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       1                 :            : // Copyright (c) 2017-2022 The Bitcoin Core developers
       2                 :            : // Distributed under the MIT software license, see the accompanying
       3                 :            : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
       4                 :            : 
       5                 :            : #include <boost/test/unit_test.hpp>
       6                 :            : 
       7                 :            : #include <chain.h>
       8                 :            : #include <rpc/blockchain.h>
       9                 :            : #include <test/util/setup_common.h>
      10                 :            : #include <util/string.h>
      11                 :            : 
      12                 :            : #include <cstdlib>
      13                 :            : 
      14                 :            : /* Equality between doubles is imprecise. Comparison should be done
      15                 :            :  * with a small threshold of tolerance, rather than exact equality.
      16                 :            :  */
      17                 :          0 : static bool DoubleEquals(double a, double b, double epsilon)
      18                 :          0 : {
      19                 :          0 :     return std::abs(a - b) < epsilon;
      20                 :            : }
      21                 :            : 
      22                 :          0 : static CBlockIndex* CreateBlockIndexWithNbits(uint32_t nbits)
      23                 :            : {
      24                 :          0 :     CBlockIndex* block_index = new CBlockIndex();
      25                 :          0 :     block_index->nHeight = 46367;
      26                 :          0 :     block_index->nTime = 1269211443;
      27                 :          0 :     block_index->nBits = nbits;
      28                 :          0 :     return block_index;
      29                 :          0 : }
      30                 :            : 
      31                 :          0 : static void RejectDifficultyMismatch(double difficulty, double expected_difficulty) {
      32                 :          0 :      BOOST_CHECK_MESSAGE(
      33                 :            :         DoubleEquals(difficulty, expected_difficulty, 0.00001),
      34                 :            :         "Difficulty was " + ToString(difficulty)
      35                 :            :             + " but was expected to be " + ToString(expected_difficulty));
      36                 :          0 : }
      37                 :            : 
      38                 :            : /* Given a BlockIndex with the provided nbits,
      39                 :            :  * verify that the expected difficulty results.
      40                 :            :  */
      41                 :          0 : static void TestDifficulty(uint32_t nbits, double expected_difficulty)
      42                 :            : {
      43                 :          0 :     CBlockIndex* block_index = CreateBlockIndexWithNbits(nbits);
      44                 :          0 :     double difficulty = GetDifficulty(block_index);
      45                 :          0 :     delete block_index;
      46                 :            : 
      47                 :          0 :     RejectDifficultyMismatch(difficulty, expected_difficulty);
      48                 :          0 : }
      49                 :            : 
      50                 :          0 : BOOST_FIXTURE_TEST_SUITE(blockchain_tests, BasicTestingSetup)
      51                 :            : 
      52                 :          0 : BOOST_AUTO_TEST_CASE(get_difficulty_for_very_low_target)
      53                 :            : {
      54                 :          0 :     TestDifficulty(0x1f111111, 0.000001);
      55                 :          0 : }
      56                 :            : 
      57                 :          0 : BOOST_AUTO_TEST_CASE(get_difficulty_for_low_target)
      58                 :            : {
      59                 :          0 :     TestDifficulty(0x1ef88f6f, 0.000016);
      60                 :          0 : }
      61                 :            : 
      62                 :          0 : BOOST_AUTO_TEST_CASE(get_difficulty_for_mid_target)
      63                 :            : {
      64                 :          0 :     TestDifficulty(0x1df88f6f, 0.004023);
      65                 :          0 : }
      66                 :            : 
      67                 :          0 : BOOST_AUTO_TEST_CASE(get_difficulty_for_high_target)
      68                 :            : {
      69                 :          0 :     TestDifficulty(0x1cf88f6f, 1.029916);
      70                 :          0 : }
      71                 :            : 
      72                 :          0 : BOOST_AUTO_TEST_CASE(get_difficulty_for_very_high_target)
      73                 :            : {
      74                 :          0 :     TestDifficulty(0x12345678, 5913134931067755359633408.0);
      75                 :          0 : }
      76                 :            : 
      77                 :          0 : BOOST_AUTO_TEST_SUITE_END()