text: // Copyright (c) 2015 The Bitcoin Core developers
  // Distributed under the MIT/X11 software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  #include "chain.h"
  #include "chainparams.h"
  #include "pow.h"
  #include "random.h"
  #include "util.h"
  #include "test/test_bitcoin.h"
  
  #include <boost/test/unit_test.hpp>
  
  using namespace std;
  
  BOOST_FIXTURE_TEST_SUITE(pow_tests, BasicTestingSetup)
  
  /* Test calculation of next difficulty target with no constraints applying */
  BOOST_AUTO_TEST_CASE(get_next_work)
  {
      SelectParams(CBaseChainParams::MAIN);
      const Consensus::Params& params = Params().GetConsensus();
  
      int64_t nLastRetargetTime = 1517197553; // Block #543323
      CBlockIndex pindexLast;
      pindexLast.nHeight = 25810;     // First halving
      pindexLast.nTime = 1474276165;  // Block #25810
      pindexLast.nBits = 0x1a0ed6a5;
      BOOST_CHECK_EQUAL(CalculateNextWorkRequired(&pindexLast, nLastRetargetTime, params), 0x1a03b5a9);   // 0x1a03b5a9 is dummy value (436450729) - Fix for KGW
  }
  
  /* Test the constraint on the upper bound for next work */
  BOOST_AUTO_TEST_CASE(get_next_work_pow_limit)
  {
      SelectParams(CBaseChainParams::MAIN);
      const Consensus::Params& params = Params().GetConsensus();
  
      int64_t nLastRetargetTime = 1471801377; // Block #0
      CBlockIndex pindexLast;
      pindexLast.nHeight = 2015;
      pindexLast.nTime = 1472355316;  // Block #2015
      pindexLast.nBits = 0x1a01c546;
      BOOST_CHECK_EQUAL(CalculateNextWorkRequired(&pindexLast, nLastRetargetTime, params), 0x1a071518);   // 0x1a071518 is dummy value (436671768) - Fix for KGW
  }
  
  /* Test the constraint on the lower bound for actual time taken */
  BOOST_AUTO_TEST_CASE(get_next_work_lower_limit_actual)
  {
      SelectParams(CBaseChainParams::MAIN);
      const Consensus::Params& params = Params().GetConsensus();
  
      int64_t nLastRetargetTime = 1279008237; // Block #66528
      CBlockIndex pindexLast;
      pindexLast.nHeight = 68543;
      pindexLast.nTime = 1279297671;  // Block #68543
      pindexLast.nBits = 0x1c05a3f4;
      BOOST_CHECK_EQUAL(CalculateNextWorkRequired(&pindexLast, nLastRetargetTime, params), 0x1c168fd0);    // 0x1c168fd0 is dummy value (471240656) - Fix for KGW
  }
  
  /* Test the constraint on the upper bound for actual time taken */
  BOOST_AUTO_TEST_CASE(get_next_work_upper_limit_actual)
  {
      SelectParams(CBaseChainParams::MAIN);
      const Consensus::Params& params = Params().GetConsensus();
  
      int64_t nLastRetargetTime = 1263163443; // NOTE: Not an actual block time
      CBlockIndex pindexLast;
      pindexLast.nHeight = 46367;
      pindexLast.nTime = 1269211443;  // Block #46367
      pindexLast.nBits = 0x1c387f6f;
      BOOST_CHECK_EQUAL(CalculateNextWorkRequired(&pindexLast, nLastRetargetTime, params), 0x1d00e1fd);
  }
  
  BOOST_AUTO_TEST_CASE(GetBlockProofEquivalentTime_test)
  {
      SelectParams(CBaseChainParams::MAIN);
      const Consensus::Params& params = Params().GetConsensus();
  
      std::vector<CBlockIndex> blocks(10000);
      for (int i = 0; i < 10000; i++) {
          blocks[i].pprev = i ? &blocks[i - 1] : NULL;
          blocks[i].nHeight = i;
          blocks[i].nTime = 1269211443 + i * params.nPowTargetSpacing;
          blocks[i].nBits = 0x207fffff; /* target 0x7fffff000... */
          blocks[i].nChainWork = i ? blocks[i - 1].nChainWork + GetBlockProof(blocks[i - 1]) : arith_uint256(0);
      }
  
      for (int j = 0; j < 1000; j++) {
          CBlockIndex *p1 = &blocks[GetRand(10000)];
          CBlockIndex *p2 = &blocks[GetRand(10000)];
          CBlockIndex *p3 = &blocks[GetRand(10000)];
  
          int64_t tdiff = GetBlockProofEquivalentTime(*p1, *p2, *p3, params);
          BOOST_CHECK_EQUAL(tdiff, p1->GetBlockTime() - p2->GetBlockTime());
      }
  }
  
  BOOST_AUTO_TEST_SUITE_END()
  