Add FeeFrac unit tests

Co-authored-by: Suhas Daftuar <sdaftuar@chaincode.com>

src/Makefile.test.include

@@ -93,6 +93,7 @@ BITCOIN_TESTS =\
   test/denialofservice_tests.cpp \
   test/descriptor_tests.cpp \
   test/disconnected_transactions.cpp \
+  test/feefrac_tests.cpp \
   test/flatfile_tests.cpp \
   test/fs_tests.cpp \
   test/getarg_tests.cpp \

src/test/feefrac_tests.cpp

@@ -0,0 +1,124 @@
+// Copyright (c) 2024-present 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 <util/feefrac.h>
+#include <random.h>
+
+#include <boost/test/unit_test.hpp>
+
+BOOST_AUTO_TEST_SUITE(feefrac_tests)
+
+BOOST_AUTO_TEST_CASE(feefrac_operators)
+{
+    FeeFrac p1{1000, 100}, p2{500, 300};
+    FeeFrac sum{1500, 400};
+    FeeFrac diff{500, -200};
+    FeeFrac empty{0, 0};
+    FeeFrac zero_fee{0, 1}; // zero-fee allowed
+
+    BOOST_CHECK(empty == FeeFrac{}); // same as no-args
+
+    BOOST_CHECK(p1 == p1);
+    BOOST_CHECK(p1 + p2 == sum);
+    BOOST_CHECK(p1 - p2 == diff);
+
+    FeeFrac p3{2000, 200};
+    BOOST_CHECK(p1 != p3); // feefracs only equal if both fee and size are same
+    BOOST_CHECK(p2 != p3);
+
+    FeeFrac p4{3000, 300};
+    BOOST_CHECK(p1 == p4-p3);
+    BOOST_CHECK(p1 + p3 == p4);
+
+    // Fee-rate comparison
+    BOOST_CHECK(p1 > p2);
+    BOOST_CHECK(p1 >= p2);
+    BOOST_CHECK(p1 >= p4-p3);
+    BOOST_CHECK(!(p1 >> p3)); // not strictly better
+    BOOST_CHECK(p1 >> p2); // strictly greater feerate
+
+    BOOST_CHECK(p2 < p1);
+    BOOST_CHECK(p2 <= p1);
+    BOOST_CHECK(p1 <= p4-p3);
+    BOOST_CHECK(!(p3 << p1)); // not strictly worse
+    BOOST_CHECK(p2 << p1); // strictly lower feerate
+
+    // "empty" comparisons
+    BOOST_CHECK(!(p1 >> empty)); // << will always result in false
+    BOOST_CHECK(!(p1 << empty));
+    BOOST_CHECK(!(empty >> empty));
+    BOOST_CHECK(!(empty << empty));
+
+    // empty is always bigger than everything else
+    BOOST_CHECK(empty > p1);
+    BOOST_CHECK(empty > p2);
+    BOOST_CHECK(empty > p3);
+    BOOST_CHECK(empty >= p1);
+    BOOST_CHECK(empty >= p2);
+    BOOST_CHECK(empty >= p3);
+
+    // check "max" values for comparison
+    FeeFrac oversized_1{4611686000000, 4000000};
+    FeeFrac oversized_2{184467440000000, 100000};
+
+    BOOST_CHECK(oversized_1 < oversized_2);
+    BOOST_CHECK(oversized_1 <= oversized_2);
+    BOOST_CHECK(oversized_1 << oversized_2);
+    BOOST_CHECK(oversized_1 != oversized_2);
+
+    // Tests paths that use double arithmetic
+    FeeFrac busted{(static_cast<int64_t>(INT32_MAX)) + 1, INT32_MAX};
+    BOOST_CHECK(!(busted < busted));
+
+    FeeFrac max_fee{2100000000000000, INT32_MAX};
+    BOOST_CHECK(!(max_fee < max_fee));
+    BOOST_CHECK(!(max_fee > max_fee));
+    BOOST_CHECK(max_fee <= max_fee);
+    BOOST_CHECK(max_fee >= max_fee);
+
+    FeeFrac max_fee2{1, 1};
+    BOOST_CHECK(max_fee >= max_fee2);
+
+}
+
+BOOST_AUTO_TEST_CASE(build_diagram_test)
+{
+    FeeFrac p1{1000, 100};
+    FeeFrac empty{0, 0};
+    FeeFrac zero_fee{0, 1};
+    FeeFrac oversized_1{4611686000000, 4000000};
+    FeeFrac oversized_2{184467440000000, 100000};
+
+    // Diagram-building will reorder chunks
+    std::vector<FeeFrac> chunks;
+    chunks.push_back(p1);
+    chunks.push_back(zero_fee);
+    chunks.push_back(empty);
+    chunks.push_back(oversized_1);
+    chunks.push_back(oversized_2);
+
+    // Caller in charge of sorting chunks in case chunk size limit
+    // differs from cluster size limit
+    std::sort(chunks.begin(), chunks.end(), [](const FeeFrac& a, const FeeFrac& b) { return a > b; });
+
+    // Chunks are now sorted in reverse order (largest first)
+    BOOST_CHECK(chunks[0] == empty); // empty is considered "highest" fee
+    BOOST_CHECK(chunks[1] == oversized_2);
+    BOOST_CHECK(chunks[2] == oversized_1);
+    BOOST_CHECK(chunks[3] == p1);
+    BOOST_CHECK(chunks[4] == zero_fee);
+
+    std::vector<FeeFrac> generated_diagram{BuildDiagramFromChunks(chunks)};
+    BOOST_CHECK(generated_diagram.size() == 1 + chunks.size());
+
+    // Prepended with an empty, then the chunks summed in order as above
+    BOOST_CHECK(generated_diagram[0] == empty);
+    BOOST_CHECK(generated_diagram[1] == empty);
+    BOOST_CHECK(generated_diagram[2] == oversized_2);
+    BOOST_CHECK(generated_diagram[3] == oversized_2 + oversized_1);
+    BOOST_CHECK(generated_diagram[4] == oversized_2 + oversized_1 + p1);
+    BOOST_CHECK(generated_diagram[5] == oversized_2 + oversized_1 + p1 + zero_fee);
+}
+
+BOOST_AUTO_TEST_SUITE_END()