1 files changed, 77 insertions, 0 deletions
diff --git a/src/test/blockchain_tests.cpp b/src/test/blockchain_tests.cpp
new file mode 100644
index 0000000000..c8e8cdeeb3
--- /dev/null
+++ b/src/test/blockchain_tests.cpp
@@ -0,0 +1,77 @@
+// Copyright (c) 2017-2020 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <boost/test/unit_test.hpp>
+
+#include <stdlib.h>
+
+#include <chain.h>
+#include <rpc/blockchain.h>
+#include <test/util/setup_common.h>
+#include <util/string.h>
+
+/* Equality between doubles is imprecise. Comparison should be done
+ * with a small threshold of tolerance, rather than exact equality.
+ */
+static bool DoubleEquals(double a, double b, double epsilon)
+{
+    return std::abs(a - b) < epsilon;
+}
+
+static CBlockIndex* CreateBlockIndexWithNbits(uint32_t nbits)
+{
+    CBlockIndex* block_index = new CBlockIndex();
+    block_index->nHeight = 46367;
+    block_index->nTime = 1269211443;
+    block_index->nBits = nbits;
+    return block_index;
+}
+
+static void RejectDifficultyMismatch(double difficulty, double expected_difficulty) {
+     BOOST_CHECK_MESSAGE(
+        DoubleEquals(difficulty, expected_difficulty, 0.00001),
+        "Difficulty was " + ToString(difficulty)
+            + " but was expected to be " + ToString(expected_difficulty));
+}
+
+/* Given a BlockIndex with the provided nbits,
+ * verify that the expected difficulty results.
+ */
+static void TestDifficulty(uint32_t nbits, double expected_difficulty)
+{
+    CBlockIndex* block_index = CreateBlockIndexWithNbits(nbits);
+    double difficulty = GetDifficulty(block_index);
+    delete block_index;
+
+    RejectDifficultyMismatch(difficulty, expected_difficulty);
+}
+
+BOOST_FIXTURE_TEST_SUITE(blockchain_tests, BasicTestingSetup)
+
+BOOST_AUTO_TEST_CASE(get_difficulty_for_very_low_target)
+{
+    TestDifficulty(0x1f111111, 0.000001);
+}
+
+BOOST_AUTO_TEST_CASE(get_difficulty_for_low_target)
+{
+    TestDifficulty(0x1ef88f6f, 0.000016);
+}
+
+BOOST_AUTO_TEST_CASE(get_difficulty_for_mid_target)
+{
+    TestDifficulty(0x1df88f6f, 0.004023);
+}
+
+BOOST_AUTO_TEST_CASE(get_difficulty_for_high_target)
+{
+    TestDifficulty(0x1cf88f6f, 1.029916);
+}
+
+BOOST_AUTO_TEST_CASE(get_difficulty_for_very_high_target)
+{
+    TestDifficulty(0x12345678, 5913134931067755359633408.0);
+}
+
+BOOST_AUTO_TEST_SUITE_END()