Merge branch 'pratik/otel-phase4-consensus-tracing' into pratik/otel-phase5-docs-deployment

src/tests/libxrpl/CMakeLists.txt

@@ -29,6 +29,8 @@ set(test_modules
     basics
     crypto
     json
+    resource
+    shamap
     tx
     protocol_autogen
     telemetry

src/tests/libxrpl/basics/Buffer.cpp

@@ -0,0 +1,260 @@
+#include <xrpl/basics/Buffer.h>
+
+#include <xrpl/basics/Slice.h>
+
+#include <gtest/gtest.h>
+
+#include <cstddef>
+#include <cstdint>
+#include <cstring>
+#include <type_traits>
+#include <utility>
+
+namespace xrpl::test {
+
+struct BufferTest : public ::testing::Test
+{
+    static bool
+    sane(Buffer const& b)
+    {
+        if (b.empty())
+            return b.data() == nullptr;
+
+        return b.data() != nullptr;
+    }
+};
+
+TEST_F(BufferTest, buffer)
+{
+    std::uint8_t const data[] = {0xa8, 0xa1, 0x38, 0x45, 0x23, 0xec, 0xe4, 0x23, 0x71, 0x6d, 0x2a,
+                                 0x18, 0xb4, 0x70, 0xcb, 0xf5, 0xac, 0x2d, 0x89, 0x4d, 0x19, 0x9c,
+                                 0xf0, 0x2c, 0x15, 0xd1, 0xf9, 0x9b, 0x66, 0xd2, 0x30, 0xd3};
+
+    Buffer const b0;
+    EXPECT_TRUE(sane(b0));
+    EXPECT_TRUE(b0.empty());
+
+    Buffer b1{0};
+    EXPECT_TRUE(sane(b1));
+    EXPECT_TRUE(b1.empty());
+    std::memcpy(b1.alloc(16), data, 16);
+    EXPECT_TRUE(sane(b1));
+    EXPECT_FALSE(b1.empty());
+    EXPECT_EQ(b1.size(), 16);
+
+    Buffer b2{b1.size()};
+    EXPECT_TRUE(sane(b2));
+    EXPECT_FALSE(b2.empty());
+    EXPECT_EQ(b2.size(), b1.size());
+    std::memcpy(b2.data(), data + 16, 16);
+
+    Buffer b3{data, sizeof(data)};
+    EXPECT_TRUE(sane(b3));
+    EXPECT_FALSE(b3.empty());
+    EXPECT_EQ(b3.size(), sizeof(data));
+    EXPECT_EQ(std::memcmp(b3.data(), data, b3.size()), 0);
+
+    // Check equality and inequality comparisons.
+    // For code readability, we want to use general
+    // EXPECT_TRUE instead of specific EXPECT_EQ etc.
+    EXPECT_TRUE(b0 == b0);
+    EXPECT_TRUE(b0 != b1);
+    EXPECT_TRUE(b1 == b1);
+    EXPECT_TRUE(b1 != b2);
+    EXPECT_TRUE(b2 != b3);
+
+    // Check copy constructors and copy assignments:
+    {
+        Buffer x{b0};
+        EXPECT_EQ(x, b0);
+        EXPECT_TRUE(sane(x));
+        Buffer y{b1};
+        EXPECT_EQ(y, b1);
+        EXPECT_TRUE(sane(y));
+        x = b2;
+        EXPECT_EQ(x, b2);
+        EXPECT_TRUE(sane(x));
+        x = y;
+        EXPECT_EQ(x, y);
+        EXPECT_TRUE(sane(x));
+        y = b3;
+        EXPECT_EQ(y, b3);
+        EXPECT_TRUE(sane(y));
+        x = b0;
+        EXPECT_EQ(x, b0);
+        EXPECT_TRUE(sane(x));
+#if defined(__clang__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wself-assign-overloaded"
+#endif
+
+        x = x;
+        EXPECT_EQ(x, b0);
+        EXPECT_TRUE(sane(x));
+        y = y;
+        EXPECT_EQ(y, b3);
+        EXPECT_TRUE(sane(y));
+
+#if defined(__clang__)
+#pragma clang diagnostic pop
+#endif
+    }
+
+    // Check move constructor & move assignments:
+    {
+        static_assert(std::is_nothrow_move_constructible_v<Buffer>);
+        static_assert(std::is_nothrow_move_assignable_v<Buffer>);
+
+        {  // Move-construct from empty buf
+            Buffer x;
+            Buffer const y{std::move(x)};
+            EXPECT_TRUE(sane(x));    // NOLINT(bugprone-use-after-move)
+            EXPECT_TRUE(x.empty());  // NOLINT(bugprone-use-after-move)
+            EXPECT_TRUE(sane(y));
+            EXPECT_TRUE(y.empty());
+            EXPECT_EQ(x, y);  // NOLINT(bugprone-use-after-move)
+        }
+
+        {  // Move-construct from non-empty buf
+            Buffer x{b1};
+            Buffer const y{std::move(x)};
+            EXPECT_TRUE(sane(x));    // NOLINT(bugprone-use-after-move)
+            EXPECT_TRUE(x.empty());  // NOLINT(bugprone-use-after-move)
+            EXPECT_TRUE(sane(y));
+            EXPECT_EQ(y, b1);
+        }
+
+        {  // Move assign empty buf to empty buf
+            Buffer x;
+            Buffer y;
+
+            x = std::move(y);
+            EXPECT_TRUE(sane(x));
+            EXPECT_TRUE(x.empty());
+            EXPECT_TRUE(sane(y));    // NOLINT(bugprone-use-after-move)
+            EXPECT_TRUE(y.empty());  // NOLINT(bugprone-use-after-move)
+        }
+
+        {  // Move assign non-empty buf to empty buf
+            Buffer x;
+            Buffer y{b1};
+
+            x = std::move(y);
+            EXPECT_TRUE(sane(x));
+            EXPECT_EQ(x, b1);
+            EXPECT_TRUE(sane(y));    // NOLINT(bugprone-use-after-move)
+            EXPECT_TRUE(y.empty());  // NOLINT(bugprone-use-after-move)
+        }
+
+        {  // Move assign empty buf to non-empty buf
+            Buffer x{b1};
+            Buffer y;
+
+            x = std::move(y);
+            EXPECT_TRUE(sane(x));
+            EXPECT_TRUE(x.empty());
+            EXPECT_TRUE(sane(y));    // NOLINT(bugprone-use-after-move)
+            EXPECT_TRUE(y.empty());  // NOLINT(bugprone-use-after-move)
+        }
+
+        {  // Move assign non-empty buf to non-empty buf
+            Buffer x{b1};
+            Buffer y{b2};
+            Buffer z{b3};
+
+            x = std::move(y);
+            EXPECT_TRUE(sane(x));
+            EXPECT_FALSE(x.empty());
+            EXPECT_TRUE(sane(y));    // NOLINT(bugprone-use-after-move)
+            EXPECT_TRUE(y.empty());  // NOLINT(bugprone-use-after-move)
+
+            x = std::move(z);
+            EXPECT_TRUE(sane(x));
+            EXPECT_FALSE(x.empty());
+            EXPECT_TRUE(sane(z));    // NOLINT(bugprone-use-after-move)
+            EXPECT_TRUE(z.empty());  // NOLINT(bugprone-use-after-move)
+        }
+    }
+
+    {
+        Buffer w{static_cast<Slice>(b0)};
+        EXPECT_TRUE(sane(w));
+        EXPECT_EQ(w, b0);
+
+        Buffer x{static_cast<Slice>(b1)};
+        EXPECT_TRUE(sane(x));
+        EXPECT_EQ(x, b1);
+
+        Buffer y{static_cast<Slice>(b2)};
+        EXPECT_TRUE(sane(y));
+        EXPECT_EQ(y, b2);
+
+        Buffer z{static_cast<Slice>(b3)};
+        EXPECT_TRUE(sane(z));
+        EXPECT_EQ(z, b3);
+
+        // Assign empty slice to empty buffer
+        w = static_cast<Slice>(b0);
+        EXPECT_TRUE(sane(w));
+        EXPECT_EQ(w, b0);
+
+        // Assign non-empty slice to empty buffer
+        w = static_cast<Slice>(b1);
+        EXPECT_TRUE(sane(w));
+        EXPECT_EQ(w, b1);
+
+        // Assign non-empty slice to non-empty buffer
+        x = static_cast<Slice>(b2);
+        EXPECT_TRUE(sane(x));
+        EXPECT_EQ(x, b2);
+
+        // Assign non-empty slice to non-empty buffer
+        y = static_cast<Slice>(z);
+        EXPECT_TRUE(sane(y));
+        EXPECT_EQ(y, z);
+
+        // Assign empty slice to non-empty buffer:
+        z = static_cast<Slice>(b0);
+        EXPECT_TRUE(sane(z));
+        EXPECT_EQ(z, b0);
+    }
+
+    {
+        auto test = [](Buffer const& b, std::size_t i) {
+            Buffer x{b};
+
+            // Try to allocate some number of bytes, possibly
+            // zero (which means clear) and sanity check
+            x(i);
+            EXPECT_TRUE(sane(x));
+            EXPECT_EQ(x.size(), i);
+            EXPECT_EQ((x.data() == nullptr), (i == 0));
+
+            // Try to allocate some more data (always non-zero)
+            x(i + 1);
+            EXPECT_TRUE(sane(x));
+            EXPECT_EQ(x.size(), i + 1);
+            EXPECT_NE(x.data(), nullptr);
+
+            // Try to clear:
+            x.clear();
+            EXPECT_TRUE(sane(x));
+            EXPECT_TRUE(x.empty());
+            EXPECT_EQ(x.data(), nullptr);
+
+            // Try to clear again:
+            x.clear();
+            EXPECT_TRUE(sane(x));
+            EXPECT_TRUE(x.empty());
+            EXPECT_EQ(x.data(), nullptr);
+        };
+
+        for (std::size_t i = 0; i < 16; ++i)
+        {
+            test(b0, i);
+            test(b1, i);
+        }
+    }
+}
+
+}  // namespace xrpl::test

src/tests/libxrpl/basics/FileUtilities.cpp

@@ -0,0 +1,94 @@
+#include <xrpl/basics/FileUtilities.h>
+
+#include <xrpl/basics/ByteUtilities.h>
+
+#include <boost/filesystem/operations.hpp>
+#include <boost/filesystem/path.hpp>
+#include <boost/system/detail/errc.hpp>
+#include <boost/system/detail/error_code.hpp>
+
+#include <gtest/gtest.h>
+
+#include <fstream>
+#include <stdexcept>
+#include <string>
+
+namespace xrpl {
+
+namespace {
+
+class TempFile
+{
+public:
+    explicit TempFile(boost::filesystem::path file, std::string const& contents)
+        : dir_(
+              boost::filesystem::temp_directory_path() /
+              boost::filesystem::unique_path("xrpl-file-utilities-%%%%-%%%%-%%%%"))
+        , file_(dir_ / file)
+    {
+        boost::filesystem::create_directory(dir_);
+
+        std::ofstream output(file_.string());
+        if (!output)
+            throw std::runtime_error("Unable to create temporary test file");
+
+        output << contents;
+    }
+
+    ~TempFile()
+    {
+        boost::system::error_code ec;
+        boost::filesystem::remove(file_, ec);
+        boost::filesystem::remove(dir_, ec);
+    }
+
+    [[nodiscard]] boost::filesystem::path const&
+    file() const
+    {
+        return file_;
+    }
+
+private:
+    boost::filesystem::path dir_;
+    boost::filesystem::path file_;
+};
+
+}  // namespace
+
+TEST(FileUtilitiesTest, get_file_contents)
+{
+    using namespace boost::system;
+
+    constexpr char const* kExpectedContents = "This file is very short. That's all we need.";
+
+    TempFile const file("test_file", "This is temporary text that should get overwritten");
+
+    error_code ec;
+    auto const path = file.file();
+
+    writeFileContents(ec, path, kExpectedContents);
+    EXPECT_FALSE(ec);
+
+    {
+        // Test with no max
+        auto const good = getFileContents(ec, path);
+        EXPECT_FALSE(ec);
+        EXPECT_EQ(good, kExpectedContents);
+    }
+
+    {
+        // Test with large max
+        auto const good = getFileContents(ec, path, kilobytes(1));
+        EXPECT_FALSE(ec);
+        EXPECT_EQ(good, kExpectedContents);
+    }
+
+    {
+        // Test with small max
+        auto const bad = getFileContents(ec, path, 16);
+        EXPECT_TRUE(ec && ec.value() == boost::system::errc::file_too_large);
+        EXPECT_TRUE(bad.empty());
+    }
+}
+
+}  // namespace xrpl

src/tests/libxrpl/basics/IOUAmount.cpp

@@ -0,0 +1,243 @@
+#include <xrpl/protocol/IOUAmount.h>
+
+#include <xrpl/basics/Number.h>
+#include <xrpl/beast/utility/Zero.h>
+
+#include <gtest/gtest.h>
+
+#include <cstdint>
+#include <limits>
+#include <sstream>
+#include <string>
+
+namespace xrpl {
+
+TEST(IOUAmountTest, zero)
+{
+    IOUAmount const z(0, 0);
+
+    EXPECT_EQ(z.mantissa(), 0);
+    EXPECT_EQ(z.exponent(), -100);
+    EXPECT_FALSE(z);
+    EXPECT_EQ(z.signum(), 0);
+    EXPECT_EQ(z, beast::kZero);
+
+    EXPECT_EQ((z + z), z);
+    EXPECT_EQ((z - z), z);
+    EXPECT_EQ(z, -z);
+
+    IOUAmount const zz(beast::kZero);
+    EXPECT_EQ(z, zz);
+
+    // https://github.com/XRPLF/rippled/issues/5170
+    IOUAmount const zzz{};
+    EXPECT_EQ(zzz, beast::kZero);
+    // EXPECT_EQ(zzz, zz);
+}
+
+TEST(IOUAmountTest, sig_num)
+{
+    IOUAmount const neg(-1, 0);
+    EXPECT_LT(neg.signum(), 0);
+
+    IOUAmount const zer(0, 0);
+    EXPECT_EQ(zer.signum(), 0);
+
+    IOUAmount const pos(1, 0);
+    EXPECT_GT(pos.signum(), 0);
+}
+
+TEST(IOUAmountTest, beast_zero)
+{
+    using beast::kZero;
+
+    {
+        IOUAmount const z(kZero);
+        EXPECT_TRUE(z == kZero);
+        EXPECT_TRUE(z >= kZero);
+        EXPECT_TRUE(z <= kZero);
+        EXPECT_FALSE(z != kZero);
+        EXPECT_FALSE(z > kZero);
+        EXPECT_FALSE(z < kZero);
+    }
+
+    {
+        IOUAmount const neg(-2, 0);
+        EXPECT_TRUE(neg < kZero);
+        EXPECT_TRUE(neg <= kZero);
+        EXPECT_TRUE(neg != kZero);
+        EXPECT_FALSE(neg == kZero);
+    }
+
+    {
+        IOUAmount const pos(2, 0);
+        EXPECT_TRUE(pos > kZero);
+        EXPECT_TRUE(pos >= kZero);
+        EXPECT_TRUE(pos != kZero);
+        EXPECT_FALSE(pos == kZero);
+    }
+}
+
+TEST(IOUAmountTest, comparisons)
+{
+    IOUAmount const n(-2, 0);
+    IOUAmount const z(0, 0);
+    IOUAmount const p(2, 0);
+    // For code readability, we want to use general
+    // EXPECT_TRUE instead of specific EXPECT_EQ etc.
+    EXPECT_TRUE(z == z);
+    EXPECT_TRUE(z >= z);
+    EXPECT_TRUE(z <= z);
+    EXPECT_TRUE(z == -z);
+    // NOLINTBEGIN(misc-redundant-expression)
+    EXPECT_FALSE(z > z);
+    EXPECT_FALSE(z < z);
+    EXPECT_FALSE(z != z);
+    // NOLINTEND(misc-redundant-expression)
+    EXPECT_FALSE(z != -z);
+
+    EXPECT_TRUE(n < z);
+    EXPECT_TRUE(n <= z);
+    EXPECT_TRUE(n != z);
+    EXPECT_FALSE(n > z);
+    EXPECT_FALSE(n >= z);
+    EXPECT_FALSE(n == z);
+
+    EXPECT_TRUE(p > z);
+    EXPECT_TRUE(p >= z);
+    EXPECT_TRUE(p != z);
+    EXPECT_FALSE(p < z);
+    EXPECT_FALSE(p <= z);
+    EXPECT_FALSE(p == z);
+
+    EXPECT_TRUE(n < p);
+    EXPECT_TRUE(n <= p);
+    EXPECT_TRUE(n != p);
+    EXPECT_FALSE(n > p);
+    EXPECT_FALSE(n >= p);
+    EXPECT_FALSE(n == p);
+
+    EXPECT_TRUE(p > n);
+    EXPECT_TRUE(p >= n);
+    EXPECT_TRUE(p != n);
+    EXPECT_FALSE(p < n);
+    EXPECT_FALSE(p <= n);
+    EXPECT_FALSE(p == n);
+
+    EXPECT_TRUE(p > -p);
+    EXPECT_TRUE(p >= -p);
+    EXPECT_TRUE(p != -p);
+
+    EXPECT_TRUE(n < -n);
+    EXPECT_TRUE(n <= -n);
+    EXPECT_TRUE(n != -n);
+}
+
+TEST(IOUAmountTest, to_string)
+{
+    auto test = [](IOUAmount const& n, std::string const& expected) {
+        auto const result = to_string(n);
+        std::stringstream ss;
+        ss << "to_string(" << result << "). Expected: " << expected;
+        EXPECT_EQ(result, expected) << ss.str();
+    };
+
+    for (auto const mantissaSize : MantissaRange::getAllScales())
+    {
+        NumberMantissaScaleGuard const mg(mantissaSize);
+
+        test(IOUAmount(-2, 0), "-2");
+        test(IOUAmount(0, 0), "0");
+        test(IOUAmount(2, 0), "2");
+        test(IOUAmount(25, -3), "0.025");
+        test(IOUAmount(-25, -3), "-0.025");
+        test(IOUAmount(25, 1), "250");
+        test(IOUAmount(-25, 1), "-250");
+        test(IOUAmount(2, 20), "2e20");
+        test(IOUAmount(-2, -20), "-2e-20");
+    }
+}
+
+TEST(IOUAmountTest, mul_ratio)
+{
+    /* The range for the mantissa when normalized */
+    constexpr std::int64_t kMinMantissa = 1000000000000000ull;
+    constexpr std::int64_t kMaxMantissa = 9999999999999999ull;
+    // log(2,maxMantissa) ~ 53.15
+    /* The range for the exponent when normalized */
+    constexpr int kMinExponent = -96;
+    constexpr int kMaxExponent = 80;
+    constexpr auto kMaxUInt = std::numeric_limits<std::uint32_t>::max();
+
+    {
+        // multiply by a number that would overflow the mantissa, then
+        // divide by the same number, and check we didn't lose any value
+        IOUAmount const bigMan(kMaxMantissa, 0);
+        EXPECT_EQ(bigMan, mulRatio(bigMan, kMaxUInt, kMaxUInt, true));
+        // rounding mode shouldn't matter as the result is exact
+        EXPECT_EQ(bigMan, mulRatio(bigMan, kMaxUInt, kMaxUInt, false));
+    }
+    {
+        // Similar test as above, but for negative values
+        IOUAmount const bigMan(-kMaxMantissa, 0);
+        EXPECT_EQ(bigMan, mulRatio(bigMan, kMaxUInt, kMaxUInt, true));
+        // rounding mode shouldn't matter as the result is exact
+        EXPECT_EQ(bigMan, mulRatio(bigMan, kMaxUInt, kMaxUInt, false));
+    }
+
+    {
+        // small amounts
+        IOUAmount const tiny(kMinMantissa, kMinExponent);
+        // Round up should give the smallest allowable number
+        EXPECT_EQ(tiny, mulRatio(tiny, 1, kMaxUInt, true));
+        EXPECT_EQ(tiny, mulRatio(tiny, kMaxUInt - 1, kMaxUInt, true));
+        // rounding down should be zero
+        EXPECT_EQ(beast::kZero, mulRatio(tiny, 1, kMaxUInt, false));
+        EXPECT_EQ(beast::kZero, mulRatio(tiny, kMaxUInt - 1, kMaxUInt, false));
+
+        // tiny negative numbers
+        IOUAmount const tinyNeg(-kMinMantissa, kMinExponent);
+        // Round up should give zero
+        EXPECT_EQ(beast::kZero, mulRatio(tinyNeg, 1, kMaxUInt, true));
+        EXPECT_EQ(beast::kZero, mulRatio(tinyNeg, kMaxUInt - 1, kMaxUInt, true));
+        // rounding down should be tiny
+        EXPECT_EQ(tinyNeg, mulRatio(tinyNeg, 1, kMaxUInt, false));
+        EXPECT_EQ(tinyNeg, mulRatio(tinyNeg, kMaxUInt - 1, kMaxUInt, false));
+    }
+
+    {  // rounding
+        {
+            IOUAmount const one(1, 0);
+            auto const rup = mulRatio(one, kMaxUInt - 1, kMaxUInt, true);
+            auto const rdown = mulRatio(one, kMaxUInt - 1, kMaxUInt, false);
+            EXPECT_EQ(rup.mantissa() - rdown.mantissa(), 1);
+        }
+        {
+            IOUAmount const big(kMaxMantissa, kMaxExponent);
+            auto const rup = mulRatio(big, kMaxUInt - 1, kMaxUInt, true);
+            auto const rdown = mulRatio(big, kMaxUInt - 1, kMaxUInt, false);
+            EXPECT_EQ(rup.mantissa() - rdown.mantissa(), 1);
+        }
+
+        {
+            IOUAmount const negOne(-1, 0);
+            auto const rup = mulRatio(negOne, kMaxUInt - 1, kMaxUInt, true);
+            auto const rdown = mulRatio(negOne, kMaxUInt - 1, kMaxUInt, false);
+            EXPECT_EQ(rup.mantissa() - rdown.mantissa(), 1);
+        }
+    }
+
+    {
+        // division by zero
+        IOUAmount const one(1, 0);
+        EXPECT_ANY_THROW({ mulRatio(one, 1, 0, true); });
+    }
+
+    {
+        // overflow
+        IOUAmount const big(kMaxMantissa, kMaxExponent);
+        EXPECT_ANY_THROW({ mulRatio(big, 2, 0, true); });
+    }
+}
+
+}  // namespace xrpl

src/tests/libxrpl/basics/IntrusiveShared.cpp

@@ -0,0 +1,844 @@
+#include <xrpl/basics/IntrusivePointer.h>    // IWYU pragma: keep
+#include <xrpl/basics/IntrusivePointer.ipp>  // IWYU pragma: keep
+#include <xrpl/basics/IntrusiveRefCounts.h>
+
+#include <gtest/gtest.h>
+
+#include <algorithm>
+#include <array>
+#include <atomic>
+#include <chrono>  // IWYU pragma: keep
+#include <condition_variable>
+#include <cstddef>
+#include <cstdint>
+#include <functional>
+#include <latch>
+#include <mutex>
+#include <optional>
+#include <random>
+#include <stdexcept>
+#include <thread>
+#include <utility>
+#include <variant>
+#include <vector>
+
+namespace xrpl::tests {
+
+/*
+ * Experimentally, we discovered that using std::barrier performs extremely
+ * poorly (~1 hour vs ~1 minute to run the test suite) in certain macOS
+ * environments. To unblock our macOS CI pipeline, we replaced std::barrier with a
+ * custom mutex-based barrier (Barrier) that significantly improves performance
+ * without compromising correctness. For future reference, if we ever consider
+ * reintroducing std::barrier, the following configuration is known to exhibit the
+ * problem:
+ *
+ *     Model Name: Mac mini
+ *     Model Identifier: Mac14,3
+ *     Model Number: Z16K000R4LL/A
+ *     Chip: Apple M2
+ *     Total Number of Cores: 8 (4 performance and 4 efficiency)
+ *     Memory: 24 GB
+ *     System Firmware Version: 11881.41.5
+ *     OS Loader Version: 11881.1.1
+ *     Apple clang version 16.0.0 (clang-1600.0.26.3)
+ *     Target: arm64-apple-darwin24.0.0
+ *     Thread model: posix
+ *
+ */
+struct Barrier
+{
+    std::mutex mtx;
+    std::condition_variable cv;
+    int count;
+    int const initial;
+    std::size_t generation{0};
+
+    explicit Barrier(int n) : count(n), initial(n)
+    {
+    }
+
+    void
+    arriveAndWait()
+    {
+        std::unique_lock lock(mtx);
+        auto const currentGeneration = generation;
+        if (--count == 0)
+        {
+            ++generation;
+            count = initial;
+            cv.notify_all();
+        }
+        else
+        {
+            cv.wait(lock, [&] { return generation != currentGeneration; });
+        }
+    }
+};
+
+namespace {
+enum class TrackedState : std::uint8_t {
+    Uninitialized,
+    Alive,
+    PartiallyDeletedStarted,
+    PartiallyDeleted,
+    DeletedStarted,
+    Deleted
+};
+
+class TIBase : public IntrusiveRefCounts
+{
+public:
+    static constexpr std::size_t kMaxStates = 128;
+    static std::array<std::atomic<TrackedState>, kMaxStates> state;
+    static std::atomic<std::size_t> nextId;
+    static TrackedState
+    getState(std::size_t id)
+    {
+        if (id >= state.size())
+            throw std::out_of_range("TIBase state id out of range");
+
+        return state[id].load(std::memory_order_acquire);
+    }
+    static void
+    resetStates(bool resetCallback)
+    {
+        for (std::size_t i = 0; i < kMaxStates; ++i)
+        {
+            state[i].store(TrackedState::Uninitialized, std::memory_order_release);
+        }
+        nextId.store(0, std::memory_order_release);
+        if (resetCallback)
+            TIBase::tracingCallback = [](TrackedState, std::optional<TrackedState>) {};
+    }
+
+    struct ResetStatesGuard
+    {
+        bool resetCallback{false};
+
+        ResetStatesGuard(bool resetCallback) : resetCallback{resetCallback}
+        {
+            TIBase::resetStates(resetCallback);
+        }
+        ~ResetStatesGuard()
+        {
+            TIBase::resetStates(resetCallback);
+        }
+    };
+
+    TIBase() : id{checkoutID()}
+    {
+        state[id].store(TrackedState::Alive, std::memory_order_relaxed);
+    }
+    ~TIBase() override
+    {
+        using enum TrackedState;
+
+        tracingCallback(state[id].load(std::memory_order_relaxed), DeletedStarted);
+
+        // Use relaxed memory order to try to avoid atomic operations from
+        // adding additional memory synchronizations that may hide threading
+        // errors in the underlying shared pointer class.
+        state[id].store(DeletedStarted, std::memory_order_relaxed);
+
+        tracingCallback(DeletedStarted, Deleted);
+
+        state[id].store(TrackedState::Deleted, std::memory_order_relaxed);
+
+        tracingCallback(TrackedState::Deleted, std::nullopt);
+    }
+
+    void
+    partialDestructor() const
+    {
+        using enum TrackedState;
+
+        tracingCallback(state[id].load(std::memory_order_relaxed), PartiallyDeletedStarted);
+
+        state[id].store(PartiallyDeletedStarted, std::memory_order_relaxed);
+
+        tracingCallback(PartiallyDeletedStarted, PartiallyDeleted);
+
+        state[id].store(PartiallyDeleted, std::memory_order_relaxed);
+
+        tracingCallback(PartiallyDeleted, std::nullopt);
+    }
+
+    static std::function<void(TrackedState, std::optional<TrackedState>)> tracingCallback;
+
+    std::size_t const id;
+
+private:
+    static std::size_t
+    checkoutID()
+    {
+        auto const id = nextId.fetch_add(1, std::memory_order_acq_rel);
+        if (id >= state.size())
+            throw std::out_of_range("TIBase state capacity exceeded");
+
+        return id;
+    }
+};
+
+std::array<std::atomic<TrackedState>, TIBase::kMaxStates> TIBase::state;
+std::atomic<std::size_t> TIBase::nextId{0};
+
+std::function<void(TrackedState, std::optional<TrackedState>)> TIBase::tracingCallback =
+    [](TrackedState, std::optional<TrackedState>) {};
+
+}  // namespace
+
+TEST(IntrusiveSharedTest, basics)
+{
+    {
+        TIBase::ResetStatesGuard const rsg{true};
+
+        TIBase const b;
+        EXPECT_EQ(b.useCount(), 1);
+        b.addWeakRef();
+        EXPECT_EQ(b.useCount(), 1);
+        auto s = b.releaseStrongRef();
+        EXPECT_EQ(s, ReleaseStrongRefAction::PartialDestroy);
+        EXPECT_EQ(b.useCount(), 0);
+        TIBase const* pb = &b;
+        partialDestructorFinished(&pb);
+        EXPECT_FALSE(pb);
+        auto w = b.releaseWeakRef();
+        EXPECT_EQ(w, ReleaseWeakRefAction::Destroy);
+    }
+
+    std::vector<SharedIntrusive<TIBase>> strong;
+    std::vector<WeakIntrusive<TIBase>> weak;
+    {
+        TIBase::ResetStatesGuard const rsg{true};
+
+        using enum TrackedState;
+        auto b = makeSharedIntrusive<TIBase>();
+        auto id = b->id;
+        EXPECT_EQ(TIBase::getState(id), Alive);
+        EXPECT_EQ(b->useCount(), 1);
+        for (int i = 0; i < 10; ++i)
+        {
+            strong.push_back(b);
+        }
+        b.reset();
+        EXPECT_EQ(TIBase::getState(id), Alive);
+        strong.resize(strong.size() - 1);
+        EXPECT_EQ(TIBase::getState(id), Alive);
+        strong.clear();
+        EXPECT_EQ(TIBase::getState(id), Deleted);
+
+        b = makeSharedIntrusive<TIBase>();
+        id = b->id;
+        EXPECT_EQ(TIBase::getState(id), Alive);
+        EXPECT_EQ(b->useCount(), 1);
+        for (int i = 0; i < 10; ++i)
+        {
+            weak.emplace_back(b);
+            EXPECT_EQ(b->useCount(), 1);
+        }
+        EXPECT_EQ(TIBase::getState(id), Alive);
+        weak.resize(weak.size() - 1);
+        EXPECT_EQ(TIBase::getState(id), Alive);
+        b.reset();
+        EXPECT_EQ(TIBase::getState(id), PartiallyDeleted);
+        while (!weak.empty())
+        {
+            weak.resize(weak.size() - 1);
+            if (!weak.empty())
+            {
+                EXPECT_EQ(TIBase::getState(id), PartiallyDeleted);
+            }
+        }
+        EXPECT_EQ(TIBase::getState(id), Deleted);
+    }
+    {
+        TIBase::ResetStatesGuard const rsg{true};
+
+        using enum TrackedState;
+        auto b = makeSharedIntrusive<TIBase>();
+        auto id = b->id;
+        EXPECT_EQ(TIBase::getState(id), Alive);
+        WeakIntrusive<TIBase> w{b};
+        EXPECT_EQ(TIBase::getState(id), Alive);
+        auto s = w.lock();
+        EXPECT_TRUE(s && s->useCount() == 2);
+        b.reset();
+        EXPECT_TRUE(TIBase::getState(id) == Alive);
+        EXPECT_TRUE(s && s->useCount() == 1);
+        s.reset();
+        EXPECT_EQ(TIBase::getState(id), PartiallyDeleted);
+        EXPECT_TRUE(w.expired());
+        s = w.lock();
+        // Cannot convert a weak pointer to a strong pointer if object is
+        // already partially deleted
+        EXPECT_FALSE(s);
+        w.reset();
+        EXPECT_EQ(TIBase::getState(id), Deleted);
+    }
+    {
+        TIBase::ResetStatesGuard const rsg{true};
+
+        using enum TrackedState;
+        using swu = SharedWeakUnion<TIBase>;
+        swu b = makeSharedIntrusive<TIBase>();
+        EXPECT_TRUE(b.isStrong() && b.useCount() == 1);
+        auto id = b.get()->id;
+        EXPECT_EQ(TIBase::getState(id), Alive);
+        swu w = b;
+        EXPECT_TRUE(TIBase::getState(id) == Alive);
+        EXPECT_TRUE(w.isStrong() && b.useCount() == 2);
+        w.convertToWeak();
+        EXPECT_TRUE(w.isWeak() && b.useCount() == 1);
+        swu s = w;
+        EXPECT_TRUE(s.isWeak() && b.useCount() == 1);
+        s.convertToStrong();
+        EXPECT_TRUE(s.isStrong() && b.useCount() == 2);
+        b.reset();
+        EXPECT_EQ(TIBase::getState(id), Alive);
+        EXPECT_EQ(s.useCount(), 1);
+        EXPECT_FALSE(w.expired());
+        s.reset();
+        EXPECT_EQ(TIBase::getState(id), PartiallyDeleted);
+        EXPECT_TRUE(w.expired());
+        w.convertToStrong();
+        // Cannot convert a weak pointer to a strong pointer if object is
+        // already partially deleted
+        EXPECT_TRUE(w.isWeak());
+        w.reset();
+        EXPECT_EQ(TIBase::getState(id), Deleted);
+    }
+    {
+        // Testing SharedWeakUnion assignment operator
+
+        TIBase::ResetStatesGuard const rsg{true};
+
+        auto strong1 = makeSharedIntrusive<TIBase>();
+        auto strong2 = makeSharedIntrusive<TIBase>();
+
+        auto id1 = strong1->id;
+        auto id2 = strong2->id;
+
+        EXPECT_NE(id1, id2);
+
+        SharedWeakUnion<TIBase> union1 = strong1;
+        SharedWeakUnion<TIBase> union2 = strong2;
+
+        EXPECT_TRUE(union1.isStrong());
+        EXPECT_TRUE(union2.isStrong());
+        EXPECT_EQ(union1.get(), strong1.get());
+        EXPECT_EQ(union2.get(), strong2.get());
+
+        // 1) Normal assignment: explicitly calls SharedWeakUnion assignment
+        union1 = union2;
+        EXPECT_TRUE(union1.isStrong());
+        EXPECT_TRUE(union2.isStrong());
+        EXPECT_EQ(union1.get(), union2.get());
+        EXPECT_EQ(TIBase::getState(id1), TrackedState::Alive);
+        EXPECT_EQ(TIBase::getState(id2), TrackedState::Alive);
+
+        // 2) Test self-assignment
+        EXPECT_TRUE(union1.isStrong());
+        EXPECT_EQ(TIBase::getState(id1), TrackedState::Alive);
+        int const initialRefCount = strong1->useCount();
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wself-assign-overloaded"
+        union1 = union1;  // Self-assignment
+#pragma clang diagnostic pop
+        EXPECT_TRUE(union1.isStrong());
+        EXPECT_EQ(TIBase::getState(id1), TrackedState::Alive);
+        EXPECT_EQ(strong1->useCount(), initialRefCount);
+
+        // 3) Test assignment from null union pointer
+        union1 = SharedWeakUnion<TIBase>();
+        EXPECT_EQ(union1.get(), nullptr);
+
+        // 4) Test assignment to expired union pointer
+        strong2.reset();
+        union2.reset();
+        union1 = union2;
+        EXPECT_EQ(union1.get(), nullptr);
+        EXPECT_EQ(TIBase::getState(id2), TrackedState::Deleted);
+    }
+}
+
+TEST(IntrusiveSharedTest, partial_delete)
+{
+    // This test creates two threads. One with a strong pointer and one
+    // with a weak pointer. The strong pointer is reset while the weak
+    // pointer still holds a reference, triggering a partial delete.
+    // While the partial delete function runs (a sleep is inserted) the
+    // weak pointer is reset. The destructor should wait to run until
+    // after the partial delete function has completed running.
+
+    using enum TrackedState;
+
+    TIBase::ResetStatesGuard const rsg{true};
+
+    auto strong = makeSharedIntrusive<TIBase>();
+    WeakIntrusive<TIBase> weak{strong};
+    std::atomic<bool> destructorRan{false};
+    std::atomic<bool> partialDeleteRan{false};
+    std::latch partialDeleteStartedSyncPoint{2};
+    strong->tracingCallback = [&](TrackedState cur, std::optional<TrackedState> next) {
+        using enum TrackedState;
+        if (next == DeletedStarted)
+        {
+            // strong goes out of scope while weak is still in scope
+            // This checks that partialDelete has run to completion
+            // before the destructor is called. A sleep is inserted
+            // inside the partial delete to make sure the destructor is
+            // given an opportunity to run during partial delete.
+            EXPECT_EQ(cur, PartiallyDeleted);
+        }
+        if (next == PartiallyDeletedStarted)
+        {
+            partialDeleteStartedSyncPoint.arrive_and_wait();
+            using namespace std::chrono_literals;
+            // Sleep and let the weak pointer go out of scope,
+            // potentially triggering a destructor while partial delete
+            // is running. The test is to make sure that doesn't happen.
+            std::this_thread::sleep_for(800ms);
+        }
+        if (next == PartiallyDeleted)
+        {
+            EXPECT_FALSE(partialDeleteRan.exchange(true) || destructorRan.load());
+        }
+        if (next == Deleted)
+        {
+            EXPECT_FALSE(destructorRan.exchange(true));
+        }
+    };
+    std::thread t1{[&] {
+        partialDeleteStartedSyncPoint.arrive_and_wait();
+        weak.reset();  // Trigger a full delete as soon as the partial
+                       // delete starts
+    }};
+    std::thread t2{[&] {
+        strong.reset();  // Trigger a partial delete
+    }};
+    t1.join();
+    t2.join();
+
+    EXPECT_TRUE(destructorRan.load() && partialDeleteRan.load());
+}
+
+TEST(IntrusiveSharedTest, destructor)
+{
+    // This test creates two threads. One with a strong pointer and one
+    // with a weak pointer. The weak pointer is reset while the strong
+    // pointer still holds a reference. Then the strong pointer is
+    // reset. Only the destructor should run. The partial destructor
+    // should not be called. Since the weak reset runs to completion
+    // before the strong pointer is reset, threading doesn't add much to
+    // this test, but there is no harm in keeping it.
+
+    using enum TrackedState;
+
+    TIBase::ResetStatesGuard const rsg{true};
+
+    auto strong = makeSharedIntrusive<TIBase>();
+    WeakIntrusive<TIBase> weak{strong};
+    std::atomic<bool> destructorRan{false};
+    std::atomic<bool> partialDeleteRan{false};
+    std::latch weakResetSyncPoint{2};
+    strong->tracingCallback = [&](TrackedState cur, std::optional<TrackedState> next) {
+        using enum TrackedState;
+        if (next == PartiallyDeleted)
+        {
+            EXPECT_FALSE(partialDeleteRan.exchange(true) || destructorRan.load());
+        }
+        if (next == Deleted)
+        {
+            EXPECT_FALSE(destructorRan.exchange(true));
+        }
+    };
+    std::thread t1{[&] {
+        weak.reset();
+        weakResetSyncPoint.arrive_and_wait();
+    }};
+    std::thread t2{[&] {
+        weakResetSyncPoint.arrive_and_wait();
+        strong.reset();  // Trigger a partial delete
+    }};
+    t1.join();
+    t2.join();
+
+    EXPECT_TRUE(destructorRan.load() && !partialDeleteRan.load());
+}
+
+TEST(IntrusiveSharedTest, multithreaded_clear_mixed_variant)
+{
+    // This test creates and destroys many strong and weak pointers in a
+    // loop. There is a random mix of strong and weak pointers stored in
+    // a vector (held as a variant). Both threads clear all the pointers
+    // and check that the invariants hold.
+
+    using enum TrackedState;
+    TIBase::ResetStatesGuard const rsg{true};
+
+    std::atomic<int> destructionState{0};
+    // returns destructorRan and partialDestructorRan (in that order)
+    auto getDestructorState = [&]() -> std::pair<bool, bool> {
+        int const s = destructionState.load(std::memory_order_relaxed);
+        return {(s & 1) != 0, (s & 2) != 0};
+    };
+    auto setDestructorRan = [&]() -> void {
+        destructionState.fetch_or(1, std::memory_order_acq_rel);
+    };
+    auto setPartialDeleteRan = [&]() -> void {
+        destructionState.fetch_or(2, std::memory_order_acq_rel);
+    };
+    auto tracingCallback = [&](TrackedState cur, std::optional<TrackedState> next) {
+        using enum TrackedState;
+        auto [destructorRan, partialDeleteRan] = getDestructorState();
+        if (next == PartiallyDeleted)
+        {
+            EXPECT_FALSE(partialDeleteRan || destructorRan);
+            setPartialDeleteRan();
+        }
+        if (next == Deleted)
+        {
+            EXPECT_FALSE(destructorRan);
+            setDestructorRan();
+        }
+    };
+    auto createVecOfPointers = [&](auto const& toClone, std::default_random_engine& eng)
+        -> std::vector<std::variant<SharedIntrusive<TIBase>, WeakIntrusive<TIBase>>> {
+        std::vector<std::variant<SharedIntrusive<TIBase>, WeakIntrusive<TIBase>>> result;
+        std::uniform_int_distribution<> toCreateDist(4, 64);
+        std::uniform_int_distribution<> isStrongDist(0, 1);
+        auto numToCreate = toCreateDist(eng);
+        result.reserve(numToCreate);
+        for (int i = 0; i < numToCreate; ++i)
+        {
+            if (isStrongDist(eng))
+            {
+                result.emplace_back(SharedIntrusive<TIBase>(toClone));
+            }
+            else
+            {
+                result.emplace_back(WeakIntrusive<TIBase>(toClone));
+            }
+        }
+        return result;
+    };
+    constexpr int kLoopIters = 2 * 1024;
+    constexpr int kNumThreads = 16;
+    std::vector<SharedIntrusive<TIBase>> toClone;
+    Barrier loopStartSyncPoint{kNumThreads};
+    Barrier postCreateToCloneSyncPoint{kNumThreads};
+    Barrier postCreateVecOfPointersSyncPoint{kNumThreads};
+    auto engines = [&]() -> std::vector<std::default_random_engine> {
+        std::random_device rd;
+        std::vector<std::default_random_engine> result;
+        result.reserve(kNumThreads);
+        for (int i = 0; i < kNumThreads; ++i)
+            result.emplace_back(rd());
+        return result;
+    }();
+
+    // cloneAndDestroy clones the strong pointer into a vector of mixed
+    // strong and weak pointers and destroys them all at once.
+    // threadId==0 is special.
+    auto cloneAndDestroy = [&](int threadId) {
+        for (int i = 0; i < kLoopIters; ++i)
+        {
+            // ------ Sync Point ------
+            loopStartSyncPoint.arriveAndWait();
+
+            // only thread 0 should reset the state
+            std::optional<TIBase::ResetStatesGuard> rsg;
+            if (threadId == 0)
+            {
+                // Thread 0 is the genesis thread. It creates the strong
+                // pointers to be cloned by the other threads. This
+                // thread will also check that the destructor ran and
+                // clear the temporary variables.
+
+                rsg.emplace(false);
+                auto [destructorRan, partialDeleteRan] = getDestructorState();
+                EXPECT_TRUE(i == 0 || destructorRan);
+                destructionState.store(0, std::memory_order_release);
+
+                toClone.clear();
+                toClone.resize(kNumThreads);
+                auto strong = makeSharedIntrusive<TIBase>();
+                strong->tracingCallback = tracingCallback;
+                std::ranges::fill(toClone, strong);
+            }
+
+            // ------ Sync Point ------
+            postCreateToCloneSyncPoint.arriveAndWait();
+
+            auto v = createVecOfPointers(toClone[threadId], engines[threadId]);
+            toClone[threadId].reset();
+
+            // ------ Sync Point ------
+            postCreateVecOfPointersSyncPoint.arriveAndWait();
+
+            v.clear();
+        }
+    };
+    std::vector<std::thread> threads;
+    threads.reserve(kNumThreads);
+    for (int i = 0; i < kNumThreads; ++i)
+    {
+        threads.emplace_back(cloneAndDestroy, i);
+    }
+    for (int i = 0; i < kNumThreads; ++i)
+    {
+        threads[i].join();
+    }
+}
+
+TEST(IntrusiveSharedTest, multithreaded_clear_mixed_union)
+{
+    // This test creates and destroys many SharedWeak pointers in a
+    // loop. All the pointers start as strong and a loop randomly
+    // convert them between strong and weak pointers. Both threads clear
+    // all the pointers and check that the invariants hold.
+    //
+    // Note: This test also differs from the test above in that the pointers
+    // randomly change from strong to weak and from weak to strong in a
+    // loop. This can't be done in the variant test above because variant is
+    // not thread safe while the SharedWeakUnion is thread safe.
+
+    using enum TrackedState;
+
+    TIBase::ResetStatesGuard const rsg{true};
+
+    std::atomic<int> destructionState{0};
+    // returns destructorRan and partialDestructorRan (in that order)
+    auto getDestructorState = [&]() -> std::pair<bool, bool> {
+        int const s = destructionState.load(std::memory_order_relaxed);
+        return {(s & 1) != 0, (s & 2) != 0};
+    };
+    auto setDestructorRan = [&]() -> void {
+        destructionState.fetch_or(1, std::memory_order_acq_rel);
+    };
+    auto setPartialDeleteRan = [&]() -> void {
+        destructionState.fetch_or(2, std::memory_order_acq_rel);
+    };
+    auto tracingCallback = [&](TrackedState cur, std::optional<TrackedState> next) {
+        using enum TrackedState;
+        auto [destructorRan, partialDeleteRan] = getDestructorState();
+        if (next == PartiallyDeleted)
+        {
+            EXPECT_FALSE(partialDeleteRan || destructorRan);
+            setPartialDeleteRan();
+        }
+        if (next == Deleted)
+        {
+            EXPECT_FALSE(destructorRan);
+            setDestructorRan();
+        }
+    };
+    auto createVecOfPointers =
+        [&](auto const& toClone,
+            std::default_random_engine& eng) -> std::vector<SharedWeakUnion<TIBase>> {
+        std::vector<SharedWeakUnion<TIBase>> result;
+        std::uniform_int_distribution<> toCreateDist(4, 64);
+        auto numToCreate = toCreateDist(eng);
+        result.reserve(numToCreate);
+        for (int i = 0; i < numToCreate; ++i)
+            result.emplace_back(SharedIntrusive<TIBase>(toClone));
+        return result;
+    };
+    constexpr int kLoopIters = 2 * 1024;
+    constexpr int kFlipPointersLoopIters = 256;
+    constexpr int kNumThreads = 16;
+    std::vector<SharedIntrusive<TIBase>> toClone;
+    Barrier loopStartSyncPoint{kNumThreads};
+    Barrier postCreateToCloneSyncPoint{kNumThreads};
+    Barrier postCreateVecOfPointersSyncPoint{kNumThreads};
+    Barrier postFlipPointersLoopSyncPoint{kNumThreads};
+    auto engines = [&]() -> std::vector<std::default_random_engine> {
+        std::random_device rd;
+        std::vector<std::default_random_engine> result;
+        result.reserve(kNumThreads);
+        for (int i = 0; i < kNumThreads; ++i)
+            result.emplace_back(rd());
+        return result;
+    }();
+
+    // cloneAndDestroy clones the strong pointer into a vector of
+    // mixed strong and weak pointers, runs a loop that randomly
+    // changes strong pointers to weak pointers,  and destroys them
+    // all at once.
+    auto cloneAndDestroy = [&](int threadId) {
+        for (int i = 0; i < kLoopIters; ++i)
+        {
+            // ------ Sync Point ------
+            loopStartSyncPoint.arriveAndWait();
+
+            // only thread 0 should reset the state
+            std::optional<TIBase::ResetStatesGuard> rsg;
+            if (threadId == 0)
+            {
+                // threadId 0 is the genesis thread. It creates the
+                // strong point to be cloned by the other threads. This
+                // thread will also check that the destructor ran and
+                // clear the temporary variables.
+                rsg.emplace(false);
+                auto [destructorRan, partialDeleteRan] = getDestructorState();
+                EXPECT_TRUE(i == 0 || destructorRan);
+                destructionState.store(0, std::memory_order_release);
+
+                toClone.clear();
+                toClone.resize(kNumThreads);
+                auto strong = makeSharedIntrusive<TIBase>();
+                strong->tracingCallback = tracingCallback;
+                std::ranges::fill(toClone, strong);
+            }
+
+            // ------ Sync Point ------
+            postCreateToCloneSyncPoint.arriveAndWait();
+
+            auto v = createVecOfPointers(toClone[threadId], engines[threadId]);
+            toClone[threadId].reset();
+
+            // ------ Sync Point ------
+            postCreateVecOfPointersSyncPoint.arriveAndWait();
+
+            std::uniform_int_distribution<> isStrongDist(0, 1);
+            for (int f = 0; f < kFlipPointersLoopIters; ++f)
+            {
+                for (auto& p : v)
+                {
+                    if (isStrongDist(engines[threadId]))
+                    {
+                        p.convertToStrong();
+                    }
+                    else
+                    {
+                        p.convertToWeak();
+                    }
+                }
+            }
+
+            // ------ Sync Point ------
+            postFlipPointersLoopSyncPoint.arriveAndWait();
+
+            v.clear();
+        }
+    };
+    std::vector<std::thread> threads;
+    threads.reserve(kNumThreads);
+    for (int i = 0; i < kNumThreads; ++i)
+    {
+        threads.emplace_back(cloneAndDestroy, i);
+    }
+    for (int i = 0; i < kNumThreads; ++i)
+    {
+        threads[i].join();
+    }
+}
+
+TEST(IntrusiveSharedTest, multithreaded_locking_weak)
+{
+    // This test creates a single shared atomic pointer that multiple thread
+    // create weak pointers from. The threads then lock the weak pointers.
+    // Both threads clear all the pointers and check that the invariants
+    // hold.
+
+    using enum TrackedState;
+
+    TIBase::ResetStatesGuard const rsg{true};
+
+    std::atomic<int> destructionState{0};
+    // returns destructorRan and partialDestructorRan (in that order)
+    auto getDestructorState = [&]() -> std::pair<bool, bool> {
+        int const s = destructionState.load(std::memory_order_relaxed);
+        return {(s & 1) != 0, (s & 2) != 0};
+    };
+    auto setDestructorRan = [&]() -> void {
+        destructionState.fetch_or(1, std::memory_order_acq_rel);
+    };
+    auto setPartialDeleteRan = [&]() -> void {
+        destructionState.fetch_or(2, std::memory_order_acq_rel);
+    };
+    auto tracingCallback = [&](TrackedState cur, std::optional<TrackedState> next) {
+        using enum TrackedState;
+        auto [destructorRan, partialDeleteRan] = getDestructorState();
+        if (next == PartiallyDeleted)
+        {
+            EXPECT_FALSE(partialDeleteRan || destructorRan);
+            setPartialDeleteRan();
+        }
+        if (next == Deleted)
+        {
+            EXPECT_FALSE(destructorRan);
+            setDestructorRan();
+        }
+    };
+
+    constexpr int kLoopIters = 2 * 1024;
+    constexpr int kLockWeakLoopIters = 256;
+    constexpr int kNumThreads = 16;
+    std::vector<SharedIntrusive<TIBase>> toLock;
+    Barrier loopStartSyncPoint{kNumThreads};
+    Barrier postCreateToLockSyncPoint{kNumThreads};
+    Barrier postLockWeakLoopSyncPoint{kNumThreads};
+
+    // lockAndDestroy creates weak pointers from the strong pointer
+    // and runs a loop that locks the weak pointer. At the end of the loop
+    // all the pointers are destroyed all at once.
+    auto lockAndDestroy = [&](int threadId) {
+        for (int i = 0; i < kLoopIters; ++i)
+        {
+            // ------ Sync Point ------
+            loopStartSyncPoint.arriveAndWait();
+
+            // only thread 0 should reset the state
+            std::optional<TIBase::ResetStatesGuard> rsg;
+            if (threadId == 0)
+            {
+                // threadId 0 is the genesis thread. It creates the
+                // strong point to be locked by the other threads. This
+                // thread will also check that the destructor ran and
+                // clear the temporary variables.
+                rsg.emplace(false);
+                auto [destructorRan, partialDeleteRan] = getDestructorState();
+                EXPECT_TRUE(i == 0 || destructorRan);
+                destructionState.store(0, std::memory_order_release);
+
+                toLock.clear();
+                toLock.resize(kNumThreads);
+                auto strong = makeSharedIntrusive<TIBase>();
+                strong->tracingCallback = tracingCallback;
+                std::ranges::fill(toLock, strong);
+            }
+
+            // ------ Sync Point ------
+            postCreateToLockSyncPoint.arriveAndWait();
+
+            // Multiple threads all create a weak pointer from the same
+            // strong pointer
+            WeakIntrusive const weak{toLock[threadId]};
+            for (int wi = 0; wi < kLockWeakLoopIters; ++wi)
+            {
+                EXPECT_FALSE(weak.expired());
+                auto strong = weak.lock();
+                EXPECT_TRUE(strong);
+            }
+
+            // ------ Sync Point ------
+            postLockWeakLoopSyncPoint.arriveAndWait();
+
+            toLock[threadId].reset();
+        }
+    };
+    std::vector<std::thread> threads;
+    threads.reserve(kNumThreads);
+    for (int i = 0; i < kNumThreads; ++i)
+    {
+        threads.emplace_back(lockAndDestroy, i);
+    }
+    for (int i = 0; i < kNumThreads; ++i)
+    {
+        threads[i].join();
+    }
+}
+
+}  // namespace xrpl::tests

src/tests/libxrpl/basics/KeyCache.cpp

@@ -0,0 +1,81 @@
+#include <xrpl/basics/TaggedCache.h>
+#include <xrpl/basics/TaggedCache.ipp>  // IWYU pragma: keep
+#include <xrpl/basics/chrono.h>
+#include <xrpl/beast/utility/Journal.h>
+#include <xrpl/protocol/Protocol.h>
+
+#include <gtest/gtest.h>
+#include <helpers/TestSink.h>
+
+#include <string>
+
+namespace xrpl {
+
+class KeyCacheTest : public ::testing::Test
+{
+public:
+};
+
+TEST_F(KeyCacheTest, key_cache)
+{
+    using namespace std::chrono_literals;
+    TestStopwatch clock;
+    clock.set(0);
+
+    using Key = std::string;
+    using Cache = TaggedCache<Key, int, true>;
+
+    beast::Journal const j{TestSink::instance()};
+
+    // Insert an item, retrieve it, and age it so it gets purged.
+    {
+        Cache c("test", LedgerIndex(1), 2s, clock, j);
+
+        EXPECT_EQ(c.size(), 0);
+        EXPECT_TRUE(c.insert("one"));
+        EXPECT_FALSE(c.insert("one"));
+        EXPECT_EQ(c.size(), 1);
+        EXPECT_TRUE(c.touchIfExists("one"));
+        ++clock;
+        c.sweep();
+        EXPECT_EQ(c.size(), 1);
+        ++clock;
+        c.sweep();
+        EXPECT_EQ(c.size(), 0);
+        EXPECT_FALSE(c.touchIfExists("one"));
+    }
+
+    // Insert two items, have one expire
+    {
+        Cache c("test", LedgerIndex(2), 2s, clock, j);
+
+        EXPECT_TRUE(c.insert("one"));
+        EXPECT_EQ(c.size(), 1);
+        EXPECT_TRUE(c.insert("two"));
+        EXPECT_EQ(c.size(), 2);
+        ++clock;
+        c.sweep();
+        EXPECT_EQ(c.size(), 2);
+        EXPECT_TRUE(c.touchIfExists("two"));
+        ++clock;
+        c.sweep();
+        EXPECT_EQ(c.size(), 1);
+    }
+
+    // Insert three items (1 over limit), sweep
+    {
+        Cache c("test", LedgerIndex(2), 3s, clock, j);
+
+        EXPECT_TRUE(c.insert("one"));
+        ++clock;
+        EXPECT_TRUE(c.insert("two"));
+        ++clock;
+        EXPECT_TRUE(c.insert("three"));
+        ++clock;
+        EXPECT_EQ(c.size(), 3);
+        c.sweep();
+        EXPECT_LT(c.size(), 3);
+    }
+}
+
+}  // namespace xrpl

src/tests/libxrpl/basics/StringUtilities.cpp

@@ -0,0 +1,293 @@
+#include <xrpl/basics/StringUtilities.h>
+
+#include <xrpl/basics/Slice.h>
+#include <xrpl/basics/ToString.h>
+
+#include <gtest/gtest.h>
+
+#include <string>
+
+namespace xrpl {
+
+class StringUtilitiesTest : public ::testing::Test
+{
+public:
+    static void
+    testUnHexSuccess(std::string const& strIn, std::string const& strExpected)
+    {
+        auto rv = strUnHex(strIn);
+        EXPECT_TRUE(rv);
+
+        // NOLINTNEXTLINE(bugprone-unchecked-optional-access)
+        EXPECT_EQ(makeSlice(*rv), makeSlice(strExpected));
+    }
+
+    static void
+    testUnHexFailure(std::string const& strIn)
+    {
+        auto rv = strUnHex(strIn);
+        EXPECT_FALSE(rv);
+    }
+};
+
+TEST_F(StringUtilitiesTest, un_hex)
+{
+    testUnHexSuccess("526970706c6544", "RippleD");
+    testUnHexSuccess("A", "\n");
+    testUnHexSuccess("0A", "\n");
+    testUnHexSuccess("D0A", "\r\n");
+    testUnHexSuccess("0D0A", "\r\n");
+    testUnHexSuccess("200D0A", " \r\n");
+    testUnHexSuccess("282A2B2C2D2E2F29", "(*+,-./)");
+
+    // Check for things which contain some or only invalid characters
+    testUnHexFailure("123X");
+    testUnHexFailure("V");
+    testUnHexFailure("XRP");
+}
+
+TEST_F(StringUtilitiesTest, parse_url)
+{
+    // Expected passes.
+    {
+        ParsedUrl pUrl;
+        EXPECT_TRUE(parseUrl(pUrl, "scheme://"));
+        EXPECT_EQ(pUrl.scheme, "scheme");
+        EXPECT_TRUE(pUrl.username.empty());
+        EXPECT_TRUE(pUrl.password.empty());
+        EXPECT_TRUE(pUrl.domain.empty());
+        EXPECT_FALSE(pUrl.port);
+        // RFC 3986:
+        // > In general, a URI that uses the generic syntax for authority
+        //   with an empty path should be normalized to a path of "/".
+        // Do we want to normalize paths?
+        EXPECT_TRUE(pUrl.path.empty());
+    }
+
+    {
+        ParsedUrl pUrl;
+        EXPECT_TRUE(parseUrl(pUrl, "scheme:///"));
+        EXPECT_EQ(pUrl.scheme, "scheme");
+        EXPECT_TRUE(pUrl.username.empty());
+        EXPECT_TRUE(pUrl.password.empty());
+        EXPECT_TRUE(pUrl.domain.empty());
+        EXPECT_FALSE(pUrl.port);
+        EXPECT_EQ(pUrl.path, "/");
+    }
+
+    {
+        ParsedUrl pUrl;
+        EXPECT_TRUE(parseUrl(pUrl, "lower://domain"));
+        EXPECT_EQ(pUrl.scheme, "lower");
+        EXPECT_TRUE(pUrl.username.empty());
+        EXPECT_TRUE(pUrl.password.empty());
+        EXPECT_EQ(pUrl.domain, "domain");
+        EXPECT_FALSE(pUrl.port);
+        EXPECT_TRUE(pUrl.path.empty());
+    }
+
+    {
+        ParsedUrl pUrl;
+        EXPECT_TRUE(parseUrl(pUrl, "UPPER://domain:234/"));
+        EXPECT_EQ(pUrl.scheme, "upper");
+        EXPECT_TRUE(pUrl.username.empty());
+        EXPECT_TRUE(pUrl.password.empty());
+        EXPECT_EQ(pUrl.domain, "domain");
+        EXPECT_EQ(*pUrl.port, 234);  // NOLINT(bugprone-unchecked-optional-access)
+        EXPECT_EQ(pUrl.path, "/");
+    }
+
+    {
+        ParsedUrl pUrl;
+        EXPECT_TRUE(parseUrl(pUrl, "Mixed://domain/path"));
+        EXPECT_EQ(pUrl.scheme, "mixed");
+        EXPECT_TRUE(pUrl.username.empty());
+        EXPECT_TRUE(pUrl.password.empty());
+        EXPECT_EQ(pUrl.domain, "domain");
+        EXPECT_FALSE(pUrl.port);
+        EXPECT_EQ(pUrl.path, "/path");
+    }
+
+    {
+        ParsedUrl pUrl;
+        EXPECT_TRUE(parseUrl(pUrl, "scheme://[::1]:123/path"));
+        EXPECT_EQ(pUrl.scheme, "scheme");
+        EXPECT_TRUE(pUrl.username.empty());
+        EXPECT_TRUE(pUrl.password.empty());
+        EXPECT_EQ(pUrl.domain, "::1");
+        EXPECT_EQ(*pUrl.port, 123);  // NOLINT(bugprone-unchecked-optional-access)
+        EXPECT_EQ(pUrl.path, "/path");
+    }
+
+    {
+        ParsedUrl pUrl;
+        EXPECT_TRUE(parseUrl(pUrl, "scheme://user:pass@domain:123/abc:321"));
+        EXPECT_EQ(pUrl.scheme, "scheme");
+        EXPECT_EQ(pUrl.username, "user");
+        EXPECT_EQ(pUrl.password, "pass");
+        EXPECT_EQ(pUrl.domain, "domain");
+        EXPECT_EQ(*pUrl.port, 123);  // NOLINT(bugprone-unchecked-optional-access)
+        EXPECT_EQ(pUrl.path, "/abc:321");
+    }
+
+    {
+        ParsedUrl pUrl;
+        EXPECT_TRUE(parseUrl(pUrl, "scheme://user@domain:123/abc:321"));
+        EXPECT_EQ(pUrl.scheme, "scheme");
+        EXPECT_EQ(pUrl.username, "user");
+        EXPECT_TRUE(pUrl.password.empty());
+        EXPECT_EQ(pUrl.domain, "domain");
+        EXPECT_EQ(*pUrl.port, 123);  // NOLINT(bugprone-unchecked-optional-access)
+        EXPECT_EQ(pUrl.path, "/abc:321");
+    }
+
+    {
+        ParsedUrl pUrl;
+        EXPECT_TRUE(parseUrl(pUrl, "scheme://:pass@domain:123/abc:321"));
+        EXPECT_EQ(pUrl.scheme, "scheme");
+        EXPECT_TRUE(pUrl.username.empty());
+        EXPECT_EQ(pUrl.password, "pass");
+        EXPECT_EQ(pUrl.domain, "domain");
+        EXPECT_EQ(*pUrl.port, 123);  // NOLINT(bugprone-unchecked-optional-access)
+        EXPECT_EQ(pUrl.path, "/abc:321");
+    }
+
+    {
+        ParsedUrl pUrl;
+        EXPECT_TRUE(parseUrl(pUrl, "scheme://domain:123/abc:321"));
+        EXPECT_EQ(pUrl.scheme, "scheme");
+        EXPECT_TRUE(pUrl.username.empty());
+        EXPECT_TRUE(pUrl.password.empty());
+        EXPECT_EQ(pUrl.domain, "domain");
+        EXPECT_EQ(*pUrl.port, 123);  // NOLINT(bugprone-unchecked-optional-access)
+        EXPECT_EQ(pUrl.path, "/abc:321");
+    }
+
+    {
+        ParsedUrl pUrl;
+        EXPECT_TRUE(parseUrl(pUrl, "scheme://user:pass@domain/abc:321"));
+        EXPECT_EQ(pUrl.scheme, "scheme");
+        EXPECT_EQ(pUrl.username, "user");
+        EXPECT_EQ(pUrl.password, "pass");
+        EXPECT_EQ(pUrl.domain, "domain");
+        EXPECT_FALSE(pUrl.port);
+        EXPECT_EQ(pUrl.path, "/abc:321");
+    }
+
+    {
+        ParsedUrl pUrl;
+        EXPECT_TRUE(parseUrl(pUrl, "scheme://user@domain/abc:321"));
+        EXPECT_EQ(pUrl.scheme, "scheme");
+        EXPECT_EQ(pUrl.username, "user");
+        EXPECT_TRUE(pUrl.password.empty());
+        EXPECT_EQ(pUrl.domain, "domain");
+        EXPECT_FALSE(pUrl.port);
+        EXPECT_EQ(pUrl.path, "/abc:321");
+    }
+
+    {
+        ParsedUrl pUrl;
+        EXPECT_TRUE(parseUrl(pUrl, "scheme://:pass@domain/abc:321"));
+        EXPECT_EQ(pUrl.scheme, "scheme");
+        EXPECT_TRUE(pUrl.username.empty());
+        EXPECT_EQ(pUrl.password, "pass");
+        EXPECT_EQ(pUrl.domain, "domain");
+        EXPECT_FALSE(pUrl.port);
+        EXPECT_EQ(pUrl.path, "/abc:321");
+    }
+
+    {
+        ParsedUrl pUrl;
+        EXPECT_TRUE(parseUrl(pUrl, "scheme://domain/abc:321"));
+        EXPECT_EQ(pUrl.scheme, "scheme");
+        EXPECT_TRUE(pUrl.username.empty());
+        EXPECT_TRUE(pUrl.password.empty());
+        EXPECT_EQ(pUrl.domain, "domain");
+        EXPECT_FALSE(pUrl.port);
+        EXPECT_EQ(pUrl.path, "/abc:321");
+    }
+
+    {
+        ParsedUrl pUrl;
+        EXPECT_TRUE(parseUrl(pUrl, "scheme:///path/to/file"));
+        EXPECT_EQ(pUrl.scheme, "scheme");
+        EXPECT_TRUE(pUrl.username.empty());
+        EXPECT_TRUE(pUrl.password.empty());
+        EXPECT_TRUE(pUrl.domain.empty());
+        EXPECT_FALSE(pUrl.port);
+        EXPECT_EQ(pUrl.path, "/path/to/file");
+    }
+
+    {
+        ParsedUrl pUrl;
+        EXPECT_TRUE(parseUrl(pUrl, "scheme://user:pass@domain/path/with/an@sign"));
+        EXPECT_EQ(pUrl.scheme, "scheme");
+        EXPECT_EQ(pUrl.username, "user");
+        EXPECT_EQ(pUrl.password, "pass");
+        EXPECT_EQ(pUrl.domain, "domain");
+        EXPECT_FALSE(pUrl.port);
+        EXPECT_EQ(pUrl.path, "/path/with/an@sign");
+    }
+
+    {
+        ParsedUrl pUrl;
+        EXPECT_TRUE(parseUrl(pUrl, "scheme://domain/path/with/an@sign"));
+        EXPECT_EQ(pUrl.scheme, "scheme");
+        EXPECT_TRUE(pUrl.username.empty());
+        EXPECT_TRUE(pUrl.password.empty());
+        EXPECT_EQ(pUrl.domain, "domain");
+        EXPECT_FALSE(pUrl.port);
+        EXPECT_EQ(pUrl.path, "/path/with/an@sign");
+    }
+
+    {
+        ParsedUrl pUrl;
+        EXPECT_TRUE(parseUrl(pUrl, "scheme://:999/"));
+        EXPECT_EQ(pUrl.scheme, "scheme");
+        EXPECT_TRUE(pUrl.username.empty());
+        EXPECT_TRUE(pUrl.password.empty());
+        EXPECT_EQ(pUrl.domain, ":999");
+        EXPECT_FALSE(pUrl.port);
+        EXPECT_EQ(pUrl.path, "/");
+    }
+
+    {
+        ParsedUrl pUrl;
+        EXPECT_TRUE(parseUrl(pUrl, "http://::1:1234/validators"));
+        EXPECT_EQ(pUrl.scheme, "http");
+        EXPECT_TRUE(pUrl.username.empty());
+        EXPECT_TRUE(pUrl.password.empty());
+        EXPECT_EQ(pUrl.domain, "::0.1.18.52");
+        EXPECT_FALSE(pUrl.port);
+        EXPECT_EQ(pUrl.path, "/validators");
+    }
+
+    // Expected fails.
+    {
+        ParsedUrl pUrl;
+        EXPECT_FALSE(parseUrl(pUrl, ""));
+        EXPECT_FALSE(parseUrl(pUrl, "nonsense"));
+        EXPECT_FALSE(parseUrl(pUrl, "://"));
+        EXPECT_FALSE(parseUrl(pUrl, ":///"));
+        EXPECT_FALSE(parseUrl(pUrl, "scheme://user:pass@domain:65536/abc:321"));
+        EXPECT_FALSE(parseUrl(pUrl, "UPPER://domain:23498765/"));
+        EXPECT_FALSE(parseUrl(pUrl, "UPPER://domain:0/"));
+        EXPECT_FALSE(parseUrl(pUrl, "UPPER://domain:+7/"));
+        EXPECT_FALSE(parseUrl(pUrl, "UPPER://domain:-7234/"));
+        EXPECT_FALSE(parseUrl(pUrl, "UPPER://domain:@#$56!/"));
+    }
+
+    {
+        std::string const strUrl("s://" + std::string(8192, ':'));
+        ParsedUrl pUrl;
+        EXPECT_FALSE(parseUrl(pUrl, strUrl));
+    }
+}
+
+TEST_F(StringUtilitiesTest, to_string)
+{
+    auto result = to_string("hello");
+    EXPECT_EQ(result, "hello");
+}
+
+}  // namespace xrpl

src/tests/libxrpl/basics/TaggedCache.cpp

@@ -0,0 +1,246 @@
+#include <xrpl/basics/TaggedCache.h>
+
+#include <xrpl/basics/IntrusivePointer.h>
+#include <xrpl/basics/IntrusiveRefCounts.h>
+#include <xrpl/basics/TaggedCache.ipp>  // IWYU pragma: keep
+#include <xrpl/basics/chrono.h>
+#include <xrpl/beast/utility/Journal.h>
+#include <xrpl/protocol/Protocol.h>
+
+#include <gtest/gtest.h>
+#include <helpers/TestSink.h>
+
+#include <memory>
+#include <string>
+#include <utility>
+
+namespace xrpl {
+
+/*
+I guess you can put some items in, make sure they're still there. Let some
+time pass, make sure they're gone. Keep a strong pointer to one of them, make
+sure you can still find it even after time passes. Create two objects with
+the same key, canonicalize them both and make sure you get the same object.
+Put an object in but keep a strong pointer to it, advance the clock a lot,
+then canonicalize a new object with the same key, make sure you get the
+original object.
+*/
+
+TEST(TaggedCacheTest, tagged_cache)
+{
+    using namespace std::chrono_literals;
+    beast::Journal const journal{TestSink::instance()};
+
+    TestStopwatch clock;
+    clock.set(0);
+
+    using Key = LedgerIndex;
+    using Value = std::string;
+    using Cache = TaggedCache<Key, Value>;
+
+    Cache c("test", 1, 1s, clock, journal);
+
+    // Insert an item, retrieve it, and age it so it gets purged.
+    {
+        EXPECT_EQ(c.getCacheSize(), 0);
+        EXPECT_EQ(c.getTrackSize(), 0);
+        EXPECT_FALSE(c.insert(1, "one"));
+        EXPECT_EQ(c.getCacheSize(), 1);
+        EXPECT_EQ(c.getTrackSize(), 1);
+
+        {
+            std::string s;
+            EXPECT_TRUE(c.retrieve(1, s));
+            EXPECT_EQ(s, "one");
+        }
+
+        ++clock;
+        c.sweep();
+        EXPECT_EQ(c.getCacheSize(), 0);
+        EXPECT_EQ(c.getTrackSize(), 0);
+    }
+
+    // Insert an item, maintain a strong pointer, age it, and
+    // verify that the entry still exists.
+    {
+        EXPECT_FALSE(c.insert(2, "two"));
+        EXPECT_EQ(c.getCacheSize(), 1);
+        EXPECT_EQ(c.getTrackSize(), 1);
+
+        {
+            auto p = c.fetch(2);
+            EXPECT_NE(p, nullptr);
+            ++clock;
+            c.sweep();
+            EXPECT_EQ(c.getCacheSize(), 0);
+            EXPECT_EQ(c.getTrackSize(), 1);
+        }
+
+        // Make sure its gone now that our reference is gone
+        ++clock;
+        c.sweep();
+        EXPECT_EQ(c.getCacheSize(), 0);
+        EXPECT_EQ(c.getTrackSize(), 0);
+    }
+
+    // Insert the same key/value pair and make sure we get the same result
+    {
+        EXPECT_FALSE(c.insert(3, "three"));
+
+        {
+            auto const p1 = c.fetch(3);
+            auto p2 = std::make_shared<Value>("three");
+            c.canonicalizeReplaceClient(3, p2);
+            EXPECT_EQ(p1.get(), p2.get());
+        }
+        ++clock;
+        c.sweep();
+        EXPECT_EQ(c.getCacheSize(), 0);
+        EXPECT_EQ(c.getTrackSize(), 0);
+    }
+
+    // Put an object in but keep a strong pointer to it, advance the clock a
+    // lot, then canonicalize a new object with the same key, make sure you
+    // get the original object.
+    {
+        // Put an object in
+        EXPECT_FALSE(c.insert(4, "four"));
+        EXPECT_EQ(c.getCacheSize(), 1);
+        EXPECT_EQ(c.getTrackSize(), 1);
+
+        {
+            // Keep a strong pointer to it
+            auto const p1 = c.fetch(4);
+            EXPECT_NE(p1, nullptr);
+            EXPECT_EQ(c.getCacheSize(), 1);
+            EXPECT_EQ(c.getTrackSize(), 1);
+            // Advance the clock a lot
+            ++clock;
+            c.sweep();
+            EXPECT_EQ(c.getCacheSize(), 0);
+            EXPECT_EQ(c.getTrackSize(), 1);
+            // Canonicalize a new object with the same key
+            auto p2 = std::make_shared<std::string>("four");
+            EXPECT_TRUE(c.canonicalizeReplaceClient(4, p2));
+            EXPECT_EQ(c.getCacheSize(), 1);
+            EXPECT_EQ(c.getTrackSize(), 1);
+            // Make sure we get the original object
+            EXPECT_EQ(p1.get(), p2.get());
+        }
+
+        ++clock;
+        c.sweep();
+        EXPECT_EQ(c.getCacheSize(), 0);
+        EXPECT_EQ(c.getTrackSize(), 0);
+    }
+
+    {
+        EXPECT_FALSE(c.insert(5, "five"));
+        EXPECT_EQ(c.getCacheSize(), 1);
+        EXPECT_EQ(c.size(), 1);
+
+        {
+            auto const p1 = c.fetch(5);
+            EXPECT_NE(p1, nullptr);
+            EXPECT_EQ(c.getCacheSize(), 1);
+            EXPECT_EQ(c.size(), 1);
+
+            // Advance the clock a lot
+            ++clock;
+            c.sweep();
+            EXPECT_EQ(c.getCacheSize(), 0);
+            EXPECT_EQ(c.size(), 1);
+
+            auto p2 = std::make_shared<std::string>("five_2");
+            EXPECT_TRUE(c.canonicalizeReplaceCache(5, p2));
+            EXPECT_EQ(c.getCacheSize(), 1);
+            EXPECT_EQ(c.size(), 1);
+            // Make sure the caller's original pointer is unchanged
+            EXPECT_NE(p1.get(), p2.get());
+            EXPECT_EQ(*p2, "five_2");
+
+            auto const p3 = c.fetch(5);
+            EXPECT_NE(p3, nullptr);
+            EXPECT_EQ(p3.get(), p2.get());
+            EXPECT_NE(p3.get(), p1.get());
+        }
+
+        ++clock;
+        c.sweep();
+        EXPECT_EQ(c.getCacheSize(), 0);
+        EXPECT_EQ(c.size(), 0);
+    }
+
+    {
+        struct MyRefCountObject : IntrusiveRefCounts
+        {
+            std::string data;
+
+            // Needed to support weak intrusive pointers
+            virtual void
+            partialDestructor()
+            {
+            }
+
+            MyRefCountObject() = default;
+            explicit MyRefCountObject(std::string data) : data(std::move(data))
+            {
+            }
+
+            bool
+            operator==(std::string const& other) const
+            {
+                return data == other;
+            }
+        };
+
+        using IntrPtrCache = TaggedCache<
+            Key,
+            MyRefCountObject,
+            /*IsKeyCache*/ false,
+            intr_ptr::SharedWeakUnionPtr<MyRefCountObject>,
+            intr_ptr::SharedPtr<MyRefCountObject>>;
+
+        IntrPtrCache intrPtrCache("IntrPtrTest", 1, 1s, clock, journal);
+
+        intrPtrCache.canonicalizeReplaceCache(1, intr_ptr::makeShared<MyRefCountObject>("one"));
+        EXPECT_EQ(intrPtrCache.getCacheSize(), 1);
+        EXPECT_EQ(intrPtrCache.size(), 1);
+
+        {
+            {
+                intrPtrCache.canonicalizeReplaceCache(
+                    1, intr_ptr::makeShared<MyRefCountObject>("one_replaced"));
+
+                auto p = intrPtrCache.fetch(1);
+                EXPECT_EQ(*p, "one_replaced");
+
+                // Advance the clock a lot
+                ++clock;
+                intrPtrCache.sweep();
+                EXPECT_EQ(intrPtrCache.getCacheSize(), 0);
+                EXPECT_EQ(intrPtrCache.size(), 1);
+
+                intrPtrCache.canonicalizeReplaceCache(
+                    1, intr_ptr::makeShared<MyRefCountObject>("one_replaced_2"));
+
+                auto p2 = intrPtrCache.fetch(1);
+                EXPECT_EQ(*p2, "one_replaced_2");
+
+                intrPtrCache.del(1, true);
+            }
+
+            intrPtrCache.canonicalizeReplaceCache(
+                1, intr_ptr::makeShared<MyRefCountObject>("one_replaced_3"));
+            auto p3 = intrPtrCache.fetch(1);
+            EXPECT_EQ(*p3, "one_replaced_3");
+        }
+
+        ++clock;
+        intrPtrCache.sweep();
+        EXPECT_EQ(intrPtrCache.getCacheSize(), 0);
+        EXPECT_EQ(intrPtrCache.size(), 0);
+    }
+}
+
+}  // namespace xrpl

src/tests/libxrpl/basics/Units.cpp

@@ -0,0 +1,328 @@
+#include <xrpl/protocol/Units.h>
+
+#include <xrpl/beast/utility/Zero.h>
+#include <xrpl/json/json_value.h>
+#include <xrpl/protocol/SystemParameters.h>
+#include <xrpl/protocol/XRPAmount.h>
+
+#include <gtest/gtest.h>
+
+#include <cstdint>
+#include <limits>
+#include <type_traits>
+
+namespace xrpl::test {
+
+TEST(UnitsTest, types)
+{
+    using FeeLevel32 = FeeLevel<std::uint32_t>;
+
+    {
+        XRPAmount const x{100};
+        EXPECT_EQ(x.drops(), 100);
+        EXPECT_TRUE((std::is_same_v<decltype(x)::unit_type, unit::dropTag>));
+        auto y = 4u * x;
+        EXPECT_EQ(y.value(), 400);
+        EXPECT_TRUE((std::is_same_v<decltype(y)::unit_type, unit::dropTag>));
+
+        auto z = 4 * y;
+        EXPECT_EQ(z.value(), 1600);
+        EXPECT_TRUE((std::is_same_v<decltype(z)::unit_type, unit::dropTag>));
+
+        FeeLevel32 const f{10};
+        FeeLevel32 const baseFee{100};
+
+        auto drops = mulDiv(baseFee, x, f);
+
+        EXPECT_TRUE(drops);
+        EXPECT_EQ(drops.value(), 1000);  // NOLINT(bugprone-unchecked-optional-access)
+        EXPECT_TRUE(
+            (std::is_same_v<std::remove_reference_t<decltype(*drops)>::unit_type, unit::dropTag>));
+
+        EXPECT_TRUE((std::is_same_v<std::remove_reference_t<decltype(*drops)>, XRPAmount>));
+    }
+    {
+        XRPAmount const x{100};
+        EXPECT_EQ(x.value(), 100);
+        EXPECT_TRUE((std::is_same_v<decltype(x)::unit_type, unit::dropTag>));
+        auto y = 4u * x;
+        EXPECT_EQ(y.value(), 400);
+        EXPECT_TRUE((std::is_same_v<decltype(y)::unit_type, unit::dropTag>));
+
+        FeeLevel64 const f{10};
+        FeeLevel64 const baseFee{100};
+
+        auto drops = mulDiv(baseFee, x, f);
+
+        EXPECT_TRUE(drops);
+        EXPECT_EQ(drops.value(), 1000);  // NOLINT(bugprone-unchecked-optional-access)
+        EXPECT_TRUE(
+            (std::is_same_v<std::remove_reference_t<decltype(*drops)>::unit_type, unit::dropTag>));
+        EXPECT_TRUE((std::is_same_v<std::remove_reference_t<decltype(*drops)>, XRPAmount>));
+    }
+    {
+        FeeLevel64 const x{1024};
+        EXPECT_EQ(x.value(), 1024);
+        EXPECT_TRUE((std::is_same_v<decltype(x)::unit_type, unit::feelevelTag>));
+        std::uint64_t const m = 4;
+        auto y = m * x;
+        EXPECT_EQ(y.value(), 4096);
+        EXPECT_TRUE((std::is_same_v<decltype(y)::unit_type, unit::feelevelTag>));
+
+        XRPAmount const basefee{10};
+        FeeLevel64 const referencefee{256};
+
+        auto drops = mulDiv(x, basefee, referencefee);
+
+        EXPECT_TRUE(drops);
+        EXPECT_EQ(drops.value(), 40);  // NOLINT(bugprone-unchecked-optional-access)
+        EXPECT_TRUE(
+            (std::is_same_v<std::remove_reference_t<decltype(*drops)>::unit_type, unit::dropTag>));
+        EXPECT_TRUE((std::is_same_v<std::remove_reference_t<decltype(*drops)>, XRPAmount>));
+    }
+}
+
+TEST(UnitsTest, json)
+{
+    // Json value functionality
+    using FeeLevel32 = FeeLevel<std::uint32_t>;
+
+    {
+        FeeLevel32 const x{std::numeric_limits<std::uint32_t>::max()};
+        auto y = x.jsonClipped();
+        EXPECT_EQ(y.type(), json::ValueType::UInt);
+        EXPECT_EQ(y, json::Value{x.fee()});
+    }
+
+    {
+        FeeLevel32 const x{std::numeric_limits<std::uint32_t>::min()};
+        auto y = x.jsonClipped();
+        EXPECT_EQ(y.type(), json::ValueType::UInt);
+        EXPECT_EQ(y, json::Value{x.fee()});
+    }
+
+    {
+        FeeLevel64 const x{std::numeric_limits<std::uint64_t>::max()};
+        auto y = x.jsonClipped();
+        EXPECT_EQ(y.type(), json::ValueType::UInt);
+        EXPECT_EQ(y, json::Value{std::numeric_limits<std::uint32_t>::max()});
+    }
+
+    {
+        FeeLevel64 const x{std::numeric_limits<std::uint64_t>::min()};
+        auto y = x.jsonClipped();
+        EXPECT_EQ(y.type(), json::ValueType::UInt);
+        EXPECT_EQ(y, json::Value{0});
+    }
+
+    {
+        FeeLevelDouble const x{std::numeric_limits<double>::max()};
+        auto y = x.jsonClipped();
+        EXPECT_EQ(y.type(), json::ValueType::Real);
+        EXPECT_EQ(y, json::Value{std::numeric_limits<double>::max()});
+    }
+
+    {
+        FeeLevelDouble const x{std::numeric_limits<double>::min()};
+        auto y = x.jsonClipped();
+        EXPECT_EQ(y.type(), json::ValueType::Real);
+        EXPECT_EQ(y, json::Value{std::numeric_limits<double>::min()});
+    }
+
+    {
+        XRPAmount const x{std::numeric_limits<std::int64_t>::max()};
+        auto y = x.jsonClipped();
+        EXPECT_EQ(y.type(), json::ValueType::Int);
+        EXPECT_EQ(y, json::Value{std::numeric_limits<std::int32_t>::max()});
+    }
+
+    {
+        XRPAmount const x{std::numeric_limits<std::int64_t>::min()};
+        auto y = x.jsonClipped();
+        EXPECT_EQ(y.type(), json::ValueType::Int);
+        EXPECT_EQ(y, json::Value{std::numeric_limits<std::int32_t>::min()});
+    }
+}
+
+TEST(UnitsTest, functions)
+{
+    // Explicitly test every defined function for the ValueUnit class
+    // since some of them are templated, but not used anywhere else.
+    using FeeLevel32 = FeeLevel<std::uint32_t>;
+
+    {
+        auto make = [&](auto x) -> FeeLevel64 { return x; };
+        auto explicitmake = [&](auto x) -> FeeLevel64 { return FeeLevel64{x}; };
+
+        [[maybe_unused]]
+        FeeLevel64 const defaulted{};
+        FeeLevel64 test{0};
+        EXPECT_EQ(test.fee(), 0);
+
+        test = explicitmake(beast::kZero);
+        EXPECT_EQ(test.fee(), 0);
+
+        test = beast::kZero;
+        EXPECT_EQ(test.fee(), 0);
+
+        test = explicitmake(100u);
+        EXPECT_EQ(test.fee(), 100);
+
+        FeeLevel64 const targetSame{200u};
+        FeeLevel32 const targetOther{300u};
+        test = make(targetSame);
+        EXPECT_EQ(test.fee(), 200);
+        EXPECT_EQ(test, targetSame);
+        EXPECT_TRUE(test < FeeLevel64{1000});
+        EXPECT_TRUE(test > FeeLevel64{100});
+        test = make(targetOther);
+        EXPECT_EQ(test.fee(), 300);
+        EXPECT_EQ(test, targetOther);
+
+        test = std::uint64_t(200);
+        EXPECT_EQ(test.fee(), 200);
+        test = std::uint32_t(300);
+        EXPECT_EQ(test.fee(), 300);
+
+        test = targetSame;
+        EXPECT_EQ(test.fee(), 200);
+        test = targetOther.fee();
+        EXPECT_EQ(test.fee(), 300);
+        EXPECT_EQ(test, targetOther);
+
+        test = targetSame * 2;
+        EXPECT_EQ(test.fee(), 400);
+        test = 3 * targetSame;
+        EXPECT_EQ(test.fee(), 600);
+        test = targetSame / 10;
+        EXPECT_EQ(test.fee(), 20);
+
+        test += targetSame;
+        EXPECT_EQ(test.fee(), 220);
+
+        test -= targetSame;
+        EXPECT_EQ(test.fee(), 20);
+
+        test++;
+        EXPECT_EQ(test.fee(), 21);
+        ++test;
+        EXPECT_EQ(test.fee(), 22);
+        test--;
+        EXPECT_EQ(test.fee(), 21);
+        --test;
+        EXPECT_EQ(test.fee(), 20);
+
+        test *= 5;
+        EXPECT_EQ(test.fee(), 100);
+        test /= 2;
+        EXPECT_EQ(test.fee(), 50);
+        test %= 13;
+        EXPECT_EQ(test.fee(), 11);
+
+        /*
+        // illegal with unsigned
+        test = -test;
+        EXPECT_EQ(test.fee(), -11);
+        EXPECT_EQ(test.signum(), -1);
+        EXPECT_EQ(to_string(test), "-11");
+        */
+
+        EXPECT_TRUE(test);
+        test = 0;
+        EXPECT_FALSE(test);
+        EXPECT_EQ(test.signum(), 0);
+        test = targetSame;
+        EXPECT_EQ(test.signum(), 1);
+        EXPECT_EQ(to_string(test), "200");
+    }
+    {
+        auto make = [&](auto x) -> FeeLevelDouble { return x; };
+        auto explicitmake = [&](auto x) -> FeeLevelDouble { return FeeLevelDouble{x}; };
+
+        [[maybe_unused]]
+        FeeLevelDouble const defaulted{};
+        FeeLevelDouble test{0};
+        EXPECT_EQ(test.fee(), 0);
+
+        test = explicitmake(beast::kZero);
+        EXPECT_EQ(test.fee(), 0);
+
+        test = beast::kZero;
+        EXPECT_EQ(test.fee(), 0);
+
+        test = explicitmake(100.0);
+        EXPECT_EQ(test.fee(), 100);
+
+        FeeLevelDouble const targetSame{200.0};
+        FeeLevel64 const targetOther{300};
+        test = make(targetSame);
+        EXPECT_EQ(test.fee(), 200);
+        EXPECT_EQ(test, targetSame);
+        EXPECT_TRUE(test < FeeLevelDouble{1000.0});
+        EXPECT_TRUE(test > FeeLevelDouble{100.0});
+        test = targetOther.fee();
+        EXPECT_EQ(test.fee(), 300);
+        EXPECT_EQ(test, targetOther);
+
+        test = 200.0;
+        EXPECT_EQ(test.fee(), 200);
+        test = std::uint64_t(300);
+        EXPECT_EQ(test.fee(), 300);
+
+        test = targetSame;
+        EXPECT_EQ(test.fee(), 200);
+
+        test = targetSame * 2;
+        EXPECT_EQ(test.fee(), 400);
+        test = 3 * targetSame;
+        EXPECT_EQ(test.fee(), 600);
+        test = targetSame / 10;
+        EXPECT_EQ(test.fee(), 20);
+
+        test += targetSame;
+        EXPECT_EQ(test.fee(), 220);
+
+        test -= targetSame;
+        EXPECT_EQ(test.fee(), 20);
+
+        test++;
+        EXPECT_EQ(test.fee(), 21);
+        ++test;
+        EXPECT_EQ(test.fee(), 22);
+        test--;
+        EXPECT_EQ(test.fee(), 21);
+        --test;
+        EXPECT_EQ(test.fee(), 20);
+
+        test *= 5;
+        EXPECT_EQ(test.fee(), 100);
+        test /= 2;
+        EXPECT_EQ(test.fee(), 50);
+        /* illegal with floating
+        test %= 13;
+        EXPECT_EQ(test.fee(), 11);
+        */
+
+        // legal with signed
+        test = -test;
+        EXPECT_EQ(test.fee(), -50);
+        EXPECT_EQ(test.signum(), -1);
+        EXPECT_EQ(to_string(test), "-50.000000");
+
+        EXPECT_TRUE(test);
+        test = 0;
+        EXPECT_FALSE(test);
+        EXPECT_EQ(test.signum(), 0);
+        test = targetSame;
+        EXPECT_EQ(test.signum(), 1);
+        EXPECT_EQ(to_string(test), "200.000000");
+    }
+}
+
+TEST(UnitsTest, initial_xrp)
+{
+    EXPECT_EQ(kInitialXrp.drops(), 100'000'000'000'000'000);
+    EXPECT_EQ(kInitialXrp, XRPAmount{100'000'000'000'000'000});
+}
+
+}  // namespace xrpl::test

src/tests/libxrpl/basics/XRPAmount.cpp

@@ -0,0 +1,295 @@
+#include <xrpl/protocol/XRPAmount.h>
+
+#include <xrpl/beast/utility/Zero.h>
+
+#include <gtest/gtest.h>
+
+#include <cstdint>
+#include <limits>
+
+namespace xrpl {
+
+TEST(XRPAmountTest, sig_num)
+{
+    for (auto i : {-1, 0, 1})
+    {
+        XRPAmount const x(i);
+
+        if (i < 0)
+        {
+            EXPECT_TRUE(x.signum() < 0);
+        }
+        else if (i > 0)
+        {
+            EXPECT_TRUE(x.signum() > 0);
+        }
+        else
+        {
+            EXPECT_EQ(x.signum(), 0);
+        }
+    }
+}
+
+TEST(XRPAmountTest, beast_zero)
+{
+    using beast::kZero;
+
+    for (auto i : {-1, 0, 1})
+    {
+        XRPAmount const x(i);
+
+        EXPECT_TRUE((i == 0) == (x == kZero));
+        EXPECT_TRUE((i != 0) == (x != kZero));
+        EXPECT_TRUE((i < 0) == (x < kZero));
+        EXPECT_TRUE((i > 0) == (x > kZero));
+        EXPECT_TRUE((i <= 0) == (x <= kZero));
+        EXPECT_TRUE((i >= 0) == (x >= kZero));
+
+        EXPECT_TRUE((0 == i) == (kZero == x));
+        EXPECT_TRUE((0 != i) == (kZero != x));
+        EXPECT_TRUE((0 < i) == (kZero < x));
+        EXPECT_TRUE((0 > i) == (kZero > x));
+        EXPECT_TRUE((0 <= i) == (kZero <= x));
+        EXPECT_TRUE((0 >= i) == (kZero >= x));
+    }
+}
+
+TEST(XRPAmountTest, comparisons)
+{
+    for (auto i : {-1, 0, 1})
+    {
+        XRPAmount const x(i);
+
+        for (auto j : {-1, 0, 1})
+        {
+            XRPAmount const y(j);
+
+            EXPECT_EQ((i == j), (x == y));
+            EXPECT_EQ((i != j), (x != y));
+            EXPECT_EQ((i < j), (x < y));
+            EXPECT_EQ((i > j), (x > y));
+            EXPECT_EQ((i <= j), (x <= y));
+            EXPECT_EQ((i >= j), (x >= y));
+        }
+    }
+}
+
+TEST(XRPAmountTest, add_sub)
+{
+    for (auto i : {-1, 0, 1})
+    {
+        XRPAmount const x(i);
+
+        for (auto j : {-1, 0, 1})
+        {
+            XRPAmount const y(j);
+
+            EXPECT_EQ(XRPAmount(i + j), (x + y));
+            EXPECT_EQ(XRPAmount(i - j), (x - y));
+
+            EXPECT_EQ((x + y), (y + x));  // addition is commutative
+        }
+    }
+}
+
+TEST(XRPAmountTest, decimal)
+{
+    // Tautology
+    EXPECT_EQ(kDropsPerXrp.decimalXRP(), 1);
+
+    XRPAmount test{1};
+    EXPECT_EQ(test.decimalXRP(), 0.000001);
+
+    test = -test;
+    EXPECT_EQ(test.decimalXRP(), -0.000001);
+
+    test = 100'000'000;
+    EXPECT_EQ(test.decimalXRP(), 100);
+
+    test = -test;
+    EXPECT_EQ(test.decimalXRP(), -100);
+}
+
+TEST(XRPAmountTest, functions)
+{
+    // Explicitly test every defined function for the XRPAmount class
+    // since some of them are templated, but not used anywhere else.
+    auto make = [&](auto x) -> XRPAmount { return XRPAmount{x}; };
+
+    XRPAmount const defaulted{};
+    (void)defaulted;
+    XRPAmount test{0};
+    EXPECT_EQ(test.drops(), 0);
+
+    test = make(beast::kZero);
+    EXPECT_EQ(test.drops(), 0);
+
+    test = beast::kZero;
+    EXPECT_EQ(test.drops(), 0);
+
+    test = make(100);
+    EXPECT_EQ(test.drops(), 100);
+
+    test = make(100u);
+    EXPECT_EQ(test.drops(), 100);
+
+    XRPAmount const targetSame{200u};
+    test = make(targetSame);
+    EXPECT_EQ(test.drops(), 200);
+    EXPECT_EQ(test, targetSame);
+    EXPECT_TRUE(test < XRPAmount{1000});
+    EXPECT_TRUE(test > XRPAmount{100});
+
+    test = std::int64_t(200);
+    EXPECT_EQ(test.drops(), 200);
+    test = std::uint32_t(300);
+    EXPECT_EQ(test.drops(), 300);
+
+    test = targetSame;
+    EXPECT_EQ(test.drops(), 200);
+    auto testOther = test.dropsAs<std::uint32_t>();
+    EXPECT_TRUE(testOther);
+    EXPECT_EQ(*testOther, 200);  // NOLINT(bugprone-unchecked-optional-access)
+    test = std::numeric_limits<std::uint64_t>::max();
+    testOther = test.dropsAs<std::uint32_t>();
+    EXPECT_FALSE(testOther);
+    test = -1;
+    testOther = test.dropsAs<std::uint32_t>();
+    EXPECT_FALSE(testOther);
+
+    test = targetSame * 2;
+    EXPECT_EQ(test.drops(), 400);
+    test = 3 * targetSame;
+    EXPECT_EQ(test.drops(), 600);
+    test = 20;
+    EXPECT_EQ(test.drops(), 20);
+
+    test += targetSame;
+    EXPECT_EQ(test.drops(), 220);
+
+    test -= targetSame;
+    EXPECT_EQ(test.drops(), 20);
+
+    test *= 5;
+    EXPECT_EQ(test.drops(), 100);
+    test = 50;
+    EXPECT_EQ(test.drops(), 50);
+    test -= 39;
+    EXPECT_EQ(test.drops(), 11);
+
+    // legal with signed
+    test = -test;
+    EXPECT_EQ(test.drops(), -11);
+    EXPECT_EQ(test.signum(), -1);
+    EXPECT_EQ(to_string(test), "-11");
+
+    EXPECT_TRUE(test);
+    test = 0;
+    EXPECT_FALSE(test);
+    EXPECT_EQ(test.signum(), 0);
+    test = targetSame;
+    EXPECT_EQ(test.signum(), 1);
+    EXPECT_EQ(to_string(test), "200");
+}
+
+TEST(XRPAmountTest, mul_ratio)
+{
+    constexpr auto kMaxUInt32 = std::numeric_limits<std::uint32_t>::max();
+    constexpr auto kMaxXrp = std::numeric_limits<XRPAmount::value_type>::max();
+    constexpr auto kMinXrp = std::numeric_limits<XRPAmount::value_type>::min();
+
+    {
+        // multiply by a number that would overflow then divide by the same
+        // number, and check we didn't lose any value
+        XRPAmount big(kMaxXrp);
+        EXPECT_EQ(big, mulRatio(big, kMaxUInt32, kMaxUInt32, true));
+        // rounding mode shouldn't matter as the result is exact
+        EXPECT_EQ(big, mulRatio(big, kMaxUInt32, kMaxUInt32, false));
+
+        // multiply and divide by values that would overflow if done
+        // naively, and check that it gives the correct answer
+        big -= 0xf;  // Subtract a little so it's divisible by 4
+        EXPECT_EQ(mulRatio(big, 3, 4, false).value(), (big.value() / 4) * 3);
+        EXPECT_EQ(mulRatio(big, 3, 4, true).value(), (big.value() / 4) * 3);
+        EXPECT_EQ(big.value() % 4, 0);
+        EXPECT_GT(big.value(), kMaxXrp / 3);
+        EXPECT_LE(big.value() / 4, kMaxXrp / 3);
+    }
+
+    {
+        // Similar test as above, but for negative values
+        XRPAmount big(kMinXrp);  // NOLINT TODO
+        EXPECT_EQ(big, mulRatio(big, kMaxUInt32, kMaxUInt32, true));
+        // rounding mode shouldn't matter as the result is exact
+        EXPECT_EQ(big, mulRatio(big, kMaxUInt32, kMaxUInt32, false));
+
+        // multiply and divide by values that would overflow if done
+        // naively, and check that it gives the correct answer
+        EXPECT_EQ(mulRatio(big, 3, 4, false).value(), (big.value() / 4) * 3);
+        EXPECT_EQ(mulRatio(big, 3, 4, true).value(), (big.value() / 4) * 3);
+        EXPECT_EQ(big.value() % 4, 0);
+        EXPECT_LT(big.value(), kMinXrp / 3);
+        EXPECT_GE(big.value() / 4, kMinXrp / 3);
+    }
+
+    {
+        // small amounts
+        XRPAmount const tiny(1);
+        // Round up should give the smallest allowable number
+        EXPECT_EQ(tiny, mulRatio(tiny, 1, kMaxUInt32, true));
+        // rounding down should be zero
+        EXPECT_EQ(beast::kZero, mulRatio(tiny, 1, kMaxUInt32, false));
+        EXPECT_EQ(beast::kZero, mulRatio(tiny, kMaxUInt32 - 1, kMaxUInt32, false));
+
+        // tiny negative numbers
+        XRPAmount const tinyNeg(-1);
+        // Round up should give zero
+        EXPECT_EQ(beast::kZero, mulRatio(tinyNeg, 1, kMaxUInt32, true));
+        EXPECT_EQ(beast::kZero, mulRatio(tinyNeg, kMaxUInt32 - 1, kMaxUInt32, true));
+        // rounding down should be tiny
+        EXPECT_EQ(tinyNeg, mulRatio(tinyNeg, kMaxUInt32 - 1, kMaxUInt32, false));
+    }
+
+    {  // rounding
+        {
+            XRPAmount const one(1);
+            auto const rup = mulRatio(one, kMaxUInt32 - 1, kMaxUInt32, true);
+            auto const rdown = mulRatio(one, kMaxUInt32 - 1, kMaxUInt32, false);
+            EXPECT_EQ(rup.drops() - rdown.drops(), 1);
+        }
+
+        {
+            XRPAmount const big(kMaxXrp);
+            auto const rup = mulRatio(big, kMaxUInt32 - 1, kMaxUInt32, true);
+            auto const rdown = mulRatio(big, kMaxUInt32 - 1, kMaxUInt32, false);
+            EXPECT_EQ(rup.drops() - rdown.drops(), 1);
+        }
+
+        {
+            XRPAmount const negOne(-1);
+            auto const rup = mulRatio(negOne, kMaxUInt32 - 1, kMaxUInt32, true);
+            auto const rdown = mulRatio(negOne, kMaxUInt32 - 1, kMaxUInt32, false);
+            EXPECT_EQ(rup.drops() - rdown.drops(), 1);
+        }
+    }
+
+    {
+        // division by zero
+        XRPAmount const one(1);
+        EXPECT_ANY_THROW({ mulRatio(one, 1, 0, true); });
+    }
+
+    {
+        // overflow
+        XRPAmount const big(kMaxXrp);
+        EXPECT_ANY_THROW({ mulRatio(big, 2, 1, true); });
+    }
+
+    {
+        // underflow
+        XRPAmount const bigNegative(kMinXrp + 10);
+        EXPECT_EQ(mulRatio(bigNegative, 2, 1, true), kMinXrp);
+    }
+}
+
+}  // namespace xrpl

src/tests/libxrpl/basics/base58.cpp

@@ -0,0 +1,438 @@
+#include <xrpl/protocol/detail/token_errors.h>
+
+#include <boost/multiprecision/cpp_int.hpp>  // IWYU pragma: keep
+
+#include <gtest/gtest.h>
+
+#include <algorithm>
+#include <cassert>
+#include <cstdint>
+#include <cstring>
+#include <iomanip>
+#include <iostream>
+#include <limits>
+#include <ranges>
+#include <stdexcept>
+#include <string>
+#include <tuple>
+#include <vector>
+#ifndef _MSC_VER
+
+#include <xrpl/protocol/detail/b58_utils.h>
+#include <xrpl/protocol/tokens.h>
+
+#include <array>
+#include <cstddef>
+#include <random>
+#include <span>
+#include <sstream>
+
+namespace xrpl::test {
+namespace {
+
+[[nodiscard]] inline auto
+randEngine() -> std::mt19937&
+{
+    static std::mt19937 kR = [] {
+        std::random_device rd;
+        return std::mt19937{rd()};
+    }();
+    return kR;
+}
+
+constexpr int kNumTokenTypeIndexes = 9;
+
+[[nodiscard]] inline auto
+tokenTypeAndSize(int i) -> std::tuple<xrpl::TokenType, std::size_t>
+{
+    assert(i < kNumTokenTypeIndexes);
+
+    switch (i)
+    {
+        using enum xrpl::TokenType;
+        case 0:
+            return {None, 20};
+        case 1:
+            return {NodePublic, 32};
+        case 2:
+            return {NodePublic, 33};
+        case 3:
+            return {NodePrivate, 32};
+        case 4:
+            return {AccountID, 20};
+        case 5:
+            return {AccountPublic, 32};
+        case 6:
+            return {AccountPublic, 33};
+        case 7:
+            return {AccountSecret, 32};
+        case 8:
+            return {FamilySeed, 16};
+        default:
+            throw std::invalid_argument(
+                "Invalid token selection passed to tokenTypeAndSize() "
+                "in " __FILE__);
+    }
+}
+
+[[nodiscard]] inline auto
+randomTokenTypeAndSize() -> std::tuple<xrpl::TokenType, std::size_t>
+{
+    using namespace xrpl;
+    auto& rng = randEngine();
+    std::uniform_int_distribution<> d(0, 8);
+    return tokenTypeAndSize(d(rng));
+}
+
+// Return the token type and subspan of `d` to use as test data.
+[[nodiscard]] inline auto
+randomB256TestData(std::span<std::uint8_t> d)
+    -> std::tuple<xrpl::TokenType, std::span<std::uint8_t>>
+{
+    auto& rng = randEngine();
+    std::uniform_int_distribution<std::uint8_t> dist(0, 255);
+    auto [tokType, tokSize] = randomTokenTypeAndSize();
+    std::generate(d.begin(), d.begin() + tokSize, [&] { return dist(rng); });
+    return {tokType, d.subspan(0, tokSize)};
+}
+
+inline void
+printAsChar(std::span<std::uint8_t> a, std::span<std::uint8_t> b)
+{
+    auto asString = [](std::span<std::uint8_t> s) {
+        std::string r;
+        r.resize(s.size());
+        std::ranges::copy(s, r.begin());
+        return r;
+    };
+    auto sa = asString(a);
+    auto sb = asString(b);
+    std::cerr << "\n\n" << sa << "\n" << sb << "\n";
+}
+
+inline void
+printAsInt(std::span<std::uint8_t> a, std::span<std::uint8_t> b)
+{
+    auto asString = [](std::span<std::uint8_t> s) -> std::string {
+        std::stringstream sstr;
+        for (auto i : s)
+        {
+            sstr << std::setw(3) << int(i) << ',';
+        }
+        return sstr.str();
+    };
+    auto sa = asString(a);
+    auto sb = asString(b);
+    std::cerr << "\n\n" << sa << "\n" << sb << "\n";
+}
+
+}  // namespace
+
+namespace multiprecision_utils {
+
+boost::multiprecision::checked_uint512_t
+toBoostMP(std::span<std::uint64_t> in)
+{
+    boost::multiprecision::checked_uint512_t mbp = 0;
+    for (auto const& i : std::views::reverse(in))
+    {
+        mbp <<= 64;
+        mbp += i;
+    }
+    return mbp;
+}
+
+std::vector<std::uint64_t>
+randomBigInt(std::uint8_t minSize = 1, std::uint8_t maxSize = 5)
+{
+    auto eng = randEngine();
+    std::uniform_int_distribution<std::uint8_t> numCoeffDist(minSize, maxSize);
+    std::uniform_int_distribution<std::uint64_t> dist;
+    auto const numCoeff = numCoeffDist(eng);
+    std::vector<std::uint64_t> coeffs;
+    coeffs.reserve(numCoeff);
+    for (int i = 0; i < numCoeff; ++i)
+    {
+        coeffs.push_back(dist(eng));
+    }
+    return coeffs;
+}
+}  // namespace multiprecision_utils
+
+TEST(Base58Test, multiprecision)
+{
+    using namespace boost::multiprecision;
+
+    constexpr std::size_t kIters = 100000;
+    auto eng = randEngine();
+    std::uniform_int_distribution<std::uint64_t> dist;
+    std::uniform_int_distribution<std::uint64_t> dist1(1);
+    for (int i = 0; i < kIters; ++i)
+    {
+        std::uint64_t const d = dist(eng);
+        if (d == 0u)
+            continue;
+        auto bigInt = multiprecision_utils::randomBigInt();
+        auto const boostBigInt =
+            multiprecision_utils::toBoostMP(std::span<std::uint64_t>(bigInt.data(), bigInt.size()));
+
+        auto const refDiv = boostBigInt / d;
+        auto const refMod = boostBigInt % d;
+
+        auto const mod = b58_fast::detail::inplaceBigintDivRem(
+            std::span<uint64_t>(bigInt.data(), bigInt.size()), d);
+        auto const foundDiv = multiprecision_utils::toBoostMP(bigInt);
+        EXPECT_EQ(refMod.convert_to<std::uint64_t>(), mod);
+        EXPECT_EQ(foundDiv, refDiv);
+    }
+    for (int i = 0; i < kIters; ++i)
+    {
+        std::uint64_t const d = dist(eng);
+        auto bigInt = multiprecision_utils::randomBigInt(/*minSize*/ 2);
+        if (bigInt[bigInt.size() - 1] == std::numeric_limits<std::uint64_t>::max())
+        {
+            bigInt[bigInt.size() - 1] -= 1;  // Prevent overflow
+        }
+        auto const boostBigInt =
+            multiprecision_utils::toBoostMP(std::span<std::uint64_t>(bigInt.data(), bigInt.size()));
+
+        auto const refAdd = boostBigInt + d;
+
+        auto const result = b58_fast::detail::inplaceBigintAdd(
+            std::span<uint64_t>(bigInt.data(), bigInt.size()), d);
+        EXPECT_EQ(result, TokenCodecErrc::Success);
+        auto const foundAdd = multiprecision_utils::toBoostMP(bigInt);
+        EXPECT_EQ(refAdd, foundAdd);
+    }
+    for (int i = 0; i < kIters; ++i)
+    {
+        std::uint64_t const d = dist1(eng);
+        // Force overflow
+        std::vector<std::uint64_t> bigInt(5, std::numeric_limits<std::uint64_t>::max());
+
+        auto const boostBigInt =
+            multiprecision_utils::toBoostMP(std::span<std::uint64_t>(bigInt.data(), bigInt.size()));
+
+        auto const refAdd = boostBigInt + d;
+
+        auto const result = b58_fast::detail::inplaceBigintAdd(
+            std::span<uint64_t>(bigInt.data(), bigInt.size()), d);
+        EXPECT_EQ(result, TokenCodecErrc::OverflowAdd);
+        auto const foundAdd = multiprecision_utils::toBoostMP(bigInt);
+        EXPECT_NE(refAdd, foundAdd);
+    }
+    for (int i = 0; i < kIters; ++i)
+    {
+        std::uint64_t const d = dist(eng);
+        auto bigInt = multiprecision_utils::randomBigInt(/* minSize */ 2);
+        // inplace mul requires the most significant coeff to be zero to
+        // hold the result.
+        bigInt[bigInt.size() - 1] = 0;
+        auto const boostBigInt =
+            multiprecision_utils::toBoostMP(std::span<std::uint64_t>(bigInt.data(), bigInt.size()));
+
+        auto const refMul = boostBigInt * d;
+
+        auto const result = b58_fast::detail::inplaceBigintMul(
+            std::span<uint64_t>(bigInt.data(), bigInt.size()), d);
+        EXPECT_EQ(result, TokenCodecErrc::Success);
+        auto const foundMul = multiprecision_utils::toBoostMP(bigInt);
+        EXPECT_EQ(refMul, foundMul);
+    }
+    for (int i = 0; i < kIters; ++i)
+    {
+        std::uint64_t const d = dist1(eng);
+        // Force overflow
+        std::vector<std::uint64_t> bigInt(5, std::numeric_limits<std::uint64_t>::max());
+        auto const boostBigInt =
+            multiprecision_utils::toBoostMP(std::span<std::uint64_t>(bigInt.data(), bigInt.size()));
+
+        auto const refMul = boostBigInt * d;
+
+        auto const result = b58_fast::detail::inplaceBigintMul(
+            std::span<uint64_t>(bigInt.data(), bigInt.size()), d);
+        EXPECT_EQ(result, TokenCodecErrc::InputTooLarge);
+        auto const foundMul = multiprecision_utils::toBoostMP(bigInt);
+        EXPECT_NE(refMul, foundMul);
+    }
+}
+
+TEST(Base58Test, fast_matches_ref)
+{
+    auto testRawEncode = [&](std::span<std::uint8_t> const& b256Data) {
+        std::array<std::uint8_t, 64> b58ResultBuf[2];
+        std::array<std::span<std::uint8_t>, 2> b58Result;
+
+        std::array<std::uint8_t, 64> b256ResultBuf[2];
+        std::array<std::span<std::uint8_t>, 2> b256Result;
+        for (int i = 0; i < 2; ++i)
+        {
+            std::span const outBuf{b58ResultBuf[i]};
+            if (i == 0)
+            {
+                auto const r = xrpl::b58_fast::detail::b256ToB58Be(b256Data, outBuf);
+                EXPECT_TRUE(r);
+                b58Result[i] = r.value();
+            }
+            else
+            {
+                std::array<std::uint8_t, 128> tmpBuf{};
+                std::string const s = xrpl::b58_ref::detail::encodeBase58(
+                    b256Data.data(), b256Data.size(), tmpBuf.data(), tmpBuf.size());
+                EXPECT_TRUE(s.size());
+                b58Result[i] = outBuf.subspan(0, s.size());
+                std::ranges::copy(s, b58Result[i].begin());
+            }
+        }
+        auto const rawB58SameSize = b58Result[0].size() == b58Result[1].size();
+        EXPECT_TRUE(rawB58SameSize);
+        if (rawB58SameSize)
+        {
+            auto const rawB58SameData =
+                memcmp(b58Result[0].data(), b58Result[1].data(), b58Result[0].size()) == 0;
+            EXPECT_TRUE(rawB58SameData);
+            if (!rawB58SameData)
+            {
+                printAsChar(b58Result[0], b58Result[1]);
+            }
+        }
+
+        for (int i = 0; i < 2; ++i)
+        {
+            std::span const outBuf{b256ResultBuf[i].data(), b256ResultBuf[i].size()};
+            if (i == 0)
+            {
+                std::string const in(
+                    b58Result[i].data(), b58Result[i].data() + b58Result[i].size());
+                auto const r = xrpl::b58_fast::detail::b58ToB256Be(in, outBuf);
+                EXPECT_TRUE(r);
+                b256Result[i] = r.value();
+            }
+            else
+            {
+                std::string const st(b58Result[i].begin(), b58Result[i].end());
+                std::string const s = xrpl::b58_ref::detail::decodeBase58(st);
+                EXPECT_TRUE(s.size());
+                b256Result[i] = outBuf.subspan(0, s.size());
+                std::ranges::copy(s, b256Result[i].begin());
+            }
+        }
+
+        auto const rawB256SameSize = b256Result[0].size() == b256Result[1].size();
+        EXPECT_TRUE(rawB256SameSize);
+        if (rawB256SameSize)
+        {
+            auto const rawB256SameData =
+                memcmp(b256Result[0].data(), b256Result[1].data(), b256Result[0].size()) == 0;
+            EXPECT_TRUE(rawB256SameData);
+            if (!rawB256SameData)
+            {
+                printAsInt(b256Result[0], b256Result[1]);
+            }
+        }
+    };
+
+    auto testTokenEncode = [&](xrpl::TokenType const tokType,
+                               std::span<std::uint8_t> const& b256Data) {
+        std::array<std::uint8_t, 64> b58ResultBuf[2];
+        std::array<std::span<std::uint8_t>, 2> b58Result;
+
+        std::array<std::uint8_t, 64> b256ResultBuf[2];
+        std::array<std::span<std::uint8_t>, 2> b256Result;
+        for (int i = 0; i < 2; ++i)
+        {
+            std::span const outBuf{b58ResultBuf[i].data(), b58ResultBuf[i].size()};
+            if (i == 0)
+            {
+                auto const r = xrpl::b58_fast::encodeBase58Token(tokType, b256Data, outBuf);
+                EXPECT_TRUE(r);
+                b58Result[i] = r.value();
+            }
+            else
+            {
+                std::string const s =
+                    xrpl::b58_ref::encodeBase58Token(tokType, b256Data.data(), b256Data.size());
+                EXPECT_TRUE(s.size());
+                b58Result[i] = outBuf.subspan(0, s.size());
+                std::ranges::copy(s, b58Result[i].begin());
+            }
+        }
+        auto const tokenB58SameSize = b58Result[0].size() == b58Result[1].size();
+        EXPECT_TRUE(tokenB58SameSize);
+        if (tokenB58SameSize)
+        {
+            auto const tokenB58SameData =
+                memcmp(b58Result[0].data(), b58Result[1].data(), b58Result[0].size()) == 0;
+            EXPECT_TRUE(tokenB58SameData);
+            if (!tokenB58SameData)
+            {
+                printAsChar(b58Result[0], b58Result[1]);
+            }
+        }
+
+        for (int i = 0; i < 2; ++i)
+        {
+            std::span const outBuf{b256ResultBuf[i].data(), b256ResultBuf[i].size()};
+            if (i == 0)
+            {
+                std::string const in(
+                    b58Result[i].data(), b58Result[i].data() + b58Result[i].size());
+                auto const r = xrpl::b58_fast::decodeBase58Token(tokType, in, outBuf);
+                EXPECT_TRUE(r);
+                b256Result[i] = r.value();
+            }
+            else
+            {
+                std::string const st(b58Result[i].begin(), b58Result[i].end());
+                std::string const s = xrpl::b58_ref::decodeBase58Token(st, tokType);
+                EXPECT_TRUE(s.size());
+                b256Result[i] = outBuf.subspan(0, s.size());
+                std::ranges::copy(s, b256Result[i].begin());
+            }
+        }
+
+        auto const tokenB256SameSize = b256Result[0].size() == b256Result[1].size();
+        EXPECT_TRUE(tokenB256SameSize);
+        if (tokenB256SameSize)
+        {
+            auto const tokenB256SameData =
+                memcmp(b256Result[0].data(), b256Result[1].data(), b256Result[0].size()) == 0;
+            EXPECT_TRUE(tokenB256SameData);
+            if (!tokenB256SameData)
+            {
+                printAsInt(b256Result[0], b256Result[1]);
+            }
+        }
+    };
+
+    auto testIt = [&](xrpl::TokenType const tokType, std::span<std::uint8_t> const& b256Data) {
+        testRawEncode(b256Data);
+        testTokenEncode(tokType, b256Data);
+    };
+
+    // test every token type with data where every byte is the same and the
+    // bytes range from 0-255
+    for (int i = 0; i < kNumTokenTypeIndexes; ++i)
+    {
+        std::array<std::uint8_t, 128> b256DataBuf{};
+        auto const [tokType, tokSize] = tokenTypeAndSize(i);
+        for (int d = 0; d <= 255; ++d)
+        {
+            memset(b256DataBuf.data(), d, tokSize);
+            testIt(tokType, std::span(b256DataBuf.data(), tokSize));
+        }
+    }
+
+    // test with random data
+    constexpr std::size_t kIters = 100000;
+    for (int i = 0; i < kIters; ++i)
+    {
+        std::array<std::uint8_t, 128> b256DataBuf{};
+        auto const [tokType, b256Data] = randomB256TestData(b256DataBuf);
+        testIt(tokType, b256Data);
+    }
+}
+
+}  // namespace xrpl::test
+
+#endif  // _MSC_VER

src/tests/libxrpl/basics/base_uint_test.cpp

@@ -0,0 +1,360 @@
+#include <xrpl/basics/Blob.h>
+#include <xrpl/basics/base_uint.h>
+#include <xrpl/basics/hardened_hash.h>
+#include <xrpl/beast/utility/Zero.h>
+
+#include <boost/endian/detail/order.hpp>
+
+#include <gtest/gtest.h>
+
+#include <array>
+#include <cassert>
+#include <complex>
+#include <cstddef>
+#include <cstdint>
+#include <iterator>
+#include <stdexcept>
+#include <string>
+#include <string_view>
+#include <type_traits>
+#include <unordered_set>
+#include <utility>
+#include <vector>
+
+namespace xrpl::test {
+
+// a non-hashing Hasher that just copies the bytes.
+// Used to test hash_append in base_uint
+template <std::size_t Bits>
+struct Nonhash
+{
+    static constexpr auto const kEndian = boost::endian::order::big;
+    static constexpr std::size_t kWidth = Bits / 8;
+
+    std::array<std::uint8_t, kWidth> data;
+
+    Nonhash() = default;
+
+    void
+    operator()(void const* key, std::size_t len) noexcept
+    {
+        assert(len == kWidth);
+        memcpy(data.data(), key, len);
+    }
+
+    explicit
+    operator std::size_t() noexcept
+    {
+        return kWidth;
+    }
+};
+
+struct BaseUintTest : public ::testing::Test
+{
+    using BaseUInt96 = BaseUInt<96>;
+    static_assert(std::is_copy_constructible_v<BaseUInt96>);
+    static_assert(std::is_copy_assignable_v<BaseUInt96>);
+
+    static void
+    testComparisons()
+    {
+        {
+            static constexpr std::array<std::pair<std::string_view, std::string_view>, 6> kTestArgs{
+                {{"0000000000000000", "0000000000000001"},
+                 {"0000000000000000", "ffffffffffffffff"},
+                 {"1234567812345678", "2345678923456789"},
+                 {"8000000000000000", "8000000000000001"},
+                 {"aaaaaaaaaaaaaaa9", "aaaaaaaaaaaaaaaa"},
+                 {"fffffffffffffffe", "ffffffffffffffff"}}};
+
+            for (auto const& arg : kTestArgs)
+            {
+                xrpl::BaseUInt<64> const u{arg.first}, v{arg.second};
+                // For code readability, we want to use general boolean
+                // expectations instead of specific EXPECT_LT etc.
+                EXPECT_TRUE(u < v);
+                EXPECT_TRUE(u <= v);
+                EXPECT_TRUE(u != v);
+                EXPECT_FALSE(u == v);
+                EXPECT_FALSE(u > v);
+                EXPECT_FALSE(u >= v);
+                EXPECT_FALSE(v < u);
+                EXPECT_FALSE(v <= u);
+                EXPECT_TRUE(v != u);
+                EXPECT_FALSE(v == u);
+                EXPECT_TRUE(v > u);
+                EXPECT_TRUE(v >= u);
+                EXPECT_TRUE(u == u);
+                EXPECT_TRUE(v == v);
+            }
+        }
+
+        {
+            static constexpr std::array<std::pair<std::string_view, std::string_view>, 6> kTestArgs{
+                {
+                    {"000000000000000000000000", "000000000000000000000001"},
+                    {"000000000000000000000000", "ffffffffffffffffffffffff"},
+                    {"0123456789ab0123456789ab", "123456789abc123456789abc"},
+                    {"555555555555555555555555", "55555555555a555555555555"},
+                    {"aaaaaaaaaaaaaaa9aaaaaaaa", "aaaaaaaaaaaaaaaaaaaaaaaa"},
+                    {"fffffffffffffffffffffffe", "ffffffffffffffffffffffff"},
+                }};
+
+            for (auto const& arg : kTestArgs)
+            {
+                xrpl::BaseUInt<96> const u{arg.first}, v{arg.second};
+                EXPECT_TRUE(u < v);
+                EXPECT_TRUE(u <= v);
+                EXPECT_TRUE(u != v);
+                EXPECT_FALSE(u == v);
+                EXPECT_FALSE(u > v);
+                EXPECT_FALSE(u >= v);
+                EXPECT_FALSE(v < u);
+                EXPECT_FALSE(v <= u);
+                EXPECT_TRUE(v != u);
+                EXPECT_FALSE(v == u);
+                EXPECT_TRUE(v > u);
+                EXPECT_TRUE(v >= u);
+                EXPECT_TRUE(u == u);
+                EXPECT_TRUE(v == v);
+            }
+        }
+    }
+};
+
+TEST_F(BaseUintTest, base_uint)
+{
+    static_assert(!std::is_constructible_v<BaseUInt96, std::complex<double>>);
+    static_assert(!std::is_assignable_v<BaseUInt96&, std::complex<double>>);
+
+    testComparisons();
+
+    // used to verify set insertion (hashing required)
+    std::unordered_set<BaseUInt96, HardenedHash<>> uset;
+
+    Blob const raw{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12};
+    EXPECT_EQ(BaseUInt96::kBytes, raw.size());
+
+    BaseUInt96 u = BaseUInt96::fromRaw(raw);
+    uset.insert(u);
+    EXPECT_EQ(raw.size(), u.size());
+    EXPECT_EQ(to_string(u), "0102030405060708090A0B0C");
+    EXPECT_EQ(toShortString(u), "01020304...");
+    EXPECT_EQ(*u.data(), 1);
+    EXPECT_EQ(u.signum(), 1);
+    EXPECT_FALSE(!u);
+    EXPECT_FALSE(u.isZero());
+    EXPECT_TRUE(u.isNonZero());
+    unsigned char t = 0;
+    for (auto& d : u)
+    {
+        EXPECT_EQ(d, ++t);
+    }
+
+    // Test hash_append by "hashing" with a no-op hasher (h)
+    // and then extracting the bytes that were written during hashing
+    // back into another base_uint (w) for comparison with the original
+    Nonhash<96> h{};
+    hash_append(h, u);
+    BaseUInt96 const w =
+        BaseUInt96::fromRaw(std::vector<std::uint8_t>(h.data.begin(), h.data.end()));
+    EXPECT_EQ(w, u);
+
+    BaseUInt96 v{~u};
+    uset.insert(v);
+    EXPECT_EQ(to_string(v), "FEFDFCFBFAF9F8F7F6F5F4F3");
+    EXPECT_EQ(toShortString(v), "FEFDFCFB...");
+    EXPECT_EQ(*v.data(), 0xfe);
+    EXPECT_EQ(v.signum(), 1);
+    EXPECT_FALSE(!v);
+    EXPECT_FALSE(v.isZero());
+    EXPECT_TRUE(v.isNonZero());
+
+    t = 0xff;
+    for (auto& d : v)
+    {
+        EXPECT_EQ(d, --t);
+    }
+
+    EXPECT_LT(u, v);
+    EXPECT_GT(v, u);
+
+    v = u;
+    EXPECT_EQ(v, u);
+
+    BaseUInt96 z{beast::kZero};
+    uset.insert(z);
+    EXPECT_EQ(to_string(z), "000000000000000000000000");
+    EXPECT_EQ(toShortString(z), "00000000...");
+    EXPECT_EQ(*z.data(), 0);
+    EXPECT_EQ(*z.begin(), 0);
+    EXPECT_EQ(*std::prev(z.end(), 1), 0);
+    EXPECT_EQ(z.signum(), 0);
+    EXPECT_TRUE(!z);
+    EXPECT_TRUE(z.isZero());
+    EXPECT_FALSE(z.isNonZero());
+    for (auto& d : z)
+    {
+        EXPECT_EQ(d, 0);
+    }
+
+    BaseUInt96 n{z};
+    n++;
+    EXPECT_EQ(n, BaseUInt96(1));
+    n--;
+    EXPECT_EQ(n, beast::kZero);
+    EXPECT_EQ(n, z);
+    n--;
+    EXPECT_EQ(to_string(n), "FFFFFFFFFFFFFFFFFFFFFFFF");
+    EXPECT_EQ(toShortString(n), "FFFFFFFF...");
+    n = beast::kZero;
+    EXPECT_EQ(n, z);
+
+    BaseUInt96 zp1{z};
+    zp1++;
+    BaseUInt96 zm1{z};
+    zm1--;
+    BaseUInt96 const x{zm1 ^ zp1};
+    uset.insert(x);
+    EXPECT_EQ(to_string(x), "FFFFFFFFFFFFFFFFFFFFFFFE") << to_string(x);
+    EXPECT_EQ(toShortString(x), "FFFFFFFF...") << toShortString(x);
+
+    EXPECT_EQ(uset.size(), 4);
+
+    BaseUInt96 tmp;
+    EXPECT_TRUE(tmp.parseHex(to_string(u)));
+    EXPECT_EQ(tmp, u);
+    tmp = z;
+
+    // fails with extra char
+    EXPECT_FALSE(tmp.parseHex("A" + to_string(u)));
+    tmp = z;
+
+    // fails with extra char at end
+    EXPECT_FALSE(tmp.parseHex(to_string(u) + "A"));
+
+    // fails with a non-hex character at some point in the string:
+    tmp = z;
+
+    for (std::size_t i = 0; i != 24; ++i)
+    {
+        std::string x = to_string(z);
+        x[i] = ('G' + (i % 10));
+        EXPECT_FALSE(tmp.parseHex(x));
+    }
+
+    // Walking 1s:
+    for (std::size_t i = 0; i != 24; ++i)
+    {
+        std::string s1 = "000000000000000000000000";
+        s1[i] = '1';
+
+        EXPECT_TRUE(tmp.parseHex(s1));
+        EXPECT_EQ(to_string(tmp), s1);
+    }
+
+    // Walking 0s:
+    for (std::size_t i = 0; i != 24; ++i)
+    {
+        std::string s1 = "111111111111111111111111";
+        s1[i] = '0';
+
+        EXPECT_TRUE(tmp.parseHex(s1));
+        EXPECT_EQ(to_string(tmp), s1);
+    }
+
+    // Constexpr constructors
+    {
+        static_assert(BaseUInt96{}.signum() == 0);
+        static_assert(BaseUInt96("0").signum() == 0);
+        static_assert(BaseUInt96("000000000000000000000000").signum() == 0);
+        static_assert(BaseUInt96("000000000000000000000001").signum() == 1);
+        static_assert(BaseUInt96("800000000000000000000000").signum() == 1);
+
+// Everything within the #if should fail during compilation.
+#if 0
+            // Too few characters
+            static_assert(BaseUInt96("00000000000000000000000").signum() == 0);
+
+            // Too many characters
+            static_assert(BaseUInt96("0000000000000000000000000").signum() == 0);
+
+            // Non-hex characters
+            static_assert(BaseUInt96("00000000000000000000000 ").signum() == 1);
+            static_assert(BaseUInt96("00000000000000000000000/").signum() == 1);
+            static_assert(BaseUInt96("00000000000000000000000:").signum() == 1);
+            static_assert(BaseUInt96("00000000000000000000000@").signum() == 1);
+            static_assert(BaseUInt96("00000000000000000000000G").signum() == 1);
+            static_assert(BaseUInt96("00000000000000000000000`").signum() == 1);
+            static_assert(BaseUInt96("00000000000000000000000g").signum() == 1);
+            static_assert(BaseUInt96("00000000000000000000000~").signum() == 1);
+#endif  // 0
+
+        // Using the constexpr constructor in a non-constexpr context
+        // with an error in the parsing throws an exception.
+        {
+            // Invalid length for string.
+            bool caught = false;
+            try
+            {
+                // Try to prevent constant evaluation.
+                std::vector<char> str(23, '7');
+                std::string_view const sView(str.data(), str.size());
+                [[maybe_unused]] BaseUInt96 const t96(sView);
+            }
+            catch (std::invalid_argument const& e)
+            {
+                EXPECT_EQ(e.what(), std::string("invalid length for hex string"));
+                caught = true;
+            }
+            EXPECT_TRUE(caught);
+        }
+        {
+            // Invalid character in string.
+            bool caught = false;
+            try
+            {
+                // Try to prevent constant evaluation.
+                std::vector<char> str(23, '7');
+                str.push_back('G');
+                std::string_view const sView(str.data(), str.size());
+                [[maybe_unused]] BaseUInt96 const t96(sView);
+            }
+            catch (std::range_error const& e)
+            {
+                EXPECT_EQ(e.what(), std::string("invalid hex character"));
+                caught = true;
+            }
+            EXPECT_TRUE(caught);
+        }
+
+        // Verify that constexpr base_uints interpret a string the same
+        // way parseHex() does.
+        struct StrBaseUInt
+        {
+            char const* const str;
+            BaseUInt96 tst;
+
+            constexpr StrBaseUInt(char const* s) : str(s), tst(s)
+            {
+            }
+        };
+        constexpr StrBaseUInt kTestCases[] = {
+            "000000000000000000000000",
+            "000000000000000000000001",
+            "fedcba9876543210ABCDEF91",
+            "19FEDCBA0123456789abcdef",
+            "800000000000000000000000",
+            "fFfFfFfFfFfFfFfFfFfFfFfF",
+        };
+
+        for (StrBaseUInt const& t : kTestCases)
+        {
+            BaseUInt96 t96;
+            EXPECT_TRUE(t96.parseHex(t.str));
+            EXPECT_EQ(t96, t.tst);
+        }
+    }
+}
+
+}  // namespace xrpl::test

src/tests/libxrpl/basics/hardened_hash.cpp

@@ -0,0 +1,227 @@
+#include <xrpl/basics/hardened_hash.h>
+
+#include <xrpl/beast/hash/hash_append.h>
+
+#include <gtest/gtest.h>
+
+#include <array>
+#include <cstddef>
+#include <cstdint>
+#include <iomanip>
+#include <ios>
+#include <ostream>
+#include <string>
+#include <type_traits>
+#include <unordered_map>
+#include <unordered_set>
+
+namespace xrpl::detail {
+
+template <class T>
+class TestUserTypeMember
+{
+private:
+    T t_;
+
+public:
+    explicit TestUserTypeMember(T const& t = T()) : t_(t)
+    {
+    }
+
+    template <class Hasher>
+    friend void
+    // NOLINTNEXTLINE(readability-identifier-naming)
+    hash_append(Hasher& h, TestUserTypeMember const& a) noexcept
+    {
+        using beast::hash_append;
+        hash_append(h, a.t_);
+    }
+};
+
+template <class T>
+class TestUserTypeFree
+{
+private:
+    T t_;
+
+public:
+    explicit TestUserTypeFree(T const& t = T()) : t_(t)
+    {
+    }
+
+    template <class Hasher>
+    friend void
+    // NOLINTNEXTLINE(readability-identifier-naming)
+    hash_append(Hasher& h, TestUserTypeFree const& a) noexcept
+    {
+        using beast::hash_append;
+        hash_append(h, a.t_);
+    }
+};
+
+}  // namespace xrpl::detail
+
+//------------------------------------------------------------------------------
+
+namespace xrpl {
+
+namespace detail {
+
+template <class T>
+using test_hardened_unordered_set = std::unordered_set<T, HardenedHash<>>;
+
+template <class T>
+using test_hardened_unordered_map = std::unordered_map<T, int, HardenedHash<>>;
+
+template <class T>
+using test_hardened_unordered_multiset = std::unordered_multiset<T, HardenedHash<>>;
+
+template <class T>
+using test_hardened_unordered_multimap = std::unordered_multimap<T, int, HardenedHash<>>;
+
+}  // namespace detail
+
+template <std::size_t Bits, class UInt = std::uint64_t>
+class UnsignedInteger
+{
+private:
+    static_assert(
+        std::is_integral_v<UInt> && std::is_unsigned_v<UInt>,
+        "UInt must be an unsigned integral type");
+
+    static_assert(Bits % (8 * sizeof(UInt)) == 0, "Bits must be a multiple of 8*sizeof(UInt)");
+
+    static_assert(Bits >= (8 * sizeof(UInt)), "Bits must be at least 8*sizeof(UInt)");
+
+    static std::size_t const kSize = Bits / (8 * sizeof(UInt));
+
+    std::array<UInt, kSize> vec_;
+
+public:
+    using value_type = UInt;
+
+    static std::size_t const kBits = Bits;
+    static std::size_t const kBytes = kBits / 8;
+
+    template <class Int>
+    static UnsignedInteger
+    fronumber(Int v)
+    {
+        UnsignedInteger result;
+        for (std::size_t i(1); i < kSize; ++i)
+            result.vec_[i] = 0;
+        result.vec_[0] = v;
+        return result;
+    }
+
+    void*
+    data() noexcept
+    {
+        return &vec_[0];
+    }
+
+    [[nodiscard]] void const*
+    data() const noexcept
+    {
+        return &vec_[0];
+    }
+
+    template <class Hasher>
+    friend void
+    hash_append(Hasher& h, UnsignedInteger const& a) noexcept
+    {
+        using beast::hash_append;
+        hash_append(h, a.vec_);
+    }
+
+    friend std::ostream&
+    operator<<(std::ostream& s, UnsignedInteger const& v)
+    {
+        for (std::size_t i(0); i < kSize; ++i)
+            s << std::hex << std::setfill('0') << std::setw(2 * sizeof(UInt)) << v.vec_[i];
+        return s;
+    }
+};
+
+using sha256_t = UnsignedInteger<256, std::size_t>;
+
+#ifndef __INTELLISENSE__
+static_assert(sha256_t::kBits == 256, "sha256_t must have 256 bits");
+#endif
+
+}  // namespace xrpl
+
+//------------------------------------------------------------------------------
+
+namespace xrpl {
+
+class HardenedHashTest : public ::testing::Test
+{
+public:
+    template <class T>
+    static void
+    check()
+    {
+        T t{};
+        HardenedHash<>()(t);
+        SUCCEED();
+    }
+
+    template <template <class T> class U>
+    static void
+    checkUserType()
+    {
+        check<U<bool>>();
+        check<U<char>>();
+        check<U<signed char>>();
+        check<U<unsigned char>>();
+        // These cause trouble for boost
+        // check <U <char16_t>> ();
+        // check <U <char32_t>> ();
+        check<U<wchar_t>>();
+        check<U<short>>();
+        check<U<unsigned short>>();
+        check<U<int>>();
+        check<U<unsigned int>>();
+        check<U<long>>();
+        check<U<long long>>();
+        check<U<unsigned long>>();
+        check<U<unsigned long long>>();
+        check<U<float>>();
+        check<U<double>>();
+        check<U<long double>>();
+    }
+
+    template <template <class T> class C>
+    static void
+    checkContainer()
+    {
+        {
+            C<detail::TestUserTypeMember<std::string>> const c;
+        }
+
+        SUCCEED();
+
+        {
+            C<detail::TestUserTypeFree<std::string>> const c;
+        }
+
+        SUCCEED();
+    }
+};
+
+TEST_F(HardenedHashTest, user_types)
+{
+    checkUserType<detail::TestUserTypeMember>();
+    checkUserType<detail::TestUserTypeFree>();
+}
+
+TEST_F(HardenedHashTest, containers)
+{
+    checkContainer<detail::test_hardened_unordered_set>();
+    checkContainer<detail::test_hardened_unordered_map>();
+    checkContainer<detail::test_hardened_unordered_multiset>();
+    checkContainer<detail::test_hardened_unordered_multimap>();
+}
+
+}  // namespace xrpl

src/tests/libxrpl/basics/join.cpp

@@ -0,0 +1,80 @@
+#include <xrpl/basics/join.h>
+
+#include <xrpl/basics/base_uint.h>
+
+#include <gtest/gtest.h>
+
+#include <array>
+#include <cstddef>
+#include <initializer_list>
+#include <sstream>
+#include <string>
+#include <vector>
+
+namespace xrpl::test {
+
+struct JoinTest : public ::testing::Test
+{
+};
+
+TEST_F(JoinTest, join)
+{
+    auto test = [](auto collectionanddelimiter, std::string expected) {
+        std::stringstream ss;
+        // Put something else in the buffer before and after to ensure that
+        // the << operator returns the stream correctly.
+        ss << "(" << collectionanddelimiter << ")";
+        auto const str = ss.str();
+        EXPECT_EQ(str.substr(1, str.length() - 2), expected);
+        EXPECT_EQ(str.front(), '(');
+        EXPECT_EQ(str.back(), ')');
+    };
+
+    // C++ array
+    test(CollectionAndDelimiter(std::array<int, 4>{2, -1, 5, 10}, "/"), "2/-1/5/10");
+    // One item C++ array edge case
+    test(CollectionAndDelimiter(std::array<std::string, 1>{"test"}, " & "), "test");
+    // Empty C++ array edge case
+    test(CollectionAndDelimiter(std::array<int, 0>{}, ","), "");
+    {
+        // C-style array
+        char letters[4]{'w', 'a', 's', 'd'};
+        test(CollectionAndDelimiter(letters, std::to_string(0)), "w0a0s0d");
+    }
+    {
+        // Auto sized C-style array
+        std::string words[]{"one", "two", "three", "four"};
+        test(CollectionAndDelimiter(words, "\n"), "one\ntwo\nthree\nfour");
+    }
+    {
+        // One item C-style array edge case
+        std::string words[]{"thing"};
+        test(CollectionAndDelimiter(words, "\n"), "thing");
+    }
+    // Initializer list
+    test(CollectionAndDelimiter(std::initializer_list<size_t>{19, 25}, "+"), "19+25");
+    // vector
+    test(CollectionAndDelimiter(std::vector<int>{0, 42}, std::to_string(99)), "09942");
+    // vector with one item edge case
+    test(CollectionAndDelimiter(std::vector<std::string>{"master"}, "xxx"), "master");
+    // vector with one non-trivial streamable item edge case
+    test(
+        CollectionAndDelimiter(std::vector<uint256>{uint256{1}}, "xxx"),
+        "0000000000000000000000000000000000000000000000000000000000000001");
+    // empty vector edge case
+    test(CollectionAndDelimiter(std::vector<uint256>{}, ","), "");
+    // C-style string
+    test(CollectionAndDelimiter("string", " "), "s t r i n g");
+    // Empty C-style string edge case
+    test(CollectionAndDelimiter("", "*"), "");
+    // Single char C-style string edge case
+    test(CollectionAndDelimiter("x", "*"), "x");
+    // std::string
+    test(CollectionAndDelimiter(std::string{"string"}, "-"), "s-t-r-i-n-g");
+    // Empty std::string edge case
+    test(CollectionAndDelimiter(std::string{""}, "*"), "");
+    // Single char std::string edge case
+    test(CollectionAndDelimiter(std::string{"y"}, "*"), "y");
+}
+
+}  // namespace xrpl::test

src/tests/libxrpl/helpers/TxTest.cpp

@@ -80,7 +80,9 @@ TxTest::TxTest(std::optional<FeatureBitset> features)
         std::vector<uint256>{featureSet_.begin(), featureSet_.end()},
         registry_.getNodeFamily());
 
-    // Initialize time from the genesis ledger
+    // Initialize time from the genesis ledger.  closedLedger_ is created above
+    // in the body, so this cannot be a member initializer.
+    // NOLINTNEXTLINE(cppcoreguidelines-prefer-member-initializer)
     now_ = closedLedger_->header().closeTime;
 
     // Create an open view on top of the genesis ledger

src/tests/libxrpl/json/Value.cpp

@@ -13,6 +13,7 @@
 #include <exception>
 #include <limits>
 #include <numbers>
+#include <optional>
 #include <regex>
 #include <sstream>
 #include <string>
@@ -592,6 +593,57 @@ TEST(json_value, bad_json)
     EXPECT_TRUE(r.parse(s, j));
 }
 
+namespace {
+
+std::optional<json::Value>
+parseValue(std::string const& doc)
+{
+    json::Value j;
+    json::Reader r;
+    if (!r.parse("{\"v\":" + doc + "}", j))
+        return std::nullopt;
+    return j["v"];
+}
+
+}  // namespace
+
+TEST(json_value, parse_double_valid)
+{
+    // 1e300 is large but still representable, so it parses (unlike the out-of-range cases below).
+    for (auto const& [text, expected] :
+         {std::pair{"2.5", 2.5},
+          std::pair{"-3.25e2", -325.0},
+          std::pair{"0.0", 0.0},
+          std::pair{"1E3", 1000.0},
+          std::pair{"-0.5e-1", -0.05},
+          std::pair{"1e300", 1e300}})
+    {
+        auto const v = parseValue(text);
+        ASSERT_TRUE(v.has_value()) << text;
+        // NOLINTBEGIN(bugprone-unchecked-optional-access)
+        EXPECT_TRUE(v->isDouble()) << text;
+        EXPECT_EQ(v->asDouble(), expected) << text;
+        // NOLINTEND(bugprone-unchecked-optional-access)
+    }
+}
+
+TEST(json_value, parse_double_out_of_range)
+{
+    // Magnitudes with no finite double representation are rejected.
+    for (char const* oor : {"1e400", "-1e400", "0.001e500", "1e-400", "-1e-400", "123e-500"})
+        EXPECT_FALSE(parseValue(oor).has_value()) << oor;
+}
+
+TEST(json_value, parse_double_malformed)
+{
+    // readNumber() collects any run of digits and '.eE+-' into a single Double
+    // token, so these malformed tokens reach decodeDouble. Each has a valid
+    // leading prefix that from_chars would accept on its own; requiring the
+    // entire token be consumed rejects them instead of silently truncating.
+    for (char const* bad : {"1+2", "1-2", "1.2.3", "1e5e6", "1..2", "++5", "1e", "1e+", ".", "-"})
+        EXPECT_FALSE(parseValue(bad).has_value()) << bad;
+}
+
 TEST(json_value, edge_cases)
 {
     std::uint32_t const maxUInt = std::numeric_limits<std::uint32_t>::max();

src/tests/libxrpl/resource/Logic.cpp

@@ -0,0 +1,241 @@
+#include <xrpl/resource/detail/Logic.h>
+
+#include <xrpl/basics/Log.h>
+#include <xrpl/basics/chrono.h>
+#include <xrpl/basics/random.h>
+#include <xrpl/beast/insight/NullCollector.h>
+#include <xrpl/beast/net/IPAddressV4.h>
+#include <xrpl/beast/utility/Journal.h>
+#include <xrpl/resource/Charge.h>
+#include <xrpl/resource/Consumer.h>
+#include <xrpl/resource/Disposition.h>
+#include <xrpl/resource/Gossip.h>
+#include <xrpl/resource/detail/Tuning.h>
+
+#include <boost/utility/base_from_member.hpp>
+
+#include <gtest/gtest.h>
+#include <helpers/TestSink.h>
+
+#include <chrono>
+#include <cstdint>
+#include <string>
+
+namespace xrpl::Resource {
+
+class ResourceManagerTest : public ::testing::Test
+{
+protected:
+    beast::Journal const j_{TestSink::instance()};
+
+    class TestLogic : private boost::base_from_member<TestStopwatch>, public Logic
+    {
+    private:
+        using clock_type = boost::base_from_member<TestStopwatch>;
+
+    public:
+        explicit TestLogic(beast::Journal journal)
+            : Logic(beast::insight::NullCollector::make(), member, journal)
+        {
+        }
+
+        void
+        advance()
+        {
+            ++member;
+        }
+
+        TestStopwatch&
+        clock()
+        {
+            return member;
+        }
+    };
+
+    //--------------------------------------------------------------------------
+
+    static void
+    populateGossip(Gossip& gossip)
+    {
+        std::uint8_t const v(10 + randInt(9));
+        std::uint8_t const n(10 + randInt(9));
+        gossip.items.reserve(n);
+        for (std::uint8_t i = 0; i < n; ++i)
+        {
+            Gossip::Item item;
+            item.balance = 100 + randInt(499);
+            beast::IP::AddressV4::bytes_type const d = {{
+                192,
+                0,
+                2,
+                static_cast<std::uint8_t>(v + i),
+            }};
+            item.address = beast::IP::Endpoint{beast::IP::AddressV4{d}};
+            gossip.items.push_back(item);
+        }
+    }
+};
+
+TEST_F(ResourceManagerTest, limited_warn_drop)
+{
+    TestLogic logic{j_};
+
+    Charge const fee{kDropThreshold + 1};
+    beast::IP::Endpoint const addr{beast::IP::Endpoint::fromString("192.0.2.2")};
+
+    {
+        Consumer c{logic.newInboundEndpoint(addr)};
+
+        // Create load until we get a warning
+        int n = 10000;
+        bool warned = false;
+
+        while (--n >= 0)
+        {
+            if (c.charge(fee) == Disposition::Warn)
+            {
+                warned = true;
+                break;
+            }
+            ++logic.clock();
+        }
+
+        ASSERT_TRUE(warned) << "Loop count exceeded without warning";
+
+        // Create load until we get dropped
+        bool dropped = false;
+        while (--n >= 0)
+        {
+            if (c.charge(fee) == Disposition::Drop)
+            {
+                dropped = true;
+                // Disconnect abusive Consumer
+                EXPECT_TRUE(c.disconnect(j_));
+                break;
+            }
+            ++logic.clock();
+        }
+
+        ASSERT_TRUE(dropped) << "Loop count exceeded without dropping";
+    }
+
+    // Make sure the consumer is on the blacklist for a while.
+    {
+        Consumer const c{logic.newInboundEndpoint(addr)};
+        logic.periodicActivity();
+        EXPECT_EQ(c.disposition(), Disposition::Drop) << "Dropped consumer not put on blacklist";
+    }
+
+    // Makes sure the Consumer is eventually removed from blacklist
+    bool readmitted = false;
+    {
+        using namespace std::chrono_literals;
+        // Give Consumer time to become readmitted.  Should never
+        // exceed expiration time.
+        auto n = kSecondsUntilExpiration + 1s;
+        while (--n > 0s)
+        {
+            ++logic.clock();
+            logic.periodicActivity();
+            Consumer const c{logic.newInboundEndpoint(addr)};
+            if (c.disposition() != Disposition::Drop)
+            {
+                readmitted = true;
+                break;
+            }
+        }
+    }
+    EXPECT_TRUE(readmitted) << "Dropped Consumer left on blacklist too long";
+}
+
+TEST_F(ResourceManagerTest, unlimited_warn_drop)
+{
+    TestLogic logic{j_};
+
+    Charge const fee{kDropThreshold + 1};
+    beast::IP::Endpoint const addr{beast::IP::Endpoint::fromString("192.0.2.2")};
+    Consumer c{logic.newUnlimitedEndpoint(addr)};
+
+    // Create load until we get a warning
+    int n = 10000;
+    bool warned = false;
+
+    while (--n >= 0)
+    {
+        if (c.charge(fee) == Disposition::Warn)
+        {
+            warned = true;
+            break;
+        }
+        ++logic.clock();
+    }
+
+    EXPECT_FALSE(warned) << "Should loop forever with no warning";
+}
+
+TEST_F(ResourceManagerTest, charges)
+{
+    TestLogic logic{j_};
+
+    {
+        beast::IP::Endpoint const address{beast::IP::Endpoint::fromString("192.0.2.1")};
+        Consumer c{logic.newInboundEndpoint(address)};
+        Charge const fee{1000};
+        JLOG(j_.info()) << "Charging " << c.toString() << " " << fee << " per second";
+        c.charge(fee);
+        for (int i = 0; i < 128; ++i)
+        {
+            JLOG(j_.info()) << "Time= " << logic.clock().now().time_since_epoch().count()
+                            << ", Balance = " << c.balance();
+            logic.advance();
+        }
+    }
+
+    {
+        beast::IP::Endpoint const address{beast::IP::Endpoint::fromString("192.0.2.2")};
+        Consumer c{logic.newInboundEndpoint(address)};
+        Charge const fee{1000};
+        JLOG(j_.info()) << "Charging " << c.toString() << " " << fee << " per second";
+        for (int i = 0; i < 128; ++i)
+        {
+            c.charge(fee);
+            JLOG(j_.info()) << "Time= " << logic.clock().now().time_since_epoch().count()
+                            << ", Balance = " << c.balance();
+            logic.advance();
+        }
+    }
+}
+
+TEST_F(ResourceManagerTest, imports)
+{
+    TestLogic logic{j_};
+
+    Gossip g[5];
+
+    for (auto& i : g)
+        populateGossip(i);
+
+    for (int i = 0; i < 5; ++i)
+        logic.importConsumers(std::to_string(i), g[i]);
+}
+
+TEST_F(ResourceManagerTest, import)
+{
+    TestLogic logic{j_};
+
+    Gossip g;
+    Gossip::Item item;
+    item.balance = 100;
+    beast::IP::AddressV4::bytes_type const d = {{
+        192,
+        0,
+        2,
+        1,
+    }};
+    item.address = beast::IP::Endpoint{beast::IP::AddressV4{d}};
+    g.items.push_back(item);
+
+    logic.importConsumers("g", g);
+}
+
+}  // namespace xrpl::Resource

src/tests/libxrpl/shamap/FetchPack.cpp

@@ -0,0 +1,22 @@
+#include <xrpl/beast/utility/Journal.h>
+#include <xrpl/shamap/SHAMap.h>
+#include <xrpl/shamap/SHAMapMissingNode.h>
+
+#include <gtest/gtest.h>
+#include <helpers/TestSink.h>
+#include <shamap/common.h>
+
+#include <memory>
+
+namespace xrpl::tests {
+
+TEST(FetchPackTest, construct_table)
+{
+    beast::Journal const j{TestSink::instance()};
+    TestNodeFamily f{j};
+    std::shared_ptr<SHAMap> const t1{std::make_shared<SHAMap>(SHAMapType::FREE, f)};
+
+    EXPECT_NE(t1, nullptr);
+}
+
+}  // namespace xrpl::tests

src/tests/libxrpl/shamap/SHAMap.cpp

@@ -0,0 +1,349 @@
+#include <xrpl/shamap/SHAMap.h>
+
+#include <xrpl/basics/Blob.h>
+#include <xrpl/basics/Buffer.h>
+#include <xrpl/basics/SHAMapHash.h>
+#include <xrpl/basics/base_uint.h>
+#include <xrpl/beast/utility/Journal.h>
+#include <xrpl/beast/utility/Zero.h>
+#include <xrpl/shamap/SHAMapInnerNode.h>
+#include <xrpl/shamap/SHAMapItem.h>
+#include <xrpl/shamap/SHAMapLeafNode.h>
+#include <xrpl/shamap/SHAMapMissingNode.h>
+#include <xrpl/shamap/SHAMapTreeNode.h>
+
+#include <gtest/gtest.h>
+#include <helpers/TestSink.h>
+#include <shamap/common.h>
+
+#include <algorithm>
+#include <array>
+#include <cstddef>
+#include <cstdint>
+#include <memory>
+#include <string>
+#include <string_view>
+#include <type_traits>
+#include <utility>
+#include <vector>
+
+namespace xrpl::tests {
+
+#ifndef __INTELLISENSE__
+static_assert(std::is_nothrow_destructible<SHAMap>{});
+static_assert(!std::is_default_constructible<SHAMap>{});
+static_assert(!std::is_copy_constructible<SHAMap>{});
+static_assert(!std::is_copy_assignable<SHAMap>{});
+static_assert(!std::is_move_constructible<SHAMap>{});
+static_assert(!std::is_move_assignable<SHAMap>{});
+
+static_assert(std::is_nothrow_destructible<SHAMap::ConstIterator>{});
+static_assert(std::is_copy_constructible<SHAMap::ConstIterator>{});
+static_assert(std::is_copy_assignable<SHAMap::ConstIterator>{});
+static_assert(std::is_move_constructible<SHAMap::ConstIterator>{});
+static_assert(std::is_move_assignable<SHAMap::ConstIterator>{});
+
+static_assert(std::is_nothrow_destructible<SHAMapItem>{});
+static_assert(!std::is_default_constructible<SHAMapItem>{});
+static_assert(!std::is_copy_constructible<SHAMapItem>{});
+
+static_assert(std::is_nothrow_destructible<SHAMapNodeID>{});
+static_assert(std::is_default_constructible<SHAMapNodeID>{});
+static_assert(std::is_copy_constructible<SHAMapNodeID>{});
+static_assert(std::is_copy_assignable<SHAMapNodeID>{});
+static_assert(std::is_move_constructible<SHAMapNodeID>{});
+static_assert(std::is_move_assignable<SHAMapNodeID>{});
+
+static_assert(std::is_nothrow_destructible<SHAMapHash>{});
+static_assert(std::is_default_constructible<SHAMapHash>{});
+static_assert(std::is_copy_constructible<SHAMapHash>{});
+static_assert(std::is_copy_assignable<SHAMapHash>{});
+static_assert(std::is_move_constructible<SHAMapHash>{});
+static_assert(std::is_move_assignable<SHAMapHash>{});
+
+static_assert(std::is_nothrow_destructible<SHAMapTreeNode>{});
+static_assert(!std::is_default_constructible<SHAMapTreeNode>{});
+static_assert(!std::is_copy_constructible<SHAMapTreeNode>{});
+static_assert(!std::is_copy_assignable<SHAMapTreeNode>{});
+static_assert(!std::is_move_constructible<SHAMapTreeNode>{});
+static_assert(!std::is_move_assignable<SHAMapTreeNode>{});
+
+static_assert(std::is_nothrow_destructible<SHAMapInnerNode>{});
+static_assert(!std::is_default_constructible<SHAMapInnerNode>{});
+static_assert(!std::is_copy_constructible<SHAMapInnerNode>{});
+static_assert(!std::is_copy_assignable<SHAMapInnerNode>{});
+static_assert(!std::is_move_constructible<SHAMapInnerNode>{});
+static_assert(!std::is_move_assignable<SHAMapInnerNode>{});
+
+static_assert(std::is_nothrow_destructible<SHAMapLeafNode>{});
+static_assert(!std::is_default_constructible<SHAMapLeafNode>{});
+static_assert(!std::is_copy_constructible<SHAMapLeafNode>{});
+static_assert(!std::is_copy_assignable<SHAMapLeafNode>{});
+static_assert(!std::is_move_constructible<SHAMapLeafNode>{});
+static_assert(!std::is_move_assignable<SHAMapLeafNode>{});
+#endif
+
+inline bool
+operator!=(SHAMapItem const& a, SHAMapItem const& b)
+{
+    return a.key() != b.key();
+}
+
+struct SHAMapBackingMode
+{
+    bool backed;
+    std::string_view testName;
+};
+
+constexpr SHAMapBackingMode kBackedMode{.backed = true, .testName = "backed"};
+constexpr SHAMapBackingMode kUnbackedMode{.backed = false, .testName = "unbacked"};
+
+std::string
+shamapBackingModeName(::testing::TestParamInfo<SHAMapBackingMode> const& info)
+{
+    return std::string{info.param.testName};
+}
+
+class SHAMapTest : public ::testing::TestWithParam<SHAMapBackingMode>
+{
+protected:
+    beast::Journal const j_{TestSink::instance()};
+
+    static Buffer
+    intToVuc(std::uint8_t v)
+    {
+        Buffer vuc{32};
+        std::fill_n(vuc.data(), vuc.size(), v);
+        return vuc;
+    }
+};
+
+TEST_P(SHAMapTest, add_traverse_snapshot_build_tear_and_iterate)
+{
+    auto const testMode = GetParam();
+    tests::TestNodeFamily f{j_};
+
+    // kH3 and kH4 differ only in the leaf, same terminal node (level 19)
+    constexpr uint256 kH1("092891fe4ef6cee585fdc6fda0e09eb4d386363158ec3321b8123e5a772c6ca7");
+    constexpr uint256 kH2("436ccbac3347baa1f1e53baeef1f43334da88f1f6d70d963b833afd6dfa289fe");
+    constexpr uint256 kH3("b92891fe4ef6cee585fdc6fda1e09eb4d386363158ec3321b8123e5a772c6ca8");
+    constexpr uint256 kH4("b92891fe4ef6cee585fdc6fda2e09eb4d386363158ec3321b8123e5a772c6ca8");
+
+    SHAMap sMap{SHAMapType::FREE, f};
+    sMap.invariants();
+    if (!testMode.backed)
+        sMap.setUnbacked();
+
+    auto i1 = makeShamapitem(kH1, intToVuc(1));
+    auto i2 = makeShamapitem(kH2, intToVuc(2));
+    auto i3 = makeShamapitem(kH3, intToVuc(3));
+    auto i4 = makeShamapitem(kH4, intToVuc(4));
+
+    EXPECT_TRUE(sMap.addItem(SHAMapNodeType::TnTransactionNm, makeShamapitem(*i2))) << "no add";
+    sMap.invariants();
+    EXPECT_TRUE(sMap.addItem(SHAMapNodeType::TnTransactionNm, makeShamapitem(*i1))) << "no add";
+    sMap.invariants();
+
+    auto i = sMap.begin();
+    auto e = sMap.end();
+    EXPECT_FALSE(i == e || (*i != *i1)) << "bad traverse";
+    ++i;
+    EXPECT_FALSE(i == e || (*i != *i2)) << "bad traverse";
+    ++i;
+    EXPECT_EQ(i, e) << "bad traverse";
+    sMap.addItem(SHAMapNodeType::TnTransactionNm, makeShamapitem(*i4));
+    sMap.invariants();
+    sMap.delItem(i2->key());
+    sMap.invariants();
+    sMap.addItem(SHAMapNodeType::TnTransactionNm, makeShamapitem(*i3));
+    sMap.invariants();
+    i = sMap.begin();
+    e = sMap.end();
+    EXPECT_FALSE(i == e || (*i != *i1)) << "bad traverse";
+    ++i;
+    EXPECT_FALSE(i == e || (*i != *i3)) << "bad traverse";
+    ++i;
+    EXPECT_FALSE(i == e || (*i != *i4)) << "bad traverse";
+    ++i;
+    EXPECT_EQ(i, e) << "bad traverse";
+
+    SHAMapHash const mapHash = sMap.getHash();
+    std::shared_ptr<SHAMap> const map2 = sMap.snapShot(false);
+    map2->invariants();
+    EXPECT_EQ(sMap.getHash(), mapHash) << "bad snapshot";
+    EXPECT_EQ(map2->getHash(), mapHash) << "bad snapshot";
+
+    SHAMap::Delta delta;
+    ASSERT_TRUE(sMap.compare(*map2, delta, 100));
+    EXPECT_TRUE(delta.empty());
+
+    EXPECT_TRUE(sMap.delItem(sMap.begin()->key())) << "bad mod";
+    sMap.invariants();
+    EXPECT_NE(sMap.getHash(), mapHash) << "bad snapshot";
+    EXPECT_EQ(map2->getHash(), mapHash) << "bad snapshot";
+
+    ASSERT_TRUE(sMap.compare(*map2, delta, 100));
+    ASSERT_EQ(delta.size(), 1);
+    EXPECT_EQ(delta.begin()->first, kH1);
+    EXPECT_EQ(delta.begin()->second.first, nullptr);
+    ASSERT_NE(delta.begin()->second.second, nullptr);
+    EXPECT_EQ(delta.begin()->second.second->key(), kH1);
+
+    sMap.dump();
+    {
+        constexpr std::array kKeys{
+            uint256{"b92891fe4ef6cee585fdc6fda1e09eb4d386363158ec3321b8123e5a772c6ca8"},
+            uint256{"b92881fe4ef6cee585fdc6fda1e09eb4d386363158ec3321b8123e5a772c6ca8"},
+            uint256{"b92691fe4ef6cee585fdc6fda1e09eb4d386363158ec3321b8123e5a772c6ca8"},
+            uint256{"b92791fe4ef6cee585fdc6fda1e09eb4d386363158ec3321b8123e5a772c6ca8"},
+            uint256{"b91891fe4ef6cee585fdc6fda1e09eb4d386363158ec3321b8123e5a772c6ca8"},
+            uint256{"b99891fe4ef6cee585fdc6fda1e09eb4d386363158ec3321b8123e5a772c6ca8"},
+            uint256{"f22891fe4ef6cee585fdc6fda1e09eb4d386363158ec3321b8123e5a772c6ca8"},
+            uint256{"292891fe4ef6cee585fdc6fda1e09eb4d386363158ec3321b8123e5a772c6ca8"},
+        };
+
+        constexpr std::array kHashes{
+            uint256{"B7387CFEA0465759ADC718E8C42B52D2309D179B326E239EB5075C64B6281F7F"},
+            uint256{"FBC195A9592A54AB44010274163CB6BA95F497EC5BA0A8831845467FB2ECE266"},
+            uint256{"4E7D2684B65DFD48937FFB775E20175C43AF0C94066F7D5679F51AE756795B75"},
+            uint256{"7A2F312EB203695FFD164E038E281839EEF06A1B99BFC263F3CECC6C74F93E07"},
+            uint256{"395A6691A372387A703FB0F2C6D2C405DAF307D0817F8F0E207596462B0E3A3E"},
+            uint256{"D044C0A696DE3169CC70AE216A1564D69DE96582865796142CE7D98A84D9DDE4"},
+            uint256{"76DCC77C4027309B5A91AD164083264D70B77B5E43E08AEDA5EBF94361143615"},
+            uint256{"DF4220E93ADC6F5569063A01B4DC79F8DB9553B6A3222ADE23DEA02BBE7230E5"},
+        };
+
+        SHAMap map{SHAMapType::FREE, f};
+        if (!testMode.backed)
+            map.setUnbacked();
+
+        EXPECT_EQ(map.getHash(), beast::kZero);
+        for (std::size_t k = 0; k < kKeys.size(); ++k)
+        {
+            EXPECT_TRUE(map.addItem(
+                SHAMapNodeType::TnTransactionNm,
+                makeShamapitem(kKeys[k], intToVuc(static_cast<std::uint8_t>(k)))));
+            EXPECT_EQ(map.getHash().asUInt256(), kHashes[k]);
+            map.invariants();
+        }
+        for (std::size_t k = kKeys.size(); k-- > 0;)
+        {
+            EXPECT_EQ(map.getHash().asUInt256(), kHashes[k]);
+            EXPECT_TRUE(map.delItem(kKeys[k]));
+            map.invariants();
+        }
+        EXPECT_EQ(map.getHash(), beast::kZero);
+    }
+
+    {
+        constexpr std::array kKeys{
+            uint256{"f22891fe4ef6cee585fdc6fda1e09eb4d386363158ec3321b8123e5a772c6ca8"},
+            uint256{"b99891fe4ef6cee585fdc6fda1e09eb4d386363158ec3321b8123e5a772c6ca8"},
+            uint256{"b92891fe4ef6cee585fdc6fda1e09eb4d386363158ec3321b8123e5a772c6ca8"},
+            uint256{"b92881fe4ef6cee585fdc6fda1e09eb4d386363158ec3321b8123e5a772c6ca8"},
+            uint256{"b92791fe4ef6cee585fdc6fda1e09eb4d386363158ec3321b8123e5a772c6ca8"},
+            uint256{"b92691fe4ef6cee585fdc6fda1e09eb4d386363158ec3321b8123e5a772c6ca8"},
+            uint256{"b91891fe4ef6cee585fdc6fda1e09eb4d386363158ec3321b8123e5a772c6ca8"},
+            uint256{"292891fe4ef6cee585fdc6fda1e09eb4d386363158ec3321b8123e5a772c6ca8"},
+        };
+
+        tests::TestNodeFamily tf{j_};
+        SHAMap map{SHAMapType::FREE, tf};
+        if (!testMode.backed)
+            map.setUnbacked();
+        for (auto const& k : kKeys)
+        {
+            map.addItem(SHAMapNodeType::TnTransactionNm, makeShamapitem(k, intToVuc(0)));
+            map.invariants();
+        }
+
+        int h = 7;
+        for (auto const& k : map)
+        {
+            EXPECT_EQ(k.key(), kKeys[h]);
+            --h;
+        }
+    }
+}
+
+INSTANTIATE_TEST_SUITE_P(
+    BackingMode,
+    SHAMapTest,
+    ::testing::Values(kBackedMode, kUnbackedMode),
+    shamapBackingModeName);
+
+class SHAMapPathProof : public ::testing::Test
+{
+protected:
+    beast::Journal const j_{TestSink::instance()};
+};
+
+TEST_F(SHAMapPathProof, verify_proof_path)
+{
+    tests::TestNodeFamily tf{j_};
+    SHAMap map{SHAMapType::FREE, tf};
+    map.setUnbacked();
+
+    uint256 key;
+    uint256 rootHash;
+    std::vector<Blob> goodPath;
+
+    for (unsigned char c = 1; c < 100; ++c)
+    {
+        uint256 k(c);
+        map.addItem(SHAMapNodeType::TnAccountState, makeShamapitem(k, Slice{k.data(), k.size()}));
+        map.invariants();
+
+        auto root = map.getHash().asUInt256();
+        auto path = map.getProofPath(k);
+        if (!path)
+        {
+            ADD_FAILURE() << "Missing proof path";
+            return;
+        }
+        auto& proofPath = *path;
+
+        EXPECT_TRUE(map.verifyProofPath(root, k, proofPath));
+        if (c == 1)
+        {
+            // extra node
+            proofPath.insert(proofPath.begin(), proofPath.front());
+            EXPECT_FALSE(map.verifyProofPath(root, k, proofPath));
+            // wrong key
+            uint256 const wrongKey(c + 1);
+            EXPECT_FALSE(map.getProofPath(wrongKey));
+        }
+        if (c == 99)
+        {
+            key = k;
+            rootHash = root;
+            goodPath = std::move(proofPath);
+        }
+    }
+
+    // still good
+    EXPECT_TRUE(map.verifyProofPath(rootHash, key, goodPath));
+    // empty path
+    std::vector<Blob> badPath;
+    EXPECT_FALSE(map.verifyProofPath(rootHash, key, badPath));
+    // too long
+    badPath = goodPath;
+    badPath.push_back(goodPath.back());
+    EXPECT_FALSE(map.verifyProofPath(rootHash, key, badPath));
+    // bad node
+    badPath.clear();
+    badPath.emplace_back(100, 100);
+    EXPECT_FALSE(map.verifyProofPath(rootHash, key, badPath));
+    // bad node type
+    badPath.clear();
+    badPath.push_back(goodPath.front());
+    badPath.front().back()--;  // change node type
+    EXPECT_FALSE(map.verifyProofPath(rootHash, key, badPath));
+    // all inner
+    badPath.clear();
+    badPath = goodPath;
+    badPath.erase(badPath.begin());
+    EXPECT_FALSE(map.verifyProofPath(rootHash, key, badPath));
+}
+
+}  // namespace xrpl::tests

src/tests/libxrpl/shamap/SHAMapSync.cpp

@@ -0,0 +1,170 @@
+#include <xrpl/basics/Blob.h>
+#include <xrpl/basics/SHAMapHash.h>
+#include <xrpl/basics/Slice.h>
+#include <xrpl/basics/base_uint.h>
+#include <xrpl/basics/random.h>
+#include <xrpl/beast/utility/Journal.h>
+#include <xrpl/beast/xor_shift_engine.h>
+#include <xrpl/protocol/Serializer.h>
+#include <xrpl/shamap/SHAMap.h>
+#include <xrpl/shamap/SHAMapItem.h>
+#include <xrpl/shamap/SHAMapMissingNode.h>
+#include <xrpl/shamap/SHAMapTreeNode.h>
+
+#include <boost/smart_ptr/intrusive_ptr.hpp>
+
+#include <gtest/gtest.h>
+#include <helpers/TestSink.h>
+#include <shamap/common.h>
+
+#include <chrono>
+#include <cstdint>
+#include <list>
+#include <utility>
+#include <vector>
+
+namespace xrpl::tests {
+
+class SHAMapSyncTest : public ::testing::Test
+{
+protected:
+    beast::Journal const j_{TestSink::instance()};
+    beast::xor_shift_engine eng_;
+
+    boost::intrusive_ptr<SHAMapItem>
+    makeRandomAS()
+    {
+        Serializer s;
+
+        for (int d = 0; d < 3; ++d)
+            s.add32(randInt<std::uint32_t>(eng_));
+        return makeShamapitem(s.getSHA512Half(), s.slice());
+    }
+
+    bool
+    confuseMap(SHAMap& map, int count)
+    {
+        // add a bunch of random states to a map, then remove them
+        // map should be the same
+        SHAMapHash const beforeHash = map.getHash();
+
+        std::list<uint256> items;
+
+        for (int i = 0; i < count; ++i)
+        {
+            auto item = makeRandomAS();
+            items.push_back(item->key());
+
+            if (!map.addItem(SHAMapNodeType::TnAccountState, item))
+            {
+                ADD_FAILURE() << "Unable to add item to map";
+                return false;
+            }
+        }
+
+        for (auto const& item : items)
+        {
+            if (!map.delItem(item))
+            {
+                ADD_FAILURE() << "Unable to remove item from map";
+                return false;
+            }
+        }
+
+        if (beforeHash != map.getHash())
+        {
+            ADD_FAILURE() << "Hashes do not match " << beforeHash << " " << map.getHash();
+            return false;
+        }
+
+        return true;
+    }
+};
+
+TEST_F(SHAMapSyncTest, sync)
+{
+    TestNodeFamily f{j_}, f2{j_};
+    SHAMap source{SHAMapType::FREE, f};
+    SHAMap destination{SHAMapType::FREE, f2};
+
+    int const items = 10000;
+    for (int i = 0; i < items; ++i)
+    {
+        source.addItem(SHAMapNodeType::TnAccountState, makeRandomAS());
+        if (i % 100 == 0)
+            source.invariants();
+    }
+
+    source.invariants();
+    ASSERT_TRUE(confuseMap(source, 500));
+    source.invariants();
+
+    source.setImmutable();
+
+    int count = 0;
+    source.visitLeaves([&count]([[maybe_unused]] auto const& item) { ++count; });
+    EXPECT_EQ(count, items);
+
+    std::vector<SHAMapMissingNode> missingNodes;
+    source.walkMap(missingNodes, 2048);
+    EXPECT_TRUE(missingNodes.empty());
+
+    destination.setSynching();
+
+    {
+        std::vector<std::pair<SHAMapNodeID, Blob>> a;
+
+        ASSERT_TRUE(source.getNodeFat(SHAMapNodeID(), a, randBool(eng_), randInt(eng_, 2)));
+
+        ASSERT_FALSE(a.empty()) << "NodeSize";
+
+        ASSERT_TRUE(
+            destination.addRootNode(source.getHash(), makeSlice(a[0].second), nullptr).isGood());
+    }
+
+    do
+    {
+        f.clock().advance(std::chrono::seconds(1));
+
+        // get the list of nodes we know we need
+        auto nodesMissing = destination.getMissingNodes(2048, nullptr);
+
+        if (nodesMissing.empty())
+            break;
+
+        // get as many nodes as possible based on this information
+        std::vector<std::pair<SHAMapNodeID, Blob>> b;
+
+        for (auto& it : nodesMissing)
+        {
+            // Keep failures fatal here because this loop is data-dependent.
+            // non-deterministic number of times and the number of tests run
+            // should be deterministic
+            if (!source.getNodeFat(it.first, b, randBool(eng_), randInt(eng_, 2)))
+                FAIL() << "Unable to fetch node";
+        }
+
+        // Keep failures fatal here because this loop is data-dependent.
+        // non-deterministic number of times and the number of tests run
+        // should be deterministic
+        if (b.empty())
+            FAIL() << "No nodes returned";
+
+        for (auto const& i : b)
+        {
+            // Keep failures fatal here because this loop is data-dependent.
+            // non-deterministic number of times and the number of tests run
+            // should be deterministic
+            if (!destination.addKnownNode(i.first, makeSlice(i.second), nullptr).isUseful())
+                FAIL() << "Known node was not useful";
+        }
+    } while (true);
+
+    destination.clearSynching();
+
+    EXPECT_TRUE(source.deepCompare(destination));
+
+    destination.invariants();
+}
+
+}  // namespace xrpl::tests

src/tests/libxrpl/shamap/common.h

@@ -0,0 +1,123 @@
+#pragma once
+
+#include <xrpl/basics/ByteUtilities.h>
+#include <xrpl/basics/base_uint.h>
+#include <xrpl/basics/chrono.h>
+#include <xrpl/basics/contract.h>
+#include <xrpl/beast/utility/Journal.h>
+#include <xrpl/config/BasicConfig.h>
+#include <xrpl/config/Constants.h>
+#include <xrpl/nodestore/Database.h>
+#include <xrpl/nodestore/DummyScheduler.h>
+#include <xrpl/nodestore/Manager.h>
+#include <xrpl/shamap/Family.h>
+#include <xrpl/shamap/FullBelowCache.h>
+#include <xrpl/shamap/TreeNodeCache.h>
+
+#include <chrono>
+#include <cstdint>
+#include <memory>
+#include <stdexcept>
+
+namespace xrpl::tests {
+
+class TestNodeFamily : public Family
+{
+private:
+    std::unique_ptr<NodeStore::Database> db_;
+
+    std::shared_ptr<FullBelowCache> fbCache_;
+    std::shared_ptr<TreeNodeCache> tnCache_;
+
+    TestStopwatch clock_;
+    NodeStore::DummyScheduler scheduler_;
+
+    beast::Journal const j_;
+
+public:
+    TestNodeFamily(beast::Journal j)
+        : fbCache_(std::make_shared<FullBelowCache>("App family full below cache", clock_, j))
+        , tnCache_(
+              std::make_shared<TreeNodeCache>(
+                  "App family tree node cache",
+                  65536,
+                  std::chrono::minutes{1},
+                  clock_,
+                  j))
+        , j_(j)
+    {
+        Section testSection;
+        testSection.set(Keys::kType, "memory");
+        testSection.set(Keys::kPath, "SHAMap_test");
+        db_ = NodeStore::Manager::instance().makeDatabase(
+            megabytes(4), scheduler_, 1, testSection, j);
+    }
+
+    NodeStore::Database&
+    db() override
+    {
+        return *db_;
+    }
+
+    [[nodiscard]] NodeStore::Database const&
+    db() const override
+    {
+        return *db_;
+    }
+
+    beast::Journal const&
+    journal() override
+    {
+        return j_;
+    }
+
+    std::shared_ptr<FullBelowCache>
+    getFullBelowCache() override
+    {
+        return fbCache_;
+    }
+
+    std::shared_ptr<TreeNodeCache>
+    getTreeNodeCache() override
+    {
+        return tnCache_;
+    }
+
+    void
+    sweep() override
+    {
+        fbCache_->sweep();
+        tnCache_->sweep();
+    }
+
+    void
+    missingNodeAcquireBySeq(
+        [[maybe_unused]] std::uint32_t refNum,
+        [[maybe_unused]] uint256 const& nodeHash) override
+    {
+        Throw<std::runtime_error>("missing node");
+    }
+
+    void
+    missingNodeAcquireByHash(
+        [[maybe_unused]] uint256 const& refHash,
+        [[maybe_unused]] std::uint32_t refNum) override
+    {
+        Throw<std::runtime_error>("missing node");
+    }
+
+    void
+    reset() override
+    {
+        (*fbCache_).reset();
+        (*tnCache_).reset();
+    }
+
+    TestStopwatch&
+    clock()
+    {
+        return clock_;
+    }
+};
+
+}  // namespace xrpl::tests