text: #!/usr/bin/env python3
  # Copyright (c) 2016 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 version bits warning system.
  
  Generate chains with block versions that appear to be signalling unknown
  soft-forks, and test that warning alerts are generated.
  """
  import os
  import re
  
  from test_framework.blocktools import create_block, create_coinbase
  from test_framework.messages import msg_block
  from test_framework.mininode import P2PInterface, network_thread_start, mininode_lock
  from test_framework.test_framework import BitcoinTestFramework
  from test_framework.util import wait_until
  
  VB_PERIOD = 144           # versionbits period length for regtest
  VB_THRESHOLD = 108        # versionbits activation threshold for regtest
  VB_TOP_BITS = 0x20000000
  VB_UNKNOWN_BIT = 27       # Choose a bit unassigned to any deployment
  VB_UNKNOWN_VERSION = VB_TOP_BITS | (1 << VB_UNKNOWN_BIT)
  
  WARN_UNKNOWN_RULES_MINED = "Unknown block versions being mined! It's possible unknown rules are in effect"
  WARN_UNKNOWN_RULES_ACTIVE = "unknown new rules activated (versionbit {})".format(VB_UNKNOWN_BIT)
  VB_PATTERN = re.compile("Warning: unknown new rules activated.*versionbit")
  
  class VersionBitsWarningTest(BitcoinTestFramework):
      def set_test_params(self):
          self.setup_clean_chain = True
          self.num_nodes = 1
  
      def setup_network(self):
          self.alert_filename = os.path.join(self.options.tmpdir, "alert.txt")
          # Open and close to create zero-length file
          with open(self.alert_filename, 'w', encoding='utf8'):
              pass
          self.extra_args = [["-alertnotify=echo %s >> \"" + self.alert_filename + "\""]]
          self.setup_nodes()
  
      def send_blocks_with_version(self, peer, numblocks, version):
          """Send numblocks blocks to peer with version set"""
          tip = self.nodes[0].getbestblockhash()
          height = self.nodes[0].getblockcount()
          block_time = self.nodes[0].getblockheader(tip)["time"] + 1
          tip = int(tip, 16)
  
          for _ in range(numblocks):
              block = create_block(tip, create_coinbase(height + 1), block_time)
              block.nVersion = version
              block.solve()
              peer.send_message(msg_block(block))
              block_time += 1
              height += 1
              tip = block.sha256
          peer.sync_with_ping()
  
      def versionbits_in_alert_file(self):
          """Test that the versionbits warning has been written to the alert file."""
          alert_text = open(self.alert_filename, 'r', encoding='utf8').read()
          return VB_PATTERN.search(alert_text) is not None
  
      def run_test(self):
          # Handy alias
          node = self.nodes[0]
          node.add_p2p_connection(P2PInterface())
          network_thread_start()
          node.p2p.wait_for_verack()
  
          # Mine one period worth of blocks
          node.generate(VB_PERIOD)
  
          self.log.info("Check that there is no warning if previous VB_BLOCKS have <VB_THRESHOLD blocks with unknown versionbits version.")
          # Build one period of blocks with < VB_THRESHOLD blocks signaling some unknown bit
          self.send_blocks_with_version(node.p2p, VB_THRESHOLD - 1, VB_UNKNOWN_VERSION)
          node.generate(VB_PERIOD - VB_THRESHOLD + 1)
  
          # Check that we're not getting any versionbit-related errors in get*info()
          assert(not VB_PATTERN.match(node.getmininginfo()["warnings"]))
          assert(not VB_PATTERN.match(node.getnetworkinfo()["warnings"]))
  
          self.log.info("Check that there is a warning if >50 blocks in the last 100 were an unknown version")
          # Build one period of blocks with VB_THRESHOLD blocks signaling some unknown bit
          self.send_blocks_with_version(node.p2p, VB_THRESHOLD, VB_UNKNOWN_VERSION)
          node.generate(VB_PERIOD - VB_THRESHOLD)
  
          # Check that get*info() shows the 51/100 unknown block version error.
          assert(WARN_UNKNOWN_RULES_MINED in node.getmininginfo()["warnings"])
          assert(WARN_UNKNOWN_RULES_MINED in node.getnetworkinfo()["warnings"])
  
          self.log.info("Check that there is a warning if previous VB_BLOCKS have >=VB_THRESHOLD blocks with unknown versionbits version.")
          # Mine a period worth of expected blocks so the generic block-version warning
          # is cleared. This will move the versionbit state to ACTIVE.
          node.generate(VB_PERIOD)
  
          # Stop-start the node. This is required because luckycoinorod will only warn once about unknown versions or unknown rules activating.
          self.restart_node(0)
  
          # Generating one block guarantees that we'll get out of IBD
          node.generate(1)
          wait_until(lambda: not node.getblockchaininfo()['initialblockdownload'], timeout=10, lock=mininode_lock)
          # Generating one more block will be enough to generate an error.
          node.generate(1)
          # Check that get*info() shows the versionbits unknown rules warning
          assert(WARN_UNKNOWN_RULES_ACTIVE in node.getmininginfo()["warnings"])
          assert(WARN_UNKNOWN_RULES_ACTIVE in node.getnetworkinfo()["warnings"])
          # Check that the alert file shows the versionbits unknown rules warning
          wait_until(lambda: self.versionbits_in_alert_file(), timeout=60)
  
  if __name__ == '__main__':
      VersionBitsWarningTest().main()
  