new_contents: #!/usr/bin/env python3
  # Copyright (c) 2020 The Bitcoin Core developers
  # Distributed under the MIT software license, see the accompanying
  # file COPYING or http://www.opensource.org/licenses/mit-license.php.
  """Tests that a mempool transaction expires after a given timeout and that its
  children are removed as well.
  
  Both the default expiry timeout defined by DEFAULT_MEMPOOL_EXPIRY and a user
  definable expiry timeout via the '-mempoolexpiry=<n>' command line argument
  (<n> is the timeout in hours) are tested.
  """
  
  from datetime import timedelta
  
  from test_framework.test_framework import BitcoinTestFramework
  from test_framework.util import (
      assert_equal,
      assert_raises_rpc_error,
      find_vout_for_address,
  )
  
  DEFAULT_MEMPOOL_EXPIRY = 336  # hours
  CUSTOM_MEMPOOL_EXPIRY = 10  # hours
  
  
  class MempoolExpiryTest(BitcoinTestFramework):
      def set_test_params(self):
          self.num_nodes = 1
  
      def skip_test_if_missing_module(self):
          self.skip_if_no_wallet()
  
      def test_transaction_expiry(self, timeout):
          """Tests that a transaction expires after the expiry timeout and its
          children are removed as well."""
          node = self.nodes[0]
  
          # Send a parent transaction that will expire.
          parent_address = node.getnewaddress()
          parent_txid = node.sendtoaddress(parent_address, 1.0)
  
          # Set the mocktime to the arrival time of the parent transaction.
          entry_time = node.getmempoolentry(parent_txid)['time']
          node.setmocktime(entry_time)
  
          # Create child transaction spending the parent transaction
          vout = find_vout_for_address(node, parent_txid, parent_address)
          inputs = [{'txid': parent_txid, 'vout': vout}]
          outputs = {node.getnewaddress(): 0.99}
          child_raw = node.createrawtransaction(inputs, outputs)
          child_signed = node.signrawtransactionwithwallet(child_raw)['hex']
  
          # Let half of the timeout elapse and broadcast the child transaction.
          half_expiry_time = entry_time + int(60 * 60 * timeout / 2)
          node.setmocktime(half_expiry_time)
          child_txid = node.sendrawtransaction(child_signed)
          self.log.info('Broadcast child transaction after {} hours.'.format(
              timedelta(seconds=(half_expiry_time - entry_time))))
  
          # Let most of the timeout elapse and check that the parent tx is still
          # in the mempool.
          nearly_expiry_time = entry_time + 60 * 60 * timeout - 5
          node.setmocktime(nearly_expiry_time)
          # Expiry of mempool transactions is only checked when a new transaction
          # is added to the to the mempool.
          node.sendtoaddress(node.getnewaddress(), 1.0)
          self.log.info('Test parent tx not expired after {} hours.'.format(
              timedelta(seconds=(nearly_expiry_time - entry_time))))
          assert_equal(entry_time, node.getmempoolentry(parent_txid)['time'])
  
          # Transaction should be evicted from the mempool after the expiry time
          # has passed.
          expiry_time = entry_time + 60 * 60 * timeout + 5
          node.setmocktime(expiry_time)
          # Expiry of mempool transactions is only checked when a new transaction
          # is added to the to the mempool.
          node.sendtoaddress(node.getnewaddress(), 1.0)
          self.log.info('Test parent tx expiry after {} hours.'.format(
              timedelta(seconds=(expiry_time - entry_time))))
          assert_raises_rpc_error(-5, 'Transaction not in mempool',
                                  node.getmempoolentry, parent_txid)
  
          # The child transaction should be removed from the mempool as well.
          self.log.info('Test child tx is evicted as well.')
          assert_raises_rpc_error(-5, 'Transaction not in mempool',
                                  node.getmempoolentry, child_txid)
  
      def run_test(self):
          self.log.info('Test default mempool expiry timeout of {} hours.'.format(
              DEFAULT_MEMPOOL_EXPIRY))
          self.test_transaction_expiry(DEFAULT_MEMPOOL_EXPIRY)
  
          self.log.info('Test custom mempool expiry timeout of {} hours.'.format(
              CUSTOM_MEMPOOL_EXPIRY))
          self.restart_node(
              0, ['-mempoolexpiry={}'.format(CUSTOM_MEMPOOL_EXPIRY)])
          self.test_transaction_expiry(CUSTOM_MEMPOOL_EXPIRY)
  
  
  if __name__ == '__main__':
      MempoolExpiryTest().main()
  
subject: test that transactions expire from mempool