text: // Copyright (c) 2012-2013 The Bitcoin Core developers
  // Copyright (c) 2017 The CCIP developers
  // Distributed under the MIT/X11 software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  #include "merkleblock.h"
  #include "serialize.h"
  #include "streams.h"
  #include "uint256.h"
  #include "version.h"
  
  #include <vector>
  
  #include <boost/test/unit_test.hpp>
  
  using namespace std;
  
  class CPartialMerkleTreeTester : public CPartialMerkleTree
  {
  public:
      // flip one bit in one of the hashes - this should break the authentication
      void Damage() {
          unsigned int n = rand() % vHash.size();
          int bit = rand() % 256;
          uint256 &hash = vHash[n];
          hash ^= ((uint256)1 << bit);
      }
  };
  
  BOOST_AUTO_TEST_SUITE(pmt_tests)
  
  BOOST_AUTO_TEST_CASE(pmt_test1)
  {
      static const unsigned int nTxCounts[] = {1, 4, 7, 17, 56, 100, 127, 256, 312, 513, 1000, 4095};
  
      for (int n = 0; n < 12; n++) {
          unsigned int nTx = nTxCounts[n];
  
          // build a block with some dummy transactions
          CBlock block;
          for (unsigned int j=0; j<nTx; j++) {
              CMutableTransaction tx;
              tx.nLockTime = rand(); // actual transaction data doesn't matter; just make the nLockTime's unique
              block.vtx.push_back(CTransaction(tx));
          }
  
          // calculate actual merkle root and height
          uint256 merkleRoot1 = block.BuildMerkleTree();
          std::vector<uint256> vTxid(nTx, 0);
          for (unsigned int j=0; j<nTx; j++)
              vTxid[j] = block.vtx[j].GetHash();
          int nHeight = 1, nTx_ = nTx;
          while (nTx_ > 1) {
              nTx_ = (nTx_+1)/2;
              nHeight++;
          }
  
          // check with random subsets with inclusion chances 1, 1/2, 1/4, ..., 1/128
          for (int att = 1; att < 15; att++) {
              // build random subset of txid's
              std::vector<bool> vMatch(nTx, false);
              std::vector<uint256> vMatchTxid1;
              for (unsigned int j=0; j<nTx; j++) {
                  bool fInclude = (rand() & ((1 << (att/2)) - 1)) == 0;
                  vMatch[j] = fInclude;
                  if (fInclude)
                      vMatchTxid1.push_back(vTxid[j]);
              }
  
              // build the partial merkle tree
              CPartialMerkleTree pmt1(vTxid, vMatch);
  
              // serialize
              CDataStream ss(SER_NETWORK, PROTOCOL_VERSION);
              ss << pmt1;
  
              // verify CPartialMerkleTree's size guarantees
              unsigned int n = std::min<unsigned int>(nTx, 1 + vMatchTxid1.size()*nHeight);
              BOOST_CHECK(ss.size() <= 10 + (258*n+7)/8);
  
              // deserialize into a tester copy
              CPartialMerkleTreeTester pmt2;
              ss >> pmt2;
  
              // extract merkle root and matched txids from copy
              std::vector<uint256> vMatchTxid2;
              uint256 merkleRoot2 = pmt2.ExtractMatches(vMatchTxid2);
  
              // check that it has the same merkle root as the original, and a valid one
              BOOST_CHECK(merkleRoot1 == merkleRoot2);
              BOOST_CHECK(merkleRoot2 != 0);
  
              // check that it contains the matched transactions (in the same order!)
              BOOST_CHECK(vMatchTxid1 == vMatchTxid2);
  
              // check that random bit flips break the authentication
              for (int j=0; j<4; j++) {
                  CPartialMerkleTreeTester pmt3(pmt2);
                  pmt3.Damage();
                  std::vector<uint256> vMatchTxid3;
                  uint256 merkleRoot3 = pmt3.ExtractMatches(vMatchTxid3);
                  BOOST_CHECK(merkleRoot3 != merkleRoot1);
              }
          }
      }
  }
  
  BOOST_AUTO_TEST_SUITE_END()
  