text: #!/usr/bin/env python3
  # Copyright (c) 2014-2015 The Bitcoin Core developers
  # Copyright (c) 2015-2017 The Bitcoin Unlimited developers
  # Distributed under the MIT software license, see the accompanying
  # file COPYING or http://www.opensource.org/licenses/mit-license.php.
  import test_framework.loginit
  #
  # Test InvalidateBlock code
  #
  
  import time
  
  from test_framework.test_framework import BitcoinTestFramework
  from test_framework.util import *
  
  
  def retryWhile(fn, exc, excStr=None):
      while 1:
          try:
              fn()
              break
          except exc as e:
              if (not excStr is None):
                  if not excStr in str(e):
                      raise
          time.sleep(.5)
  
  
  class InvalidateTest(BitcoinTestFramework):
  
  
      def setup_chain(self):
          print("Initializing test directory "+self.options.tmpdir)
          initialize_chain_clean(self.options.tmpdir, 4)
  
      def setup_network(self):
          self.nodes = []
          self.is_network_split = False 
          self.nodes.append(start_node(0, self.options.tmpdir, ["-debug"]))
          self.nodes.append(start_node(1, self.options.tmpdir, ["-debug"]))
          self.nodes.append(start_node(2, self.options.tmpdir, ["-debug"]))
  
      def run_test(self):
          print("Make sure we repopulate setBlockIndexCandidates after InvalidateBlock:")
          print("Mine 4 blocks on Node 0")
          self.nodes[0].generate(4)
          assert(self.nodes[0].getblockcount() == 4)
          besthash = self.nodes[0].getbestblockhash()
  
          print("Mine competing 6 blocks on Node 1")
          self.nodes[1].generate(6)
          assert(self.nodes[1].getblockcount() == 6)
  
          print("Connect nodes to force a reorg")
          connect_nodes_bi(self.nodes,0,1)
          sync_blocks(self.nodes[0:2])
          assert(self.nodes[0].getblockcount() == 6)
          badhash = self.nodes[1].getblockhash(2)
  
          print("Invalidate block 2 on node 0 and verify we reorg to node 0's original chain")
          self.nodes[0].invalidateblock(badhash)
          newheight = self.nodes[0].getblockcount()
          newhash = self.nodes[0].getbestblockhash()
          if (newheight != 4 or newhash != besthash):
              raise AssertionError("Wrong tip for node0, hash %s, height %d"%(newhash,newheight))
  
          print("\nMake sure we won't reorg to a lower work chain:")
          connect_nodes_bi(self.nodes,1,2)
          print("Sync node 2 to node 1 so both have 6 blocks")
          sync_blocks(self.nodes[1:3])
          assert(self.nodes[2].getblockcount() == 6)
          print("Invalidate block 5 on node 1 so its tip is now at 4")
          self.nodes[1].invalidateblock(self.nodes[1].getblockhash(5))
          assert(self.nodes[1].getblockcount() == 4)
          print("Invalidate block 3 on node 2, so its tip is now 2")
          self.nodes[2].invalidateblock(self.nodes[2].getblockhash(3))
          assert(self.nodes[2].getblockcount() == 2)
          print("..and then mine a block")
          self.nodes[2].generate(1)
          print("Verify all nodes are at the right height")
          time.sleep(5)
          for i in range(3):
              print(i,self.nodes[i].getblockcount())
          assert(self.nodes[2].getblockcount() == 3)
          assert(self.nodes[0].getblockcount() == 4)
          node1height = self.nodes[1].getblockcount()
          if node1height < 4:
              raise AssertionError("Node 1 reorged to a lower height: %d"%node1height)
  
          self.testChainSyncWithLongerInvalid()
  
  
      def testChainSyncWithLongerInvalid(self):
          print("verify that IBD continues on a separate chain after a block is invalidated")
  
          ret = self.nodes[0].generate(50)
          # after the headers propagate, invalidate the block
          retryWhile(lambda: self.nodes[1].invalidateblock(ret[0]), JSONRPCException, "Block not found")
          # now generate a competing chain
          ret1 = self.nodes[1].generate(25)
  
          # now start up a new node to sync with one of the chains
          self.nodes.append(start_node(3, self.options.tmpdir, ["-debug"]))
          connect_nodes_bi(self.nodes,0,3)
          connect_nodes_bi(self.nodes,1,3)
          # invalidate the longest chain
          self.nodes[3].invalidateblock(ret[0])
          # give it time to sync with the shorter chain on node 1
          print("allowing node 3 to sync")
          time.sleep(5)
          blocks1 = self.nodes[1].getblockcount()
          nblocks = self.nodes[3].getblockcount()
          # test if it is synced
          if nblocks != blocks1:
              print("ERROR: node 3 did not sync with longest valid chain")
              print("chain tips on 0: %s" % str(self.nodes[0].getchaintips()))
              print("chain tips on 1: %s" % str(self.nodes[1].getchaintips()))
              print("chain tips on 3: %s" % str(self.nodes[3].getchaintips()))
              print("longest chain on 3: %s" % str(self.nodes[3].getblockcount()))
          # enable when fixed: assert(nblocks == blocks1);  # since I invalidated a block on 0's chain, I should be caught up with 1
  
          print("Now make the other chain (with no invalid blocks) longer")
          ret1 = self.nodes[1].generate(50)
          time.sleep(5)
          blocks1 = self.nodes[1].getblockcount()
          nblocks = self.nodes[3].getblockcount()
          # test if it is synced
          if nblocks != blocks1:
              print("node 3 did not sync up")
              print("chain tips on 0: %s" % str(self.nodes[0].getchaintips()))
              print("chain tips on 1: %s" % str(self.nodes[1].getchaintips()))
              print("chain tips on 3: %s" % str(self.nodes[3].getchaintips()))
              print("longest chain on 3: %s" % str(self.nodes[3].getblockcount()))
          else:
              print("node 1 synced with longest chain")
  
  
         
  if __name__ == '__main__':
      InvalidateTest().main()
  
  def Test():
      t = InvalidateTest()
      bitcoinConf = {
      "debug":["net","blk","thin","mempool","req","bench","evict"], # "lck"
      "blockprioritysize":2000000  # we don't want any transactions rejected due to insufficient fees...
       }
      t.main(["--nocleanup","--noshutdown", "--tmpdir=/ramdisk/test"],bitcoinConf,None)
  