunspent(False, [unspent_0])
        assert_raises_rpc_error(-8, "Invalid parameter, output already locked", self.nodes[2].lockunspent, False, [unspent_0])
        assert_raises_rpc_error(-4, "Insufficient funds", self.nodes[2].sendtoaddress, self.nodes[2].getnewaddress(), 200)
        assert_equal([unspent_0], self.nodes[2].listlockunspent())
        self.nodes[2].lockunspent(True, [unspent_0])
        assert_equal(len(self.nodes[2].listlockunspent()), 0)
        assert_raises_rpc_error(-8, "Invalid parameter, unknown transaction",
                                self.nodes[2].lockunspent, False,
                                [{"txid": "0000000000000000000000000000000000", "vout": 0}])
        assert_raises_rpc_error(-8, "Invalid parameter, vout index out of bounds",
                                self.nodes[2].lockunspent, False,
                                [{"txid": unspent_0["txid"], "vout": 999}])

        # An output should be unlocked when spent
        unspent_0 = self.nodes[1].listunspent()[0]
        self.nodes[1].lockunspent(False, [unspent_0])
        tx = self.nodes[1].createrawtransaction([unspent_0], { self.nodes[1].getnewaddress() : 1 })
        tx = self.nodes[1].fundrawtransaction(tx)['hex']
        tx = self.nodes[1].signrawtransactionwithwallet(tx)["hex"]
        self.nodes[1].sendrawtransaction(tx)
        assert_equal(len(self.nodes[1].listlockunspent()), 0)

        # Have node1 generate 100 blocks (so node0 can recover the fee)
        self.nodes[1].generate(100)
        self.sync_all(self.nodes[0:3])

        # node0 should end up with 1000 DASH in block rewards plus fees, but
        # minus the 210 plus fees sent to node2
        assert_equal(self.nodes[0].getbalance(), 1000 - 210)
        assert_equal(self.nodes[2].getbalance(), 210)

        # Node0 should have two unspent outputs.
        # Create a couple of transactions to send them to node2, submit them through
        # node1, and make sure both node0 and node2 pick them up properly:
        node0utxos = self.nodes[0].listunspent(1)
        assert_equal(len(node0utxos), 2)

        fee_per_input = Decimal('0.00001')
        totalfee = 0
        # create both transactions
        txns_to_send = []
        for utxo in node0utxos:
            inputs = []
            outputs = {}
            inputs.append({"txid": utxo["txid"], "vout": utxo["vout"]})
            outputs[self.nodes[2].getnewaddress()] = utxo["amount"] - fee_per_input
            raw_tx = self.nodes[0].createrawtransaction(inputs, outputs)
            txns_to_send.append(self.nodes[0].signrawtransactionwithwallet(raw_tx))
            totalfee += fee_per_input

        # Have node 1 (miner) send the transactions
        self.nodes[1].sendrawtransaction(txns_to_send[0]["hex"], 0)
        self.nodes[1].sendrawtransaction(txns_to_send[1]["hex"], 0)

        # Have node1 mine a block to confirm transactions:
        self.nodes[1].generate(1)
        self.sync_all(self.nodes[0:3])

        assert_equal(self.nodes[0].getbalance(), 0)
        assert_equal(self.nodes[2].getbalance(), 1000 - totalfee)

        # Verify that a spent output cannot be locked anymore
        spent_0 = {"txid": node0utxos[0]["txid"], "vout": node0utxos[0]["vout"]}
        assert_raises_rpc_error(-8, "Invalid parameter, expected unspent output", self.nodes[0].lockunspent, False, [spent_0])

        # Send 100 DASH normal
        address = self.nodes[0].getnewaddress("test")
        fee_per_byte = Decimal('0.00001') / 1000
        self.nodes[2].settxfee(fee_per_byte * 1000)
        txid = self.nodes[2].sendtoaddress(address, 100, "", "", False)
        self.nodes[2].generate(1)
        self.sync_all(self.nodes[0:3])
        node_2_bal = self.check_fee_amount(self.nodes[2].getbalance(), Decimal('900') - totalfee, fee_per_byte, count_bytes(self.nodes[2].gettransaction(txid)['hex']))
        assert_equal(self.nodes[0].getbalance(), Decimal('100'))

        # Send 100 DASH with subtract fee from amount
        txid = self.nodes[2].sendtoaddress(address, 100, "", "", True)
        self.nodes[2].generate(1)
        self.sync_all(self.nodes[0:3])
        node_2_bal -= Decimal('100')
        assert_equal(self.nodes[2].getbalance(), node_2_bal)
        node_0_bal = self.check_fee_amount(self.nodes[0].getbalance(), Decimal('200'), fee_per_byte, count_bytes(self.nodes[2].gettransaction(txid)['hex']))

        # Sendmany 100 DASH
        txid = self.nodes[2].sendmany('', {address: 100}, 0, False, "", [])
        self.nodes[2].generate(1)
        self.sync_all(self.nodes[0:3])
        node_0_bal += Decimal('100')
        node_2_bal = self.check_fee_amount(self.nodes[2].getbalance(), node_2_bal - Decimal('100'), fee_per_byte, count_bytes(self.nodes[2].gettransaction(txid)['hex']))
        assert_equal(self.nodes[0].getbalance(), node_0_bal)

        # Sendmany 100 DASH with subtract fee from amount
        txid = self.nodes[2].sendmany('', {address: 100}, 0, False, "", [address])
        self.nodes[2].generate(1)
        self.sync_all(self.nodes[0:3])
        node_2_bal -= Decimal('100')
        assert_equal(self.nodes[2].getbalance(), node_2_bal)
        node_0_bal = self.check_fee_amount(self.nodes[0].getbalance(), node_0_bal + Decimal('100'), fee_per_byte, count_bytes(self.nodes[2].gettransaction(txid)['hex']))

        self.start_node(3)
        connect_nodes(self.nodes[0], 3)
        self.sync_all()

        # check if we can list zero value tx as available coins
        # 1. create raw_tx
        # 2. hex-changed one output to 0.0
        # 3. sign and send
        # 4. check if recipient (node0) can list the zero value tx
        usp = self.nodes[1].listunspent(query_options={'minimumAmount': '499.998'})[0]
        inputs = [{"txid": usp['txid'], "vout": usp['vout']}]
        outputs = {self.nodes[1].getnewaddress(): 499.998, self.nodes[0].getnewaddress(): 11.11}

        raw_tx = self.nodes[1].createrawtransaction(inputs, outputs).replace("c0833842", "00000000")  # replace 11.11 with 0.0 (int32)
        signed_raw_tx = self.nodes[1].signrawtransactionwithwallet(raw_tx)
        decoded_raw_tx = self.nodes[1].decoderawtransaction(signed_raw_tx['hex'])
        zero_value_txid = decoded_raw_tx['txid']
        self.nodes[1].sendrawtransaction(signed_raw_tx['hex'])

        self.sync_all()
        self.nodes[1].generate(1)  # mine a block
        self.sync_all()

        unspent_txs = self.nodes[0].listunspent()  # zero value tx must be in listunspents output
        found = False
        for uTx in unspent_txs:
            if uTx['txid'] == zero_value_txid:
                found = True
                assert_equal(uTx['amount'], Decimal('0'))
        assert found

        # do some -walletbroadcast tests
        self.stop_nodes()
        self.start_node(0, ["-walletbroadcast=0"])
        self.start_node(1, ["-walletbroadcast=0"])
        self.start_node(2, ["-walletbroadcast=0"])
        connect_nodes(self.nodes[0], 1)
        connect_nodes(self.nodes[1], 2)
        connect_nodes(self.nodes[0], 2)
        self.sync_all(self.nodes[0:3])

        txid_not_broadcast = self.nodes[0].sendtoaddress(self.nodes[2].getnewaddress(), 2)
        tx_obj_not_broadcast = self.nodes[0].gettransaction(txid_not_broadcast)
        self.nodes[1].generate(1)  # mine a block, tx should not be in there
        self.sync_all(self.nodes[0:3])
        assert_equal(self.nodes[2].getbalance(), node_2_bal)  # should not be changed because tx was not broadcasted

        # now broadcast from another node, mine a block, sync, and check the balance
        self.nodes[1].sendrawtransaction(tx_obj_not_broadcast['hex'])
        self.nodes[1].generate(1)
        self.sync_all(self.nodes[0:3])
        node_2_bal += 2
        tx_obj_not_broadcast = self.nodes[0].gettransaction(txid_not_broadcast)
        assert_equal(self.nodes[2].getbalance(), node_2_bal)

        # create another tx
        self.nodes[0].sendtoaddress(self.nodes[2].getnewaddress(), 2)

        # restart the nodes with -walletbroadcast=1
        self.stop_nodes()
        self.start_node(0)
        self.start_node(1)
        self.start_node(2)
        connect_nodes(self.nodes[0], 1)
        connect_nodes(self.nodes[1], 2)
        connect_nodes(self.nodes[0], 2)
        self.sync_blocks(self.nodes[0:3])

        self.nodes[0].generate(1)
        self.sync_blocks(self.nodes[0:3])
        node_2_bal += 2

        # tx should be added to balance because after restarting the nodes tx should be broadcast
        assert_equal(self.nodes[2].getbalance(), node_2_bal)

        # send a tx with value in a string (PR#6380 +)
        txid = self.nodes[0].sendtoaddress(self.nodes[2].getnewaddress(), "2")
        tx_obj = self.nodes[0].gettransaction(txid)
        assert_equal(tx_obj['amount'], Decimal('-2'))

        txid = self.nodes[0].sendtoaddress(self.nodes[2].getnewaddress(), "0.0001")
        tx_obj = self.nodes[0].gettransaction(txid)
        assert_equal(tx_obj['amount'], Decimal('-0.0001'))

        # check if JSON parser can handle scientific notation in strings
        txid = self.nodes[0].sendtoaddress(self.nodes[2].getnewaddress(), "1e-4")
        tx_obj = self.nodes[0].gettransaction(txid)
        assert_equal(tx_obj['amount'], Decimal('-0.0001'))

        # General checks for errors from incorrect inputs
        # This will raise an exception because the amount type is wrong
        assert_raises_rpc_error(-3, "Invalid amount", self.nodes[0].sendtoaddress, self.nodes[2].getnewaddress(), "1f-4")

        # This will raise an exception since generate does not accept a string
        assert_raises_rpc_error(-1, "not an integer", self.nodes[0].generate, "2")

        # This will raise an exception for the invalid private key format
        assert_raises_rpc_error(-5, "Invalid private key encoding", self.nodes[0].importprivkey, "invalid")

        # This will raise an exception for importing an address with the PS2H flag
        temp_address = self.nodes[1].getnewaddress()
        assert_raises_rpc_error(-5, "Cannot use the p2sh flag with an address - use a script instead", self.nodes[0].importaddress, temp_address, "label", False, True)

        # This will raise an exception for attempting to dump the private key of an address you do not own
        assert_raises_rpc_error(-4, "Private key for address %s is not known" % temp_address, self.nodes[0].dumpprivkey, temp_address)

        # This will raise an exception for attempting to get the private key of an invalid Dash address
        assert_raises_rpc_error(-5, "Invalid Dash address", self.nodes[0].dumpprivkey, "invalid")

        # This will raise an exception for attempting to set a label for an invalid Dash address
        assert_raises_rpc_error(-5, "Invalid Dash address", self.nodes[0].setlabel, "invalid address", "label")

        # This will raise an exception for importing an invalid address
        assert_raises_rpc_error(-5, "Invalid Dash address or script", self.nodes[0].importaddress, "invalid")

        # This will raise an exception for attempting to import a pubkey that isn't in hex
        assert_raises_rpc_error(-5, "Pubkey must be a hex string", self.nodes[0].importpubkey, "not hex")

        # This will raise an exception for importing an invalid pubkey
        assert_raises_rpc_error(-5, "Pubkey is not a valid public key", self.nodes[0].importpubkey, "5361746f736869204e616b616d6f746f")

        # Import address and private key to check correct behavior of spendable unspents
        # 1. Send some coins to generate new UTXO
        address_to_import = self.nodes[2].getnewaddress()
        txid = self.nodes[0].sendtoaddress(address_to_import, 1)
        self.nodes[0].generate(1)
        self.sync_all(self.nodes[0:3])

        # 2. Import address from node2 to node1
        self.nodes[1].importaddress(address_to_import)

        # 3. Validate that the imported address is watch-only on node1
        assert self.nodes[1].getaddressinfo(address_to_import)["iswatchonly"]

        # 4. Check that the unspents after import are not spendable
        assert_array_result(self.nodes[1].listunspent(),
                            {"address": address_to_import},
                            {"spendable": False})

        # 5. Import private key of the previously imported address on node1
        priv_key = self.nodes[2].dumpprivkey(address_to_import)
        self.nodes[1].importprivkey(priv_key)

        # 6. Check that the unspents are now spendable on node1
        assert_array_result(self.nodes[1].listunspent(),
                            {"address": address_to_import},
                            {"spendable": True})

        # Mine a block from node0 to an address from node1
        coinbase_addr = self.nodes[1].getnewaddress()
        block_hash = self.nodes[0].generatetoaddress(1, coinbase_addr)[0]
        coinbase_txid = self.nodes[0].getblock(block_hash)['tx'][0]
        self.sync_all(self.nodes[0:3])

        # Check that the txid and balance is found by node1
        self.nodes[1].gettransaction(coinbase_txid)

        # check if wallet or blockchain maintenance changes the balance
        self.sync_all(self.nodes[0:3])
        blocks = self.nodes[0].generate(2)
        self.sync_all(self.nodes[0:3])
        balance_nodes = [self.nodes[i].getbalance() for i in range(3)]
        block_count = self.nodes[0].getblockcount()

        # Check modes:
        #   - True: unicode escaped as \u....
        #   - False: unicode directly as UTF-8
        for mode in [True, False]:
            self.nodes[0].rpc.ensure_ascii = mode
            # unicode check: Basic Multilingual Plane, Supplementary Plane respectively
            for label in [u'рыба', u'𝅘𝅥𝅯']:
                addr = self.nodes[0].getnewaddress()
                self.nodes[0].setlabel(addr, label)
                assert_equal(self.nodes[0].getaddressinfo(addr)['label'], label)
                assert label in self.nodes[0].listlabels()
        self.nodes[0].rpc.ensure_ascii = True  # restore to default

        # maintenance tests
        maintenance = [
            '-rescan',
            '-reindex',
            '-zapwallettxes=1',
            '-zapwallettxes=2',
            # disabled until issue is fixed: https://github.com/bitcoin/bitcoin/issues/7463
            # '-salvagewallet',
        ]
        chainlimit = 6
        for m in maintenance:
            self.log.info("check " + m)
            self.stop_nodes()
            # set lower ancestor limit for later
            self.start_node(0, [m, "-limitancestorcount=" + str(chainlimit)])
            self.start_node(1, [m, "-limitancestorcount=" + str(chainlimit)])
            self.start_node(2, [m, "-limitancestorcount=" + str(chainlimit)])
            if m == '-reindex':
                # reindex will leave rpc warm up "early"; Wait for it to finish
                wait_until(lambda: [block_count] * 3 == [self.nodes[i].getblockcount() for i in range(3)])
            assert_equal(balance_nodes, [self.nodes[i].getbalance() for i in range(3)])

        # Exercise listsinceblock with the last two blocks
        coinbase_tx_1 = self.nodes[0].listsinceblock(blocks[0])
        assert_equal(coinbase_tx_1["lastblock"], blocks[1])
        assert_equal(len(coinbase_tx_1["transactions"]), 1)
        assert_equal(coinbase_tx_1["transactions"][0]["blockhash"], blocks[1])
        assert_equal(len(self.nodes[0].listsinceblock(blocks[1])["transactions"]), 0)

        # ==Check that wallet prefers to use coins that don't exceed mempool limits =====

        # Get all non-zero utxos together
        chain_addrs = [self.nodes[0].getnewaddress(), self.nodes[0].getnewaddress()]
        singletxid = self.nodes[0].sendtoaddress(chain_addrs[0], self.nodes[0].getbalance(), "", "", True)
        self.nodes[0].generate(1)
        node0_balance = self.nodes[0].getbalance()
        # Split into two chains
        rawtx = self.nodes[0].createrawtransaction([{"txid": singletxid, "vout": 0}], {chain_addrs[0]: node0_balance / 2 - Decimal('0.01'), chain_addrs[1]: node0_balance / 2 - Decimal('0.01')})
        signedtx = self.nodes[0].signrawtransactionwithwallet(rawtx)
        singletxid = self.nodes[0].sendrawtransaction(signedtx["hex"])
        self.nodes[0].generate(1)

        # Make a long chain of unconfirmed payments without hitting mempool limit
        # Each tx we make leaves only one output of change on a chain 1 longer
        # Since the amount to send is always much less than the outputs, we only ever need one output
        # So we should be able to generate exactly chainlimit txs for each original output
        sending_addr = self.nodes[1].getnewaddress()
        txid_list = []
        for i in range(chainlimit * 2):
            txid_list.append(self.nodes[0].sendtoaddress(sending_addr, Decimal('0.0001')))
        assert_equal(self.nodes[0].getmempoolinfo()['size'], chainlimit * 2)
        assert_equal(len(txid_list), chainlimit * 2)

        # Without walletrejectlongchains, we will still generate a txid
        # The tx will be stored in the wallet but not accepted to the mempool
        extra_txid = self.nodes[0].sendtoaddress(sending_addr, Decimal('0.0001'))
        assert extra_txid not in self.nodes[0].getrawmempool()
        assert extra_txid in [tx["txid"] for tx in self.nodes[0].listtransactions()]
        self.nodes[0].abandontransaction(extra_txid)
        total_txs = len(self.nodes[0].listtransactions("*", 99999))

        # Try with walletrejectlongchains
        # Double chain limit but require combining inputs, so we pass SelectCoinsMinConf
        self.stop_node(0)
        self.start_node(0, extra_args=["-walletrejectlongchains", "-limitancestorcount=" + str(2 * chainlimit)])

        # wait for loadmempool
        timeout = 10
        while (timeout > 0 and len(self.nodes[0].getrawmempool()) < chainlimit * 2):
            time.sleep(0.5)
            timeout -= 0.5
        assert_equal(len(self.nodes[0].getrawmempool()), chainlimit * 2)

        # Prevent potential race condition when calling wallet RPCs right after restart
        self.nodes[0].syncwithvalidationinterfacequeue()

        node0_balance = self.nodes[0].getbalance()
        # With walletrejectlongchains we will not create the tx and store it in our wallet.
        assert_raises_rpc_error(-4, "Transaction has too long of a mempool chain", self.nodes[0].sendtoaddress, sending_addr, node0_balance - Decimal('0.01'))

        # Verify nothing new in wallet
        assert_equal(total_txs, len(self.nodes[0].listtransactions("*", 99999)))

        # Test getaddressinfo on external address. Note that these addresses are taken from disablewallet.py
        assert_raises_rpc_error(-5, "Invalid address", self.nodes[0].getaddressinfo, "3J98t1WpEZ73CNmQviecrnyiWrnqRhWNLy")
        address_info = self.nodes[0].getaddressinfo("yjQ5gLvGRtmq1cwc4kePLCrzQ8GVCh9Gaz")
        assert_equal(address_info['address'], "yjQ5gLvGRtmq1cwc4kePLCrzQ8GVCh9Gaz")
        assert_equal(address_info["scriptPubKey"], "76a914fd2b4d101724a76374fccbc5b6df7670a75d7cd088ac")
        assert not address_info["ismine"]
        assert not address_info["iswatchonly"]
        assert not address_info["isscript"]
        assert not address_info["ischange"]

        # Test getaddressinfo 'ischange' field on change address.
        self.nodes[0].generate(1)
        destination = self.nodes[1].getnewaddress()
        txid = self.nodes[0].sendtoaddress(destination, 0.123)
        tx = self.nodes[0].decoderawtransaction(self.nodes[0].gettransaction(txid)['hex'])
        output_addresses = [vout['scriptPubKey']['addresses'][0] for vout in tx["vout"]]
        assert len(output_addresses) > 1
        for address in output_addresses:
            ischange = self.nodes[0].getaddressinfo(address)['ischange']
            assert_equal(ischange, address != destination)
            if ischange:
                change = address
        self.nodes[0].setlabel(change, 'foobar')
        assert_equal(self.nodes[0].getaddressinfo(change)['ischange'], False)


if __name__ == '__main__':
    WalletTest().main()