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  static bool DoubleEquals(double a, double b, double epsilon)
18  {
19      return std::abs(a - b) < epsilon;
20  }
21  
22  static CBlockIndex* CreateBlockIndexWithNbits(uint32_t nbits)
23  {
24      CBlockIndex* block_index = new CBlockIndex();
25      block_index->nHeight = 46367;
26      block_index->nTime = 1269211443;
27      block_index->nBits = nbits;
28      return block_index;
29  }
30  
31  static void RejectDifficultyMismatch(double difficulty, double expected_difficulty) {
32       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  }
37  
38  /* Given a BlockIndex with the provided nbits,
39   * verify that the expected difficulty results.
40   */
41  static void TestDifficulty(uint32_t nbits, double expected_difficulty)
42  {
43      CBlockIndex* block_index = CreateBlockIndexWithNbits(nbits);
44      double difficulty = GetDifficulty(*block_index);
45      delete block_index;
46  
47      RejectDifficultyMismatch(difficulty, expected_difficulty);
48  }
49  
50  BOOST_FIXTURE_TEST_SUITE(blockchain_tests, BasicTestingSetup)
51  
52  BOOST_AUTO_TEST_CASE(get_difficulty_for_very_low_target)
53  {
54      TestDifficulty(0x1f111111, 0.000001);
55  }
56  
57  BOOST_AUTO_TEST_CASE(get_difficulty_for_low_target)
58  {
59      TestDifficulty(0x1ef88f6f, 0.000016);
60  }
61  
62  BOOST_AUTO_TEST_CASE(get_difficulty_for_mid_target)
63  {
64      TestDifficulty(0x1df88f6f, 0.004023);
65  }
66  
67  BOOST_AUTO_TEST_CASE(get_difficulty_for_high_target)
68  {
69      TestDifficulty(0x1cf88f6f, 1.029916);
70  }
71  
72  BOOST_AUTO_TEST_CASE(get_difficulty_for_very_high_target)
73  {
74      TestDifficulty(0x12345678, 5913134931067755359633408.0);
75  }
76  
77  BOOST_AUTO_TEST_SUITE_END()