LoanTestBase.h

#pragma once
 
#include <xrpl/beast/unit_test/suite.h>
//
#include <test/jtx/Account.h>
#include <test/jtx/Env.h>
#include <test/jtx/JTx.h>
#include <test/jtx/TestHelpers.h>
#include <test/jtx/amount.h>
#include <test/jtx/fee.h>
#include <test/jtx/flags.h>
#include <test/jtx/mpt.h>
#include <test/jtx/multisign.h>
#include <test/jtx/pay.h>
#include <test/jtx/sig.h>
#include <test/jtx/tags.h>
#include <test/jtx/ter.h>
#include <test/jtx/trust.h>
#include <test/jtx/vault.h>
 
#include <xrpld/rpc/detail/Handler.h>
 
#include <xrpl/basics/Number.h>
#include <xrpl/basics/base_uint.h>
#include <xrpl/basics/chrono.h>
#include <xrpl/beast/utility/Journal.h>
#include <xrpl/beast/utility/Zero.h>
#include <xrpl/json/json_value.h>
#include <xrpl/ledger/helpers/AccountRootHelpers.h>
#include <xrpl/ledger/helpers/LendingHelpers.h>
#include <xrpl/ledger/helpers/VaultHelpers.h>
#include <xrpl/protocol/Asset.h>
#include <xrpl/protocol/Feature.h>
#include <xrpl/protocol/Indexes.h>
#include <xrpl/protocol/Issue.h>
#include <xrpl/protocol/Keylet.h>
#include <xrpl/protocol/LedgerFormats.h>
#include <xrpl/protocol/MPTIssue.h>
#include <xrpl/protocol/Protocol.h>
#include <xrpl/protocol/SField.h>
#include <xrpl/protocol/STAmount.h>
#include <xrpl/protocol/SeqProxy.h>
#include <xrpl/protocol/TER.h>
#include <xrpl/protocol/TxFlags.h>
#include <xrpl/protocol/Units.h>
#include <xrpl/protocol/XRPAmount.h>
#include <xrpl/server/LoadFeeTrack.h>
#include <xrpl/tx/transactors/lending/LoanSet.h>
 
#include <algorithm>
#include <array>
#include <chrono>
#include <cstddef>
#include <cstdint>
#include <cstdlib>
#include <functional>
#include <initializer_list>
#include <optional>
#include <ostream>
#include <sstream>
#include <stdexcept>
#include <string>
#include <tuple>
#include <type_traits>
#include <utility>
#include <vector>
 
namespace xrpl::test {
 
class LoanTestBase : public beast::unit_test::Suite
{
protected:
    // Ensure that all the features needed for Lending Protocol are included,
    // even if they are set to unsupported.
    //
    // featureLendingProtocolV1_1 is excluded from the default set: it changes
    // Vault/LoanBroker accounting (AssetsTotal/DebtTotal/LossUnrealized), and
    // most of this file's tests assert whole-life-specific expected values
    // for those fields. Tests that specifically exercise the amendment opt
    // it back in explicitly (e.g. `all_ | featureLendingProtocolV1_1`).
    FeatureBitset const all_{jtx::testableAmendments() - featureLendingProtocolV1_1};
    std::string const iouCurrency_{"IOU"};
 
    struct BrokerParameters
    {
        Number vaultDeposit = 1'000'000;
        Number debtMax = 25'000;
        TenthBips32 coverRateMin = percentageToTenthBips(10);
        int coverDeposit = 1000;
        TenthBips16 managementFeeRate{100};
        TenthBips32 coverRateLiquidation = percentageToTenthBips(25);
        std::string data = {};  // NOLINT(readability-redundant-member-init)
        std::uint32_t flags = 0;
        // If set, the vault is created with this sfScale value. Useful for
        // tests that need finer loanScale to exercise rounding edge cases.
        std::optional<std::uint8_t> vaultScale =
            std::nullopt;  // NOLINT(readability-redundant-member-init)
        // Vault kind axis. When ClosedEnded, createVaultAndBroker sets sfSubscriptionDate /
        // sfRedemptionDate from env.now() using the offsets below and advances the ledger clock
        // past SubscriptionDate so the vault is in the Investment phase by the time the broker is
        // set up. Requires featureLendingProtocolV1_1.
        VaultKind vaultKind = VaultKind::OpenEnded;
        // Seconds past env.now() at which SubscriptionDate lands. Must be strictly positive
        // (VaultCreate::preclaim rejects SubscriptionDate <= parentCloseTime).
        std::uint32_t subscriptionOffset = 60;
        // Seconds between SubscriptionDate and RedemptionDate. Must be >= kMinInvestmentPeriod, <
        // kMaxInvestmentPeriod, and generous enough to fit any loan schedule the test runs
        // (finalPayment must be strictly before RedemptionDate). Default sized to comfortably
        // exceed any schedule realistic tests are likely to configure.
        std::uint32_t redemptionOffset = 10u * 365u * 24u * 60u * 60u;
        // When true, createVaultAndBroker skips its automatic clock advance past SubscriptionDate.
        // Useful for tests that need to observe the vault while it is still in the Subscription
        // phase. Ignored for open-ended vaults.
        bool skipPhaseAdvance = false;
 
        [[nodiscard]] Number
        maxCoveredLoanValue(Number const& currentDebt) const
        {
            NumberRoundModeGuard const mg(Number::RoundingMode::Downward);
            auto debtLimit = coverDeposit * kTenthBipsPerUnity.value() / coverRateMin.value();
 
            return debtLimit - currentDebt;
        }
 
        static BrokerParameters const&
        defaults()
        {
            static BrokerParameters const kResult{};
            return kResult;
        }
 
        // TODO: create an operator() which returns a transaction similar to
        // LoanParameters
    };
 
    struct BrokerInfo
    {
        jtx::PrettyAsset asset;
        uint256 brokerID;
        uint256 vaultID;
        BrokerParameters params;
        // Absolute dates resolved by createVaultAndBroker when params.vaultKind
        // is ClosedEnded; std::nullopt for open-ended vaults.
        std::optional<std::uint32_t> subscriptionDate;
        std::optional<std::uint32_t> redemptionDate;
        BrokerInfo(
            jtx::PrettyAsset const& asset,
            Keylet const& brokerKeylet,
            Keylet const& vaultKeylet,
            BrokerParameters p,
            std::optional<std::uint32_t> subscriptionDate = std::nullopt,
            std::optional<std::uint32_t> redemptionDate = std::nullopt)
            : asset(asset)
            , brokerID(brokerKeylet.key)
            , vaultID(vaultKeylet.key)
            , params(std::move(p))
            , subscriptionDate(subscriptionDate)
            , redemptionDate(redemptionDate)
        {
        }
 
        [[nodiscard]] Keylet
        brokerKeylet() const
        {
            return keylet::loanBroker(brokerID);
        }
        [[nodiscard]] Keylet
        vaultKeylet() const
        {
            return keylet::vault(vaultID);
        }
 
        [[nodiscard]] int
        vaultScale(jtx::Env const& env) const
        {
            using namespace jtx;
 
            auto const vaultSle = env.le(keylet::vault(vaultID));
            return getAssetsTotalScale(vaultSle);
        }
    };
 
    struct LoanParameters
    {
        // The account submitting the transaction. May be borrower or broker.
        jtx::Account account;
        // The counterparty. Should be the other of borrower or broker.
        jtx::Account counter;
        // Whether the counterparty is specified in the `counterparty` field, or
        // only signs.
        bool counterpartyExplicit = true;
        Number principalRequest;
        // NOLINTBEGIN(readability-redundant-member-init)
        std::optional<STAmount> setFee = std::nullopt;
        std::optional<Number> originationFee = std::nullopt;
        std::optional<Number> serviceFee = std::nullopt;
        std::optional<Number> lateFee = std::nullopt;
        std::optional<Number> closeFee = std::nullopt;
        std::optional<TenthBips32> overFee = std::nullopt;
        std::optional<TenthBips32> interest = std::nullopt;
        std::optional<TenthBips32> lateInterest = std::nullopt;
        std::optional<TenthBips32> closeInterest = std::nullopt;
        std::optional<TenthBips32> overpaymentInterest = std::nullopt;
        std::optional<std::uint32_t> payTotal = std::nullopt;
        std::optional<std::uint32_t> payInterval = std::nullopt;
        std::optional<std::uint32_t> gracePd = std::nullopt;
        std::optional<std::uint32_t> flags = std::nullopt;
        // NOLINTEND(readability-redundant-member-init)
 
        template <class... FN>
        jtx::JTx
        operator()(jtx::Env& env, BrokerInfo const& broker, FN const&... fN) const
        {
            using namespace jtx;
            using namespace jtx::loan;
 
            JTx jt{loan::set(
                account,
                broker.brokerID,
                broker.asset(principalRequest).number(),
                flags.value_or(0))};
 
            Sig(sfCounterpartySignature, counter)(env, jt);
 
            Fee{setFee.value_or(env.current()->fees().base * 2)}(env, jt);
 
            if (counterpartyExplicit)
                kCounterparty(counter)(env, jt);
            if (originationFee)
                kLoanOriginationFee(broker.asset(*originationFee).number())(env, jt);
            if (serviceFee)
                kLoanServiceFee(broker.asset(*serviceFee).number())(env, jt);
            if (lateFee)
                kLatePaymentFee(broker.asset(*lateFee).number())(env, jt);
            if (closeFee)
                kClosePaymentFee(broker.asset(*closeFee).number())(env, jt);
            if (overFee)
                kOverpaymentFee (*overFee)(env, jt);
            if (interest)
                kInterestRate (*interest)(env, jt);
            if (lateInterest)
                kLateInterestRate (*lateInterest)(env, jt);
            if (closeInterest)
                kCloseInterestRate (*closeInterest)(env, jt);
            if (overpaymentInterest)
                kOverpaymentInterestRate (*overpaymentInterest)(env, jt);
            if (payTotal)
                kPaymentTotal (*payTotal)(env, jt);
            if (payInterval)
                kPaymentInterval (*payInterval)(env, jt);
            if (gracePd)
                kGracePeriod (*gracePd)(env, jt);
 
            return env.jt(jt, fN...);
        }
    };
 
    struct PaymentParameters
    {
        Number overpaymentFactor = Number{1};
        std::optional<Number> overpaymentExtra = std::nullopt;
        std::uint32_t flags = 0;
        bool showStepBalances = false;
        bool validateBalances = true;
 
        static PaymentParameters const&
        defaults()
        {
            static PaymentParameters const kResult{};
            return kResult;
        }
    };
 
    struct LoanState
    {
        std::uint32_t previousPaymentDate = 0;
        NetClock::time_point startDate;
        std::uint32_t nextPaymentDate = 0;
        std::uint32_t paymentRemaining = 0;
        std::int32_t const loanScale = 0;
        Number totalValue = 0;
        Number principalOutstanding = 0;
        Number managementFeeOutstanding = 0;
        Number periodicPayment = 0;
        std::uint32_t flags = 0;
        std::uint32_t const paymentInterval = 0;
        TenthBips32 const interestRate{};
    };

    struct VerifyLoanStatus
    {
    public:
        jtx::Env const& env;
        BrokerInfo const& broker;
        jtx::Account const& pseudoAccount;
        Keylet const& loanKeylet;
 
        VerifyLoanStatus(
            jtx::Env const& env,
            BrokerInfo const& broker,
            jtx::Account const& pseudo,
            Keylet const& keylet)
            : env(env), broker(broker), pseudoAccount(pseudo), loanKeylet(keylet)
        {
        }

        void
        checkBroker(
            Number const& principalOutstanding,
            Number const& interestOwed,
            TenthBips32 interestRate,
            std::uint32_t paymentInterval,
            std::uint32_t paymentsRemaining,
            std::uint32_t ownerCount) const
        {
            using namespace jtx;
            if (auto brokerSle = env.le(keylet::loanBroker(broker.brokerID));
                env.test.BEAST_EXPECT(brokerSle))
            {
                TenthBips16 const managementFeeRate{brokerSle->at(sfManagementFeeRate)};
                auto const brokerDebt = brokerSle->at(sfDebtTotal);
 
                if (auto vaultSle = env.le(keylet::vault(brokerSle->at(sfVaultID)));
                    env.test.BEAST_EXPECT(vaultSle))
                {
                    auto const expectedDebt =
                        env.current()->rules().enabled(featureLendingProtocolV1_1) &&
                            getVaultVersion(vaultSle) == VaultVersion::CashBasis
                        ? principalOutstanding
                        : principalOutstanding + interestOwed;
                    env.test.BEAST_EXPECT(brokerDebt == expectedDebt);
                    env.test.BEAST_EXPECT(
                        env.balance(pseudoAccount, broker.asset).number() ==
                        brokerSle->at(sfCoverAvailable));
                    env.test.BEAST_EXPECT(brokerSle->at(sfOwnerCount) == ownerCount);
 
                    Account const vaultPseudo{"vaultPseudoAccount", vaultSle->at(sfAccount)};
                    env.test.BEAST_EXPECT(
                        vaultSle->at(sfAssetsAvailable) ==
                        env.balance(vaultPseudo, broker.asset).number());
                    if (ownerCount == 0)
                    {
                        // The Vault must be perfectly balanced if there
                        // are no loans outstanding
                        auto const total = vaultSle->at(sfAssetsTotal);
                        auto const available = vaultSle->at(sfAssetsAvailable);
                        env.test.BEAST_EXPECT(total == available);
                        env.test.BEAST_EXPECT(vaultSle->at(sfLossUnrealized) == 0);
                    }
                }
            }
        }
 
        void
        checkPayment(
            std::int32_t loanScale,
            jtx::Account const& account,
            jtx::PrettyAmount const& balanceBefore,
            STAmount const& expectedPayment,
            jtx::PrettyAmount const& adjustment) const
        {
            auto const borrowerScale = std::max(loanScale, balanceBefore.number().exponent());
 
            STAmount const balanceChangeAmount{
                broker.asset,
                roundToAsset(broker.asset, expectedPayment + adjustment, borrowerScale)};
            {
                auto const difference = roundToScale(
                    env.balance(account, broker.asset) - (balanceBefore - balanceChangeAmount),
                    borrowerScale);
                env.test.expect(
                    roundToScale(difference, loanScale) >= beast::kZero,
                    "Balance before: " + to_string(balanceBefore.value()) +
                        ", expected change: " + to_string(balanceChangeAmount) +
                        ", difference (balance after - expected): " + to_string(difference),
                    __FILE__,
                    __LINE__);
            }
        }

        void
        operator()(
            std::uint32_t previousPaymentDate,
            std::uint32_t nextPaymentDate,
            std::uint32_t paymentRemaining,
            Number const& loanScale,
            Number const& totalValue,
            Number const& principalOutstanding,
            Number const& managementFeeOutstanding,
            Number const& periodicPayment,
            std::uint32_t flags) const
        {
            using namespace jtx;
            if (auto loan = env.le(loanKeylet); env.test.BEAST_EXPECT(loan))
            {
                env.test.BEAST_EXPECT(loan->at(sfPreviousPaymentDueDate) == previousPaymentDate);
                env.test.BEAST_EXPECT(loan->at(sfPaymentRemaining) == paymentRemaining);
                env.test.BEAST_EXPECT(loan->at(sfNextPaymentDueDate) == nextPaymentDate);
                env.test.BEAST_EXPECT(loan->at(sfLoanScale) == loanScale);
                env.test.BEAST_EXPECT(loan->at(sfTotalValueOutstanding) == totalValue);
                env.test.BEAST_EXPECT(loan->at(sfPrincipalOutstanding) == principalOutstanding);
                env.test.BEAST_EXPECT(
                    loan->at(sfManagementFeeOutstanding) == managementFeeOutstanding);
                env.test.BEAST_EXPECT(loan->at(sfPeriodicPayment) == periodicPayment);
                env.test.BEAST_EXPECT(loan->at(sfFlags) == flags);
 
                auto const ls = constructLoanState(loan);
 
                auto const interestRate = TenthBips32{loan->at(sfInterestRate)};
                auto const paymentInterval = loan->at(sfPaymentInterval);
                checkBroker(
                    principalOutstanding,
                    ls.interestDue,
                    interestRate,
                    paymentInterval,
                    paymentRemaining,
                    1);
 
                if (auto brokerSle = env.le(keylet::loanBroker(broker.brokerID));
                    env.test.BEAST_EXPECT(brokerSle))
                {
                    if (auto vaultSle = env.le(keylet::vault(brokerSle->at(sfVaultID)));
                        env.test.BEAST_EXPECT(vaultSle))
                    {
                        if (((flags & lsfLoanImpaired) != 0u) && ((flags & lsfLoanDefault) == 0u))
                        {
                            env.test.BEAST_EXPECT(
                                vaultSle->at(sfLossUnrealized) ==
                                (env.current()->rules().enabled(featureLendingProtocolV1_1) &&
                                         getVaultVersion(vaultSle) == VaultVersion::CashBasis
                                     ? principalOutstanding
                                     : totalValue - managementFeeOutstanding));
                        }
                        else
                        {
                            env.test.BEAST_EXPECT(vaultSle->at(sfLossUnrealized) == 0);
                        }
                    }
                }
            }
        }

        void
        operator()(LoanState const& state) const
        {
            operator()(
                state.previousPaymentDate,
                state.nextPaymentDate,
                state.paymentRemaining,
                state.loanScale,
                state.totalValue,
                state.principalOutstanding,
                state.managementFeeOutstanding,
                state.periodicPayment,
                state.flags);
        };
    };
 
    BrokerInfo
    createVaultAndBroker(
        jtx::Env& env,
        jtx::PrettyAsset const& asset,
        jtx::Account const& lender,
        BrokerParameters const& params = BrokerParameters::defaults())
    {
        using namespace jtx;
 
        Vault const vault{env};
 
        auto const deposit = asset(params.vaultDeposit);
        auto const debtMaximumValue = asset(params.debtMax).value();
        auto const coverDepositValue = asset(params.coverDeposit).value();
 
        auto const coverRateMinValue = params.coverRateMin;
 
        std::optional<std::uint32_t> subscriptionDate;
        std::optional<std::uint32_t> redemptionDate;
        if (params.vaultKind == VaultKind::ClosedEnded)
        {
            auto const nowSec = env.now().time_since_epoch().count();
            subscriptionDate = nowSec + params.subscriptionOffset;
            redemptionDate = *subscriptionDate + params.redemptionOffset;
        }
 
        auto [tx, vaultKeylet] = vault.create(
            {.owner = lender,
             .asset = asset,
             .vaultKind = params.vaultKind == VaultKind::OpenEnded
                 ? std::optional<std::uint8_t>{}
                 : std::optional<std::uint8_t>{std::to_underlying(params.vaultKind)},
             .subscriptionDate = subscriptionDate,
             .redemptionDate = redemptionDate});
        if (params.vaultScale)
            tx[sfScale] = *params.vaultScale;
        env(tx);
        env.close();
        BEAST_EXPECT(env.le(vaultKeylet));
 
        env(vault.deposit({.depositor = lender, .id = vaultKeylet.key, .amount = deposit}));
        env.close();
        if (auto const vault = env.le(keylet::vault(vaultKeylet.key)); BEAST_EXPECT(vault))
        {
            BEAST_EXPECT(vault->at(sfAssetsAvailable) == deposit.value());
        }
 
        // For closed-ended vaults, advance past SubscriptionDate so subsequent LoanSet operations
        // run in the Investment phase (unless the caller explicitly asked to stay in Subscription).
        if (subscriptionDate && !params.skipPhaseAdvance)
        {
            using d = NetClock::duration;
            using tp = NetClock::time_point;
            env.close(tp{d{*subscriptionDate + 1}});
        }
 
        auto const keylet = keylet::loanBroker(lender.id(), SeqProxy::rawSequence(env.seq(lender)));
 
        using namespace loan_broker;
        env(set(lender, vaultKeylet.key, params.flags),
            kData(params.data),
            kManagementFeeRate(params.managementFeeRate),
            kDebtMaximum(debtMaximumValue),
            kCoverRateMinimum(coverRateMinValue),
            kCoverRateLiquidation(TenthBips32(params.coverRateLiquidation)));
 
        if (coverDepositValue != beast::kZero)
            env(coverDeposit(lender, keylet.key, coverDepositValue));
 
        env.close();
 
        return {asset, keylet, vaultKeylet, params, subscriptionDate, redemptionDate};
    }

    LoanState
    getCurrentState(jtx::Env const& env, BrokerInfo const& broker, Keylet const& loanKeylet)
    {
        using d = NetClock::duration;
        using tp = NetClock::time_point;
 
        // Lookup the current loan state
        if (auto loan = env.le(loanKeylet); BEAST_EXPECT(loan))
        {
            return LoanState{
                .previousPaymentDate = loan->at(sfPreviousPaymentDueDate),
                .startDate = tp{d{loan->at(sfStartDate)}},
                .nextPaymentDate = loan->at(sfNextPaymentDueDate),
                .paymentRemaining = loan->at(sfPaymentRemaining),
                .loanScale = loan->at(sfLoanScale),
                .totalValue = loan->at(sfTotalValueOutstanding),
                .principalOutstanding = loan->at(sfPrincipalOutstanding),
                .managementFeeOutstanding = loan->at(sfManagementFeeOutstanding),
                .periodicPayment = loan->at(sfPeriodicPayment),
                .flags = loan->at(sfFlags),
                .paymentInterval = loan->at(sfPaymentInterval),
                .interestRate = TenthBips32{loan->at(sfInterestRate)},
            };
        }
        return LoanState{};
    }

    LoanState
    getCurrentState(
        jtx::Env const& env,
        BrokerInfo const& broker,
        Keylet const& loanKeylet,
        VerifyLoanStatus const& verifyLoanStatus)
    {
        using namespace std::chrono_literals;
        using d = NetClock::duration;
        using tp = NetClock::time_point;
 
        auto const state = getCurrentState(env, broker, loanKeylet);
        BEAST_EXPECT(state.previousPaymentDate == 0);
        BEAST_EXPECT(tp{d{state.nextPaymentDate}} == state.startDate + 600s);
        BEAST_EXPECT(state.paymentRemaining == 12);
        BEAST_EXPECT(state.principalOutstanding == broker.asset(1000).value());
        BEAST_EXPECT(
            state.loanScale >=
            (broker.asset.integral()
                 ? 0
                 : std::max(broker.vaultScale(env), state.principalOutstanding.exponent())));
        BEAST_EXPECT(state.paymentInterval == 600);
        {
            NumberRoundModeGuard const mg(Number::RoundingMode::Upward);
            BEAST_EXPECT(
                state.totalValue ==
                roundToAsset(
                    broker.asset, state.periodicPayment * state.paymentRemaining, state.loanScale));
        }
        BEAST_EXPECT(
            state.managementFeeOutstanding ==
            computeManagementFee(
                broker.asset,
                state.totalValue - state.principalOutstanding,
                broker.params.managementFeeRate,
                state.loanScale));
 
        verifyLoanStatus(state);
 
        return state;
    }
 
    bool
    canImpairLoan(jtx::Env const& env, BrokerInfo const& broker, LoanState const& state)
    {
        if (auto const brokerSle = env.le(keylet::loanBroker(broker.brokerID));
            BEAST_EXPECT(brokerSle))
        {
            if (auto const vaultSle = env.le(keylet::vault(brokerSle->at(sfVaultID)));
                BEAST_EXPECT(vaultSle))
            {
                // log << vaultSle->getJson() << std::endl;
                auto const assetsUnavailable =
                    vaultSle->at(sfAssetsTotal) - vaultSle->at(sfAssetsAvailable);
                auto const unrealizedLoss = vaultSle->at(sfLossUnrealized) +
                    (env.current()->rules().enabled(featureLendingProtocolV1_1) &&
                             getVaultVersion(vaultSle) == VaultVersion::CashBasis
                         ? state.principalOutstanding
                         : state.totalValue - state.managementFeeOutstanding);
 
                if (!BEAST_EXPECT(unrealizedLoss <= assetsUnavailable))
                {
                    return false;
                }
            }
        }
        return true;
    }
 
    enum class AssetType { XRP = 0, IOU = 1, MPT = 2 };
 
    // Specify the accounts as params to allow other accounts to be used
    jtx::PrettyAsset
    createAsset(
        jtx::Env& env,
        AssetType assetType,
        BrokerParameters const& brokerParams,
        jtx::Account const& issuer,
        jtx::Account const& lender,
        jtx::Account const& borrower)
    {
        using namespace jtx;
 
        switch (assetType)
        {
            case AssetType::XRP:
                // TODO: remove the factor, and set up loans in drops
                return PrettyAsset{xrpIssue(), 1'000'000};
 
            case AssetType::IOU: {
                PrettyAsset const asset{issuer[iouCurrency_]};
 
                auto const limit =
                    asset(100 * (brokerParams.vaultDeposit + brokerParams.coverDeposit));
                if (lender != issuer)
                    env(trust(lender, limit));
                if (borrower != issuer)
                    env(trust(borrower, limit));
 
                return asset;
            }
 
            case AssetType::MPT: {
                // Enough to cover initial fees
                if (!env.le(keylet::account(issuer)))
                    env.fund(env.current()->fees().accountReserve(10, 1) * 10, issuer);
                if (!env.le(keylet::account(lender)))
                    env.fund(env.current()->fees().accountReserve(10, 1) * 10, noripple(lender));
                if (!env.le(keylet::account(borrower)))
                    env.fund(env.current()->fees().accountReserve(10, 1) * 10, noripple(borrower));
 
                MPTTester mptt{env, issuer, kMptInitNoFund};
                mptt.create({.flags = tfMPTCanClawback | tfMPTCanTransfer | tfMPTCanLock});
                // Scale the MPT asset so interest is interesting
                PrettyAsset const asset{mptt.issuanceID(), 10'000};
                // Need to do the authorization here because mptt isn't
                // accessible outside
                if (lender != issuer)
                    mptt.authorize({.account = lender});
                if (borrower != issuer)
                    mptt.authorize({.account = borrower});
 
                env.close();
 
                return asset;
            }
 
            default:
                throw std::runtime_error("Unknown asset type");
        }
    }
 
    // Predicts the keylet of the next loan `broker` will originate, before
    // that loan exists, by reading the broker's current LoanSequence.
    Keylet
    nextLoanKeylet(jtx::Env const& env, BrokerInfo const& broker)
    {
        auto const brokerStateBefore = env.le(keylet::loanBroker(broker.brokerID));
        if (!BEAST_EXPECT(brokerStateBefore))
            return keylet::loan(broker.brokerID, SeqProxy::rawSequence(0));
        auto const loanSequence = brokerStateBefore->at(sfLoanSequence);
        return keylet::loan(broker.brokerID, SeqProxy::rawSequence(loanSequence));
    }
 
    // Funds issuer/lender/borrower with XRP, creates an IOU asset issued by
    // `issuer`, establishes trustlines for lender and borrower, and pays
    // them starting balances. This is the exact setup shared by several of
    // the fuzzer-derived regression tests below.
    jtx::PrettyAsset
    createFundedIouAsset(
        jtx::Env& env,
        jtx::Account const& issuer,
        jtx::Account const& lender,
        jtx::Account const& borrower,
        Number const& lenderPay = 100'000'000,
        Number const& borrowerPay = 1'000'000)
    {
        using namespace jtx;
 
        env.fund(XRP(1'000'000), issuer, lender, borrower);
        env.close();
 
        PrettyAsset const iouAsset = issuer[iouCurrency_];
        auto trustLenderTx = env.json(trust(lender, iouAsset(1'000'000'000)));
        env(trustLenderTx);
        auto trustBorrowerTx = env.json(trust(borrower, iouAsset(1'000'000'000)));
        env(trustBorrowerTx);
        auto payLenderTx = pay(issuer, lender, iouAsset(lenderPay));
        env(payLenderTx);
        auto payIssuerTx = pay(issuer, borrower, iouAsset(borrowerPay));
        env(payIssuerTx);
        env.close();
 
        return iouAsset;
    }
 
    // Funds issuer/lender/borrower with XRP, sets DefaultRipple on the
    // issuer, creates a "USD" IOU asset with a large trust limit, and pays
    // lender/borrower starting balances. Shared setup for several
    // overpayment/rounding regression tests below.
    static jtx::PrettyAsset
    createFundedRippleIouAsset(
        jtx::Env& env,
        jtx::Account const& issuer,
        jtx::Account const& lender,
        jtx::Account const& borrower,
        Number const& lenderPay = 1'000'000,
        Number const& borrowerPay = 1'000'000)
    {
        using namespace jtx;
 
        env.fund(XRP(1'000'000), issuer, lender, borrower);
        env(fset(issuer, asfDefaultRipple));
        env.close();
 
        PrettyAsset const iouAsset = issuer["USD"];
        STAmount const iouLimit{iouAsset.raw(), Number{9'999'999'999'999'999LL}};
        env(trust(lender, iouLimit));
        env(trust(borrower, iouLimit));
        env(pay(issuer, lender, iouAsset(lenderPay)));
        env(pay(issuer, borrower, iouAsset(borrowerPay)));
        env.close();
 
        return iouAsset;
    }
 
    // Returns the broker's pseudo-account, or `fallback` if the broker's
    // ledger entry cannot be read.
    jtx::Account
    brokerPseudoAccount(jtx::Env const& env, BrokerInfo const& broker, jtx::Account const& fallback)
    {
        auto const brokerSle = env.le(keylet::loanBroker(broker.brokerID));
        if (!BEAST_EXPECT(brokerSle))
            return fallback;
        auto const brokerPseudo = brokerSle->at(sfAccount);
        return jtx::Account("Broker pseudo-account", brokerPseudo);
    }
 
    void
    describeLoan(
        jtx::Env& env,
        BrokerParameters const& brokerParams,
        LoanParameters const& loanParams,
        AssetType assetType,
        jtx::Account const& issuer,
        jtx::Account const& lender,
        jtx::Account const& borrower)
    {
        using namespace jtx;
 
        auto const asset = createAsset(env, assetType, brokerParams, issuer, lender, borrower);
        auto const principal = asset(loanParams.principalRequest).number();
        auto const interest = loanParams.interest.value_or(TenthBips32{});
        auto const interval = loanParams.payInterval.value_or(LoanSet::kDefaultPaymentInterval);
        auto const total = loanParams.payTotal.value_or(LoanSet::kDefaultPaymentTotal);
        auto const feeRate = brokerParams.managementFeeRate;
        auto const props = computeLoanProperties(
            env.current()->rules(),
            asset,
            principal,
            interest,
            interval,
            total,
            feeRate,
            asset(brokerParams.vaultDeposit).number().exponent());
        log << "Loan properties:\n"
            << "\tPrincipal: " << principal << std::endl
            << "\tInterest rate: " << interest << std::endl
            << "\tPayment interval: " << interval << std::endl
            << "\tManagement Fee Rate: " << feeRate << std::endl
            << "\tTotal Payments: " << total << std::endl
            << "\tPeriodic Payment: " << props.periodicPayment << std::endl
            << "\tTotal Value: " << props.loanState.valueOutstanding << std::endl
            << "\tManagement Fee: " << props.loanState.managementFeeDue << std::endl
            << "\tLoan Scale: " << props.loanScale << std::endl
            << "\tFirst payment principal: " << props.firstPaymentPrincipal << std::endl;
 
        // checkGuards returns a TER, so success is 0
        BEAST_EXPECT(!checkLoanGuards(
            asset,
            asset(loanParams.principalRequest).number(),
            loanParams.interest.value_or(TenthBips32{}) != beast::kZero,
            loanParams.payTotal.value_or(LoanSet::kDefaultPaymentTotal),
            props,
            env.journal));
    }
 
    std::optional<std::tuple<BrokerInfo, Keylet, jtx::Account>>
    createLoan(
        jtx::Env& env,
        AssetType assetType,
        BrokerParameters const& brokerParams,
        LoanParameters const& loanParams,
        jtx::Account const& issuer,
        jtx::Account const& lender,
        jtx::Account const& borrower)
    {
        using namespace jtx;
 
        // Enough to cover initial fees
        env.fund(env.current()->fees().accountReserve(10, 1) * 10, issuer);
        if (lender != issuer)
            env.fund(env.current()->fees().accountReserve(10, 1) * 10, noripple(lender));
        if (borrower != issuer && borrower != lender)
            env.fund(env.current()->fees().accountReserve(10, 1) * 10, noripple(borrower));
 
        describeLoan(env, brokerParams, loanParams, assetType, issuer, lender, borrower);
 
        // Make the asset
        auto const asset = createAsset(env, assetType, brokerParams, issuer, lender, borrower);
 
        env.close();
        if (asset.native() || lender != issuer)
        {
            env(
                pay((asset.native() ? env.master : issuer),
                    lender,
                    asset(brokerParams.vaultDeposit + brokerParams.coverDeposit)));
        }
        // Fund the borrower later once we know the total loan
        // size
 
        BrokerInfo const broker = createVaultAndBroker(env, asset, lender, brokerParams);
 
        auto const pseudoAcctOpt = [&]() -> std::optional<Account> {
            auto const brokerSle = env.le(keylet::loanBroker(broker.brokerID));
            if (!BEAST_EXPECT(brokerSle))
                return std::nullopt;
            auto const brokerPseudo = brokerSle->at(sfAccount);
            return Account("Broker pseudo-account", brokerPseudo);
        }();
        if (!pseudoAcctOpt)
            return std::nullopt;
        Account const& pseudoAcct = *pseudoAcctOpt;
 
        auto const loanKeyletOpt = [&]() -> std::optional<Keylet> {
            auto const brokerSle = env.le(keylet::loanBroker(broker.brokerID));
            if (!BEAST_EXPECT(brokerSle))
                return std::nullopt;
 
            // Broker has no loans
            BEAST_EXPECT(brokerSle->at(sfOwnerCount) == 0);
 
            // The loan keylet is based on the LoanSequence of the
            // _LOAN_BROKER_ object.
            auto const loanSequence = brokerSle->at(sfLoanSequence);
            return keylet::loan(broker.brokerID, SeqProxy::rawSequence(loanSequence));
        }();
        if (!loanKeyletOpt)
            return std::nullopt;
        Keylet const& loanKeylet = *loanKeyletOpt;
 
        env(loanParams(env, broker));
 
        env.close();
 
        return std::make_tuple(broker, loanKeylet, pseudoAcct);
    }
 
    static void
    topUpBorrower(
        jtx::Env& env,
        BrokerInfo const& broker,
        jtx::Account const& issuer,
        jtx::Account const& borrower,
        LoanState const& state,
        std::optional<Number> const& servFee)
    {
        using namespace jtx;
 
        STAmount const serviceFee = broker.asset(servFee.value_or(0));
 
        // Ensure the borrower has enough funds to make the payments
        // (including tx fees, if necessary)
        auto const borrowerBalance = env.balance(borrower, broker.asset);
 
        auto const baseFee = env.current()->fees().base;
 
        // Add extra for transaction fees and reserves, if appropriate, or a
        // tiny amount for the extra paid in each transaction
        auto const totalNeeded = state.totalValue + (serviceFee * state.paymentRemaining) +
            (broker.asset.native() ? Number(
                                         baseFee * state.paymentRemaining +
                                         accountReserve(*env.current(), borrower.id(), env.journal))
                                   : broker.asset(15).number());
 
        auto const shortage = totalNeeded - borrowerBalance.number();
 
        if (shortage > beast::kZero && (broker.asset.native() || issuer != borrower))
        {
            env(
                pay((broker.asset.native() ? env.master : issuer),
                    borrower,
                    STAmount{broker.asset, shortage}));
        }
    }
 
    void
    makeLoanPayments(
        jtx::Env& env,
        BrokerInfo const& broker,
        LoanParameters const& loanParams,
        Keylet const& loanKeylet,
        VerifyLoanStatus const& verifyLoanStatus,
        jtx::Account const& issuer,
        jtx::Account const& lender,
        jtx::Account const& borrower,
        PaymentParameters const& paymentParams = PaymentParameters::defaults())
    {
        // Make all the individual payments
        using namespace jtx;
        using namespace jtx::loan;
        using namespace std::chrono_literals;
        using d = NetClock::duration;
 
        bool const showStepBalances = paymentParams.showStepBalances;
 
        auto const currencyLabel = getCurrencyLabel(broker.asset);
 
        auto const baseFee = env.current()->fees().base;
 
        env.close();
        auto state = getCurrentState(env, broker, loanKeylet);
 
        verifyLoanStatus(state);
 
        STAmount const serviceFee = broker.asset(loanParams.serviceFee.value_or(0));
 
        topUpBorrower(env, broker, issuer, borrower, state, loanParams.serviceFee);
 
        // Periodic payment amount will consist of
        // 1. principal outstanding (1000)
        // 2. interest interest rate (at 12%)
        // 3. payment interval (600s)
        // 4. loan service fee (2)
        // Calculate these values without the helper functions
        // to verify they're working correctly The numbers in
        // the below BEAST_EXPECTs may not hold across assets.
        auto const periodicRate = loanPeriodicRate(state.interestRate, state.paymentInterval);
        STAmount const roundedPeriodicPayment{
            broker.asset,
            roundPeriodicPayment(broker.asset, state.periodicPayment, state.loanScale)};
 
        if (!showStepBalances)
        {
            log << currencyLabel << " Payment components: "
                << "Payments remaining, "
                << "rawInterest, rawPrincipal, "
                   "rawMFee, "
                << "trackedValueDelta, trackedPrincipalDelta, "
                   "trackedInterestDelta, trackedMgmtFeeDelta, special"
                << std::endl;
        }
 
        // Include the service fee
        STAmount const totalDue = roundToScale(
            roundedPeriodicPayment + serviceFee, state.loanScale, Number::RoundingMode::Upward);
 
        auto currentRoundedState = constructLoanState(
            state.totalValue, state.principalOutstanding, state.managementFeeOutstanding);
        {
            auto const raw = computeTheoreticalLoanState(
                env.current()->rules(),
                state.periodicPayment,
                periodicRate,
                state.paymentRemaining,
                broker.params.managementFeeRate);
 
            if (showStepBalances)
            {
                log << currencyLabel << " Starting loan balances: "
                    << "\n\tTotal value: " << currentRoundedState.valueOutstanding
                    << "\n\tPrincipal: " << currentRoundedState.principalOutstanding
                    << "\n\tInterest: " << currentRoundedState.interestDue
                    << "\n\tMgmt fee: " << currentRoundedState.managementFeeDue
                    << "\n\tPayments remaining " << state.paymentRemaining << std::endl;
            }
            else
            {
                log << currencyLabel << " Loan starting state: " << state.paymentRemaining << ", "
                    << raw.interestDue << ", " << raw.principalOutstanding << ", "
                    << raw.managementFeeDue << ", " << currentRoundedState.valueOutstanding << ", "
                    << currentRoundedState.principalOutstanding << ", "
                    << currentRoundedState.interestDue << ", "
                    << currentRoundedState.managementFeeDue << std::endl;
            }
        }
 
        // Try to pay a little extra to show that it's _not_
        // taken
        auto const extraAmount = paymentParams.overpaymentExtra
            ? broker.asset(*paymentParams.overpaymentExtra).value()
            : std::min(broker.asset(10).value(), STAmount{broker.asset, totalDue / 20});
 
        STAmount const transactionAmount =
            STAmount{broker.asset, totalDue * paymentParams.overpaymentFactor} + extraAmount;
 
        auto const borrowerInitialBalance = env.balance(borrower, broker.asset).number();
        auto const initialState = state;
        xrpl::detail::PaymentComponents totalPaid{
            .trackedValueDelta = 0, .trackedPrincipalDelta = 0, .trackedManagementFeeDelta = 0};
        Number totalInterestPaid = 0;
        Number totalFeesPaid = 0;
        std::size_t totalPaymentsMade = 0;
 
        xrpl::LoanState currentTrueState = computeTheoreticalLoanState(
            env.current()->rules(),
            state.periodicPayment,
            periodicRate,
            state.paymentRemaining,
            broker.params.managementFeeRate);
 
        auto validateBorrowerBalance = [&]() {
            if (borrower == issuer || !paymentParams.validateBalances)
                return;
            auto const totalSpent =
                (totalPaid.trackedValueDelta + totalFeesPaid +
                 (broker.asset.native() ? Number(baseFee) * totalPaymentsMade : kNumZero));
            BEAST_EXPECT(
                env.balance(borrower, broker.asset).number() ==
                borrowerInitialBalance - totalSpent);
        };
 
        auto const defaultRound = broker.asset.integral() ? 3 : 0;
        auto truncate = [defaultRound](Number const& n, std::optional<int> places = std::nullopt) {
            auto const p = places.value_or(defaultRound);
            if (p == 0)
                return n;
            auto const factor = Number{1, p};
            return (n * factor).truncate() / factor;
        };
        while (state.paymentRemaining > 0)
        {
            validateBorrowerBalance();
            // Compute the expected principal amount
            auto const paymentComponents = xrpl::detail::computePaymentComponents(
                env.current()->rules(),
                broker.asset.raw(),
                state.loanScale,
                state.totalValue,
                state.principalOutstanding,
                state.managementFeeOutstanding,
                state.periodicPayment,
                periodicRate,
                state.paymentRemaining,
                broker.params.managementFeeRate);
 
            BEAST_EXPECT(
                paymentComponents.trackedValueDelta <= roundedPeriodicPayment ||
                (paymentComponents.specialCase == xrpl::detail::PaymentSpecialCase::Final &&
                 paymentComponents.trackedValueDelta >= roundedPeriodicPayment));
            BEAST_EXPECT(
                paymentComponents.trackedValueDelta ==
                paymentComponents.trackedPrincipalDelta + paymentComponents.trackedInterestPart() +
                    paymentComponents.trackedManagementFeeDelta);
 
            xrpl::LoanState const nextTrueState = computeTheoreticalLoanState(
                env.current()->rules(),
                state.periodicPayment,
                periodicRate,
                state.paymentRemaining - 1,
                broker.params.managementFeeRate);
            xrpl::detail::LoanStateDeltas const deltas = currentTrueState - nextTrueState;
            BEAST_EXPECT(
                deltas.total() == deltas.principal + deltas.interest + deltas.managementFee);
            BEAST_EXPECT(
                paymentComponents.specialCase == xrpl::detail::PaymentSpecialCase::Final ||
                deltas.total() == state.periodicPayment ||
                (state.loanScale - (deltas.total() - state.periodicPayment).exponent()) > 14);
 
            if (!showStepBalances)
            {
                log << currencyLabel << " Payment components: " << state.paymentRemaining << ", "
 
                    << deltas.interest << ", " << deltas.principal << ", " << deltas.managementFee
                    << ", " << paymentComponents.trackedValueDelta << ", "
                    << paymentComponents.trackedPrincipalDelta << ", "
                    << paymentComponents.trackedInterestPart() << ", "
                    << paymentComponents.trackedManagementFeeDelta << ", " << [&]() -> char const* {
                    if (paymentComponents.specialCase == ::xrpl::detail::PaymentSpecialCase::Final)
                        return "final";
                    if (paymentComponents.specialCase == ::xrpl::detail::PaymentSpecialCase::Extra)
                        return "extra";
                    return "none";
                }() << std::endl;
            }
 
            auto const totalDueAmount =
                STAmount{broker.asset, paymentComponents.trackedValueDelta + serviceFee};
 
            if (paymentParams.validateBalances)
            {
                // Due to the rounding algorithms to keep the interest and
                // principal in sync with "true" values, the computed amount
                // may be a little less than the rounded fixed payment
                // amount. For integral types, the difference should be < 3
                // (1 unit for each of the interest and management fee). For
                // IOUs, the difference should be dust.
                Number const diff = totalDue - totalDueAmount;
                BEAST_EXPECT(
                    paymentComponents.specialCase == xrpl::detail::PaymentSpecialCase::Final ||
                    diff == beast::kZero ||
                    (diff > beast::kZero &&
                     ((broker.asset.integral() && (static_cast<Number>(diff) < 3)) ||
                      (state.loanScale - diff.exponent() > 13))));
 
                BEAST_EXPECT(
                    paymentComponents.trackedPrincipalDelta >= beast::kZero &&
                    paymentComponents.trackedPrincipalDelta <= state.principalOutstanding);
                BEAST_EXPECT(
                    paymentComponents.specialCase != xrpl::detail::PaymentSpecialCase::Final ||
                    paymentComponents.trackedPrincipalDelta == state.principalOutstanding);
            }
 
            auto const borrowerBalanceBeforePayment = env.balance(borrower, broker.asset);
 
            // Make the payment
            env(pay(borrower, loanKeylet.key, transactionAmount, paymentParams.flags));
 
            env.close(d{state.paymentInterval / 2});
 
            if (paymentParams.validateBalances)
            {
                // Need to account for fees if the loan is in XRP
                PrettyAmount adjustment = broker.asset(0);
                if (broker.asset.native())
                {
                    adjustment = env.current()->fees().base;
                }
 
                // Check the result
                verifyLoanStatus.checkPayment(
                    state.loanScale,
                    borrower,
                    borrowerBalanceBeforePayment,
                    totalDueAmount,
                    adjustment);
            }
 
            if (showStepBalances)
            {
                auto const loanSle = env.le(loanKeylet);
                if (!BEAST_EXPECT(loanSle))
                {
                    // No reason for this not to exist
                    return;
                }
                auto const current = constructLoanState(loanSle);
                auto const errors = nextTrueState - current;
                log << currencyLabel << " Loan balances: "
                    << "\n\tAmount taken: " << paymentComponents.trackedValueDelta
                    << "\n\tTotal value: " << current.valueOutstanding
                    << " (true: " << truncate(nextTrueState.valueOutstanding)
                    << ", error: " << truncate(errors.total())
                    << ")\n\tPrincipal: " << current.principalOutstanding
                    << " (true: " << truncate(nextTrueState.principalOutstanding)
                    << ", error: " << truncate(errors.principal)
                    << ")\n\tInterest: " << current.interestDue
                    << " (true: " << truncate(nextTrueState.interestDue)
                    << ", error: " << truncate(errors.interest)
                    << ")\n\tMgmt fee: " << current.managementFeeDue
                    << " (true: " << truncate(nextTrueState.managementFeeDue)
                    << ", error: " << truncate(errors.managementFee) << ")\n\tPayments remaining "
                    << loanSle->at(sfPaymentRemaining) << std::endl;
 
                currentRoundedState = current;
            }
 
            --state.paymentRemaining;
            state.previousPaymentDate = state.nextPaymentDate;
            if (paymentComponents.specialCase == xrpl::detail::PaymentSpecialCase::Final)
            {
                state.paymentRemaining = 0;
                state.nextPaymentDate = 0;
            }
            else
            {
                state.nextPaymentDate += state.paymentInterval;
            }
            state.principalOutstanding -= paymentComponents.trackedPrincipalDelta;
            state.managementFeeOutstanding -= paymentComponents.trackedManagementFeeDelta;
            state.totalValue -= paymentComponents.trackedValueDelta;
 
            if (paymentParams.validateBalances)
                verifyLoanStatus(state);
 
            totalPaid.trackedValueDelta += paymentComponents.trackedValueDelta;
            totalPaid.trackedPrincipalDelta += paymentComponents.trackedPrincipalDelta;
            totalPaid.trackedManagementFeeDelta += paymentComponents.trackedManagementFeeDelta;
            totalInterestPaid += paymentComponents.trackedInterestPart();
            totalFeesPaid += serviceFee;
            ++totalPaymentsMade;
 
            currentTrueState = nextTrueState;
        }
        validateBorrowerBalance();
 
        // Loan is paid off
        BEAST_EXPECT(state.paymentRemaining == 0);
        BEAST_EXPECT(state.principalOutstanding == 0);
 
        auto const initialInterestDue = initialState.totalValue -
            (initialState.principalOutstanding + initialState.managementFeeOutstanding);
        if (paymentParams.validateBalances)
        {
            // Make sure all the payments add up
            BEAST_EXPECT(totalPaid.trackedValueDelta == initialState.totalValue);
            BEAST_EXPECT(totalPaid.trackedPrincipalDelta == initialState.principalOutstanding);
            BEAST_EXPECT(
                totalPaid.trackedManagementFeeDelta == initialState.managementFeeOutstanding);
            // This is almost a tautology given the previous checks, but
            // check it anyway for completeness.
            BEAST_EXPECT(totalInterestPaid == initialInterestDue);
            BEAST_EXPECT(totalPaymentsMade == initialState.paymentRemaining);
        }
 
        if (showStepBalances)
        {
            auto const loanSle = env.le(loanKeylet);
            if (!BEAST_EXPECT(loanSle))
            {
                // No reason for this not to exist
                return;
            }
            log << currencyLabel << " Total amounts paid: "
                << "\n\tTotal value: " << totalPaid.trackedValueDelta
                << " (initial: " << truncate(initialState.totalValue)
                << ", error: " << truncate(initialState.totalValue - totalPaid.trackedValueDelta)
                << ")\n\tPrincipal: " << totalPaid.trackedPrincipalDelta
                << " (initial: " << truncate(initialState.principalOutstanding) << ", error: "
                << truncate(initialState.principalOutstanding - totalPaid.trackedPrincipalDelta)
                << ")\n\tInterest: " << totalInterestPaid
                << " (initial: " << truncate(initialInterestDue)
                << ", error: " << truncate(initialInterestDue - totalInterestPaid)
                << ")\n\tMgmt fee: " << totalPaid.trackedManagementFeeDelta
                << " (initial: " << truncate(initialState.managementFeeOutstanding) << ", error: "
                << truncate(
                       initialState.managementFeeOutstanding - totalPaid.trackedManagementFeeDelta)
                << ")\n\tTotal payments made: " << totalPaymentsMade << std::endl;
        }
    }
 
    void
    runLoan(
        AssetType assetType,
        BrokerParameters const& brokerParams,
        LoanParameters const& loanParams,
        FeatureBitset features)
    {
        using namespace jtx;
 
        Account const issuer("issuer");
        Account const lender("lender");
        Account const borrower("borrower");
 
        Env env(*this, features);
 
        auto loanResult =
            createLoan(env, assetType, brokerParams, loanParams, issuer, lender, borrower);
        if (BEAST_EXPECT(loanResult); !loanResult.has_value())
            return;
 
        auto broker = std::get<BrokerInfo>(*loanResult);
        auto loanKeylet = std::get<Keylet>(*loanResult);
        auto pseudoAcct = std::get<Account>(*loanResult);
 
        VerifyLoanStatus const verifyLoanStatus(env, broker, pseudoAcct, loanKeylet);
 
        makeLoanPayments(
            env,
            broker,
            loanParams,
            loanKeylet,
            verifyLoanStatus,
            issuer,
            lender,
            borrower,
            PaymentParameters{.showStepBalances = true});
    }

    void
    lifecycle(
        std::string const& caseLabel,
        char const* label,
        jtx::Env& env,
        Number const& loanAmount,
        int interestExponent,
        jtx::Account const& lender,
        jtx::Account const& borrower,
        jtx::Account const& evan,
        BrokerInfo const& broker,
        jtx::Account const& pseudoAcct,
        std::uint32_t flags,
        // The end of life callback is expected to take the loan to 0 payments
        // remaining, one way or another
        std::function<void(Keylet const& loanKeylet, VerifyLoanStatus const& verifyLoanStatus)>
            toEndOfLife)
    {
        auto const [keylet, loanSequence] = [&]() {
            auto const brokerSle = env.le(keylet::loanBroker(broker.brokerID));
            if (!BEAST_EXPECT(brokerSle))
            {
                // will be invalid
                return std::make_pair(keylet::loan(broker.brokerID), std::uint32_t(0));
            }
 
            // Broker has no loans
            BEAST_EXPECT(brokerSle->at(sfOwnerCount) == 0);
 
            // The loan keylet is based on the LoanSequence of the _LOAN_BROKER_
            // object.
            auto const loanSequence = brokerSle->at(sfLoanSequence);
            return std::make_pair(
                keylet::loan(broker.brokerID, SeqProxy::rawSequence(loanSequence)), loanSequence);
        }();
 
        VerifyLoanStatus const verifyLoanStatus(env, broker, pseudoAcct, keylet);
 
        // No loans yet
        verifyLoanStatus.checkBroker(0, 0, TenthBips32{0}, 1, 0, 0);
 
        if (!BEAST_EXPECT(loanSequence != 0))
            return;
 
        testcase << caseLabel << " " << label;
 
        using namespace jtx;
        using namespace loan;
        using namespace std::chrono_literals;
 
        auto applyExponent = [interestExponent, this](TenthBips32 value) mutable {
            BEAST_EXPECT(value > TenthBips32(0));
            while (interestExponent > 0)
            {
                auto const oldValue = value;
                value *= 10;
                --interestExponent;
                BEAST_EXPECT(value / 10 == oldValue);
            }
            while (interestExponent < 0)
            {
                auto const oldValue = value;
                value /= 10;
                ++interestExponent;
                BEAST_EXPECT(value * 10 == oldValue);
            }
            return value;
        };
 
        auto const borrowerOwnerCount = env.ownerCount(borrower);
 
        auto const loanSetFee = env.current()->fees().base * 2;
        LoanParameters const loanParams{
            .account = borrower,
            .counter = lender,
            .counterpartyExplicit = false,
            .principalRequest = loanAmount,
            .setFee = loanSetFee,
            .originationFee = 1,
            .serviceFee = 2,
            .lateFee = 3,
            .closeFee = 4,
            .overFee = applyExponent(percentageToTenthBips(5) / 10),
            .interest = applyExponent(percentageToTenthBips(12)),
            // 2.4%
            .lateInterest = applyExponent(percentageToTenthBips(24) / 10),
            .closeInterest = applyExponent(percentageToTenthBips(36) / 10),
            .overpaymentInterest = applyExponent(percentageToTenthBips(48) / 10),
            .payTotal = 12,
            .payInterval = 600,
            .gracePd = 60,
            .flags = flags,
        };
        Number const principalRequestAmount = broker.asset(loanParams.principalRequest).value();
        auto const originationFeeAmount = broker.asset(*loanParams.originationFee).value();
        auto const serviceFeeAmount = broker.asset(*loanParams.serviceFee).value();
        auto const lateFeeAmount = broker.asset(*loanParams.lateFee).value();
        auto const closeFeeAmount = broker.asset(*loanParams.closeFee).value();
 
        auto const borrowerStartbalance = env.balance(borrower, broker.asset);
 
        auto createJtx = loanParams(env, broker);
        // Successfully create a Loan
        env(createJtx);
 
        env.close();
 
        auto const startDate = env.current()->header().parentCloseTime.time_since_epoch().count();
 
        if (auto const brokerSle = env.le(keylet::loanBroker(broker.brokerID));
            BEAST_EXPECT(brokerSle))
        {
            BEAST_EXPECT(brokerSle->at(sfOwnerCount) == 1);
        }
 
        {
            // Need to account for fees if the loan is in XRP
            PrettyAmount adjustment = broker.asset(0);
            if (broker.asset.native())
            {
                adjustment = 2 * env.current()->fees().base;
            }
 
            BEAST_EXPECT(
                env.balance(borrower, broker.asset).value() ==
                borrowerStartbalance.value() + principalRequestAmount - originationFeeAmount -
                    adjustment.value());
        }
 
        auto const loanFlags =
            createJtx.stx->isFlag(tfLoanOverpayment) ? lsfLoanOverpayment : LedgerSpecificFlags(0);
 
        if (auto loan = env.le(keylet); BEAST_EXPECT(loan))
        {
            // log << "loan after create: " << to_string(loan->getJson())
            //     << std::endl;
            BEAST_EXPECT(
                loan->isFlag(lsfLoanOverpayment) == createJtx.stx->isFlag(tfLoanOverpayment));
            BEAST_EXPECT(loan->at(sfLoanSequence) == loanSequence);
            BEAST_EXPECT(loan->at(sfBorrower) == borrower.id());
            BEAST_EXPECT(loan->at(sfLoanBrokerID) == broker.brokerID);
            BEAST_EXPECT(loan->at(sfLoanOriginationFee) == originationFeeAmount);
            BEAST_EXPECT(loan->at(sfLoanServiceFee) == serviceFeeAmount);
            BEAST_EXPECT(loan->at(sfLatePaymentFee) == lateFeeAmount);
            BEAST_EXPECT(loan->at(sfClosePaymentFee) == closeFeeAmount);
            BEAST_EXPECT(loan->at(sfOverpaymentFee) == *loanParams.overFee);
            BEAST_EXPECT(loan->at(sfInterestRate) == *loanParams.interest);
            BEAST_EXPECT(loan->at(sfLateInterestRate) == *loanParams.lateInterest);
            BEAST_EXPECT(loan->at(sfCloseInterestRate) == *loanParams.closeInterest);
            BEAST_EXPECT(loan->at(sfOverpaymentInterestRate) == *loanParams.overpaymentInterest);
            BEAST_EXPECT(loan->at(sfStartDate) == startDate);
            BEAST_EXPECT(loan->at(sfPaymentInterval) == *loanParams.payInterval);
            BEAST_EXPECT(loan->at(sfGracePeriod) == *loanParams.gracePd);
            BEAST_EXPECT(loan->at(sfPreviousPaymentDueDate) == 0);
            BEAST_EXPECT(loan->at(sfNextPaymentDueDate) == startDate + *loanParams.payInterval);
            BEAST_EXPECT(loan->at(sfPaymentRemaining) == *loanParams.payTotal);
            BEAST_EXPECT(
                loan->at(sfLoanScale) >=
                (broker.asset.integral()
                     ? 0
                     : std::max(broker.vaultScale(env), principalRequestAmount.exponent())));
            BEAST_EXPECT(loan->at(sfPrincipalOutstanding) == principalRequestAmount);
        }
 
        auto state = getCurrentState(env, broker, keylet, verifyLoanStatus);
 
        auto const loanProperties = computeLoanProperties(
            env.current()->rules(),
            broker.asset.raw(),
            state.principalOutstanding,
            state.interestRate,
            state.paymentInterval,
            state.paymentRemaining,
            broker.params.managementFeeRate,
            state.loanScale);
 
        verifyLoanStatus(
            0,
            startDate + *loanParams.payInterval,
            *loanParams.payTotal,
            state.loanScale,
            loanProperties.loanState.valueOutstanding,
            principalRequestAmount,
            loanProperties.loanState.managementFeeDue,
            loanProperties.periodicPayment,
            loanFlags | 0);
 
        // Manage the loan
        // no-op
        env(manage(lender, keylet.key, 0));
        {
            // no flags
            auto jt = manage(lender, keylet.key, 0);
            jt.removeMember(sfFlags.getName());
            env(jt);
        }
        // Only the lender can manage
        env(manage(evan, keylet.key, 0), Ter(tecNO_PERMISSION));
        // unknown flags
        env(manage(lender, keylet.key, tfLoanManageMask), Ter(temINVALID_FLAG));
        // combinations of flags are not allowed
        env(manage(lender, keylet.key, tfLoanUnimpair | tfLoanImpair), Ter(temINVALID_FLAG));
        env(manage(lender, keylet.key, tfLoanImpair | tfLoanDefault), Ter(temINVALID_FLAG));
        env(manage(lender, keylet.key, tfLoanUnimpair | tfLoanDefault), Ter(temINVALID_FLAG));
        env(manage(lender, keylet.key, tfLoanUnimpair | tfLoanImpair | tfLoanDefault),
            Ter(temINVALID_FLAG));
        // invalid loan ID
        env(manage(lender, broker.brokerID, tfLoanImpair), Ter(tecNO_ENTRY));
        // Loan is unimpaired, can't unimpair it again
        env(manage(lender, keylet.key, tfLoanUnimpair), Ter(tecNO_PERMISSION));
        // Loan is unimpaired, it can go into default, but only after it's past
        // due
        env(manage(lender, keylet.key, tfLoanDefault), Ter(tecTOO_SOON));
 
        // Check the vault
        bool const canImpair = canImpairLoan(env, broker, state);
        // Impair the loan, if possible
        env(manage(lender, keylet.key, tfLoanImpair),
            canImpair ? Ter(tesSUCCESS) : Ter(tecLIMIT_EXCEEDED));
        // Unimpair the loan
        env(manage(lender, keylet.key, tfLoanUnimpair),
            canImpair ? Ter(tesSUCCESS) : Ter(tecNO_PERMISSION));
 
        auto const nextDueDate = startDate + *loanParams.payInterval;
 
        env.close();
 
        verifyLoanStatus(
            0,
            nextDueDate,
            *loanParams.payTotal,
            loanProperties.loanScale,
            loanProperties.loanState.valueOutstanding,
            principalRequestAmount,
            loanProperties.loanState.managementFeeDue,
            loanProperties.periodicPayment,
            loanFlags | 0);
 
        // Can't delete the loan yet. It has payments remaining.
        env(del(lender, keylet.key), Ter(tecHAS_OBLIGATIONS));
 
        if (BEAST_EXPECT(toEndOfLife))
            toEndOfLife(keylet, verifyLoanStatus);
        env.close();
 
        // Verify the loan is at EOL
        if (auto loan = env.le(keylet); BEAST_EXPECT(loan))
        {
            BEAST_EXPECT(loan->at(sfPaymentRemaining) == 0);
            BEAST_EXPECT(loan->at(sfPrincipalOutstanding) == 0);
        }
        auto const borrowerStartingBalance = env.balance(borrower, broker.asset);
 
        // Try to delete the loan broker with an active loan
        env(loan_broker::del(lender, broker.brokerID), Ter(tecHAS_OBLIGATIONS));
        // Ensure the above tx doesn't get ordered after the LoanDelete and
        // delete our broker!
        env.close();
 
        // Test failure cases
        env(del(lender, keylet.key, tfLoanOverpayment), Ter(temINVALID_FLAG));
        env(del(evan, keylet.key), Ter(tecNO_PERMISSION));
        env(del(lender, broker.brokerID), Ter(tecNO_ENTRY));
 
        // Delete the loan
        // Either the borrower or the lender can delete the loan. Alternate
        // between who does it across tests.
        static unsigned kDeleteCounter = 0;
        auto const deleter = ((++kDeleteCounter % 2) != 0u) ? lender : borrower;
        env(del(deleter, keylet.key));
        env.close();
 
        PrettyAmount adjustment = broker.asset(0);
        if (deleter == borrower)
        {
            // Need to account for fees if the loan is in XRP
            if (broker.asset.native())
            {
                adjustment = env.current()->fees().base;
            }
        }
 
        // No loans left
        verifyLoanStatus.checkBroker(0, 0, *loanParams.interest, 1, 0, 0);
 
        BEAST_EXPECT(
            env.balance(borrower, broker.asset).value() ==
            borrowerStartingBalance.value() - adjustment);
        BEAST_EXPECT(env.ownerCount(borrower) == borrowerOwnerCount);
 
        if (auto const brokerSle = env.le(keylet::loanBroker(broker.brokerID));
            BEAST_EXPECT(brokerSle))
        {
            BEAST_EXPECT(brokerSle->at(sfOwnerCount) == 0);
        }
    }
 
    static std::string
    getCurrencyLabel(Asset const& asset)
    {
        if (asset.native())
            return "XRP";
        if (asset.holds<Issue>())
            return "IOU";
        if (asset.holds<MPTIssue>())
            return "MPT";
        return "Unknown";
    }

    template <class TAsset, std::size_t NAsset>
    void
    testCaseWrapper(
        jtx::Env& env,
        jtx::MPTTester& mptt,
        std::array<TAsset, NAsset> const& assets,
        BrokerInfo const& broker,
        Number const& loanAmount,
        int interestExponent)
    {
        using namespace jtx;
        using namespace lending;
 
        auto const& asset = broker.asset.raw();
        auto const currencyLabel = getCurrencyLabel(asset);
        auto const caseLabel = [&]() {
            std::stringstream ss;
            ss << "Lifecycle: " << loanAmount << " " << currencyLabel
               << " Scale interest to: " << interestExponent << " ";
            return ss.str();
        }();
        testcase << caseLabel;
 
        using namespace loan;
        using namespace std::chrono_literals;
        using d = NetClock::duration;
        using tp = NetClock::time_point;
 
        Account const issuer{"issuer"};
        // For simplicity, lender will be the sole actor for the vault &
        // brokers.
        Account const lender{"lender"};
        // Borrower only wants to borrow
        Account const borrower{"borrower"};
        // Evan will attempt to be naughty
        Account const evan{"evan"};
        // Do not fund alice
        Account const alice{"alice"};
 
        Number const principalRequest = broker.asset(loanAmount).value();
        Number const maxCoveredLoanValue = broker.params.maxCoveredLoanValue(0);
        BEAST_EXPECT(maxCoveredLoanValue == 1000 * 100 / 10);
        Number const maxCoveredLoanRequest = broker.asset(maxCoveredLoanValue).value();
        Number const totalVaultRequest = broker.asset(broker.params.vaultDeposit).value();
        Number const debtMaximumRequest = broker.asset(broker.params.debtMax).value();
 
        auto const loanSetFee = Fee(env.current()->fees().base * 2);
 
        auto const pseudoAcct = brokerPseudoAccount(env, broker, lender);
 
        auto const baseFee = env.current()->fees().base;
 
        auto badKeylet = keylet::vault(lender.id(), SeqProxy::rawSequence(env.seq(lender)));
        // Try some failure cases
        // flags are checked first
        env(set(evan, broker.brokerID, principalRequest, tfLoanSetMask),
            Sig(sfCounterpartySignature, lender),
            loanSetFee,
            Ter(temINVALID_FLAG));
 
        // field length validation
        // sfData: good length, bad account
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, borrower),
            kData(std::string(kMaxDataPayloadLength, 'X')),
            loanSetFee,
            Ter(tefBAD_AUTH));
        // sfData: too long
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, lender),
            kData(std::string(kMaxDataPayloadLength + 1, 'Y')),
            loanSetFee,
            Ter(temINVALID));
 
        // field range validation
        // sfOverpaymentFee: good value, bad account
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, borrower),
            kOverpaymentFee(kMaxOverpaymentFee),
            loanSetFee,
            Ter(tefBAD_AUTH));
        // sfOverpaymentFee: too big
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, lender),
            kOverpaymentFee(kMaxOverpaymentFee + 1),
            loanSetFee,
            Ter(temINVALID));
 
        // sfInterestRate: good value, bad account
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, borrower),
            kInterestRate(kMaxInterestRate),
            loanSetFee,
            Ter(tefBAD_AUTH));
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, borrower),
            kInterestRate(TenthBips32(0)),
            loanSetFee,
            Ter(tefBAD_AUTH));
        // sfInterestRate: too big
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, lender),
            kInterestRate(kMaxInterestRate + 1),
            loanSetFee,
            Ter(temINVALID));
        // sfInterestRate: too small
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, lender),
            kInterestRate(TenthBips32(-1)),
            loanSetFee,
            Ter(temINVALID));
 
        // sfLateInterestRate: good value, bad account
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, borrower),
            kLateInterestRate(kMaxLateInterestRate),
            loanSetFee,
            Ter(tefBAD_AUTH));
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, borrower),
            kLateInterestRate(TenthBips32(0)),
            loanSetFee,
            Ter(tefBAD_AUTH));
        // sfLateInterestRate: too big
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, lender),
            kLateInterestRate(kMaxLateInterestRate + 1),
            loanSetFee,
            Ter(temINVALID));
        // sfLateInterestRate: too small
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, lender),
            kLateInterestRate(TenthBips32(-1)),
            loanSetFee,
            Ter(temINVALID));
 
        // sfCloseInterestRate: good value, bad account
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, borrower),
            kCloseInterestRate(kMaxCloseInterestRate),
            loanSetFee,
            Ter(tefBAD_AUTH));
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, borrower),
            kCloseInterestRate(TenthBips32(0)),
            loanSetFee,
            Ter(tefBAD_AUTH));
        // sfCloseInterestRate: too big
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, lender),
            kCloseInterestRate(kMaxCloseInterestRate + 1),
            loanSetFee,
            Ter(temINVALID));
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, lender),
            kCloseInterestRate(TenthBips32(-1)),
            loanSetFee,
            Ter(temINVALID));
 
        // sfOverpaymentInterestRate: good value, bad account
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, borrower),
            kOverpaymentInterestRate(kMaxOverpaymentInterestRate),
            loanSetFee,
            Ter(tefBAD_AUTH));
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, borrower),
            kOverpaymentInterestRate(TenthBips32(0)),
            loanSetFee,
            Ter(tefBAD_AUTH));
        // sfOverpaymentInterestRate: too big
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, lender),
            kOverpaymentInterestRate(kMaxOverpaymentInterestRate + 1),
            loanSetFee,
            Ter(temINVALID));
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, lender),
            kOverpaymentInterestRate(TenthBips32(-1)),
            loanSetFee,
            Ter(temINVALID));
 
        // sfPaymentTotal: good value, bad account
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, borrower),
            kPaymentTotal(LoanSet::kMinPaymentTotal),
            loanSetFee,
            Ter(tefBAD_AUTH));
        // sfPaymentTotal: too small (there is no max)
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, lender),
            kPaymentTotal(LoanSet::kMinPaymentTotal - 1),
            loanSetFee,
            Ter(temINVALID));
 
        // sfPaymentInterval: good value, bad account
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, borrower),
            kPaymentInterval(LoanSet::kMinPaymentInterval),
            loanSetFee,
            Ter(tefBAD_AUTH));
        // sfPaymentInterval: too small (there is no max)
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, lender),
            kPaymentInterval(LoanSet::kMinPaymentInterval - 1),
            loanSetFee,
            Ter(temINVALID));
 
        // sfGracePeriod: good value, bad account
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, borrower),
            kPaymentInterval(LoanSet::kMinPaymentInterval * 2),
            kGracePeriod(LoanSet::kMinPaymentInterval * 2),
            loanSetFee,
            Ter(tefBAD_AUTH));
        // sfGracePeriod: larger than paymentInterval
        env(set(evan, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, lender),
            kPaymentInterval(LoanSet::kMinPaymentInterval * 2),
            kGracePeriod(LoanSet::kMinPaymentInterval * 3),
            loanSetFee,
            Ter(temINVALID));
 
        // insufficient fee - single sign
        env(set(borrower, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, lender),
            Ter(telINSUF_FEE_P));
        // insufficient fee - multisign
        env(signers(lender, 2, {{evan, 1}, {borrower, 1}}));
        env(signers(borrower, 2, {{evan, 1}, {lender, 1}}));
        env(set(borrower, broker.brokerID, principalRequest),
            kCounterparty(lender),
            Msig(evan, lender),
            Msig(sfCounterpartySignature, evan, borrower),
            Fee(env.current()->fees().base * 5 - 1),
            Ter(telINSUF_FEE_P));
        // Bad multisign signatures for borrower (Account)
        env(set(borrower, broker.brokerID, principalRequest),
            kCounterparty(lender),
            Msig(alice, issuer),
            Msig(sfCounterpartySignature, evan, borrower),
            Fee(env.current()->fees().base * 5),
            Ter(tefBAD_SIGNATURE));
        // Bad multisign signatures for issuer (Counterparty)
        env(set(borrower, broker.brokerID, principalRequest),
            kCounterparty(lender),
            Msig(evan, lender),
            Msig(sfCounterpartySignature, alice, issuer),
            Fee(env.current()->fees().base * 5 - 1),
            Ter(tefBAD_SIGNATURE));
        env(signers(lender, kNone));
        env(signers(borrower, kNone));
        // multisign sufficient fee, but no signers set up
        env(set(borrower, broker.brokerID, principalRequest),
            kCounterparty(lender),
            Msig(evan, lender),
            Msig(sfCounterpartySignature, evan, borrower),
            Fee(env.current()->fees().base * 5),
            Ter(tefNOT_MULTI_SIGNING));
        // not the broker owner, no counterparty, not signed by broker
        // owner
        env(set(borrower, broker.brokerID, principalRequest),
            Sig(sfCounterpartySignature, evan),
            loanSetFee,
            Ter(tefBAD_AUTH));
        // not the broker owner, counterparty is borrower
        env(set(evan, broker.brokerID, principalRequest),
            kCounterparty(borrower),
            Sig(sfCounterpartySignature, borrower),
            loanSetFee,
            Ter(tecNO_PERMISSION));
        // not a LoanBroker object, no counterparty
        env(set(lender, badKeylet.key, principalRequest),
            Sig(sfCounterpartySignature, evan),
            loanSetFee,
            Ter(temBAD_SIGNER));
        // not a LoanBroker object, counterparty is valid
        env(set(lender, badKeylet.key, principalRequest),
            kCounterparty(borrower),
            Sig(sfCounterpartySignature, borrower),
            loanSetFee,
            Ter(tecNO_ENTRY));
        // borrower doesn't exist
        env(set(lender, broker.brokerID, principalRequest),
            kCounterparty(alice),
            Sig(sfCounterpartySignature, alice),
            loanSetFee,
            Ter(terNO_ACCOUNT));
 
        // Request more funds than the vault has available
        env(set(evan, broker.brokerID, totalVaultRequest + 1),
            Sig(sfCounterpartySignature, lender),
            loanSetFee,
            Ter(tecINSUFFICIENT_FUNDS));
 
        // Request more funds than the broker's first-loss capital can
        // cover.
        env(set(evan, broker.brokerID, maxCoveredLoanRequest + 1),
            Sig(sfCounterpartySignature, lender),
            loanSetFee,
            Ter(tecINSUFFICIENT_FUNDS));
 
        // Frozen trust line / locked MPT issuance
        // XRP can not be frozen, but run through the loop anyway to test
        // the tecLIMIT_EXCEEDED case
        {
            auto const brokerSle = env.le(keylet::loanBroker(broker.brokerID));
            if (!BEAST_EXPECT(brokerSle))
                return;
 
            auto const vaultPseudo = [&]() {
                auto const vaultSle = env.le(keylet::vault(brokerSle->at(sfVaultID)));
                if (!BEAST_EXPECT(vaultSle))
                {
                    // This will be wrong, but the test has failed anyway.
                    return Account{lender};
                }
                auto vaultPseudo = Account("Vault pseudo-account", vaultSle->at(sfAccount));
                return vaultPseudo;
            }();
 
            auto const [freeze, deepfreeze, unfreeze, expectedResult] =
                [&]() -> std::tuple<
                          std::function<void(Account const& holder)>,
                          std::function<void(Account const& holder)>,
                          std::function<void(Account const& holder)>,
                          TER> {
                // Freeze / lock the asset
                std::function<void(Account const& holder)> const empty;
                if (broker.asset.native())
                {
                    // XRP can't be frozen
                    return std::make_tuple(empty, empty, empty, tesSUCCESS);
                }
                if (broker.asset.holds<Issue>())
                {
                    auto freeze = [&](Account const& holder) {
                        env(trust(issuer, holder[iouCurrency_](0), tfSetFreeze));
                    };
                    auto deepfreeze = [&](Account const& holder) {
                        env(trust(issuer, holder[iouCurrency_](0), tfSetFreeze | tfSetDeepFreeze));
                    };
                    auto unfreeze = [&](Account const& holder) {
                        env(trust(
                            issuer, holder[iouCurrency_](0), tfClearFreeze | tfClearDeepFreeze));
                    };
                    return std::make_tuple(freeze, deepfreeze, unfreeze, tecFROZEN);
                }
 
                auto freeze = [&](Account const& holder) {
                    mptt.set({.account = issuer, .holder = holder, .flags = tfMPTLock});
                };
                auto unfreeze = [&](Account const& holder) {
                    mptt.set({.account = issuer, .holder = holder, .flags = tfMPTUnlock});
                };
                return std::make_tuple(freeze, empty, unfreeze, tecLOCKED);
            }();
 
            // Try freezing the accounts that can't be frozen
            if (freeze)
            {
                for (auto const& account : {vaultPseudo, evan})
                {
                    // Freeze the account
                    freeze(account);
 
                    // Try to create a loan with a frozen line
                    env(set(evan, broker.brokerID, debtMaximumRequest),
                        Sig(sfCounterpartySignature, lender),
                        loanSetFee,
                        Ter(expectedResult));
 
                    // Unfreeze the account
                    BEAST_EXPECT(unfreeze);
                    unfreeze(account);
 
                    // Ensure the line is unfrozen with a request that is fine
                    // except too it requests more principal than the broker can
                    // carry
                    env(set(evan, broker.brokerID, debtMaximumRequest + 1),
                        Sig(sfCounterpartySignature, lender),
                        loanSetFee,
                        Ter(tecLIMIT_EXCEEDED));
                }
            }
 
            // Deep freeze the borrower, which prevents them from receiving
            // funds
            if (deepfreeze)
            {
                // Make sure evan has a trust line that so the issuer can
                // freeze it. (Don't need to do this for the borrower,
                // because LoanSet will create a line to the borrower
                // automatically.)
                env(trust(evan, issuer[iouCurrency_](100'000)));
 
                for (auto const& account : {// these accounts can't be frozen, which deep freeze
                                            // implies
                                            vaultPseudo,
                                            evan,
                                            // these accounts can't be deep frozen
                                            lender})
                {
                    // Freeze evan
                    deepfreeze(account);
 
                    // Try to create a loan with a deep frozen line
                    env(set(evan, broker.brokerID, debtMaximumRequest),
                        Sig(sfCounterpartySignature, lender),
                        loanSetFee,
                        Ter(expectedResult));
 
                    // Unfreeze evan
                    BEAST_EXPECT(unfreeze);
                    unfreeze(account);
 
                    // Ensure the line is unfrozen with a request that is fine
                    // except too it requests more principal than the broker can
                    // carry
                    env(set(evan, broker.brokerID, debtMaximumRequest + 1),
                        Sig(sfCounterpartySignature, lender),
                        loanSetFee,
                        Ter(tecLIMIT_EXCEEDED));
                }
            }
        }
 
        // Finally! Create a loan
 
        auto coverAvailable = [&env, this](uint256 const& brokerID, Number const& expected) {
            if (auto const brokerSle = env.le(keylet::loanBroker(brokerID));
                BEAST_EXPECT(brokerSle))
            {
                auto const available = brokerSle->at(sfCoverAvailable);
                BEAST_EXPECT(available == expected);
                return available;
            }
            return Number{};
        };
        auto getDefaultInfo = [&env, this](LoanState const& state, BrokerInfo const& broker) {
            if (auto const brokerSle = env.le(keylet::loanBroker(broker.brokerID));
                BEAST_EXPECT(brokerSle))
            {
                BEAST_EXPECT(
                    state.loanScale >=
                    (broker.asset.integral()
                         ? 0
                         : std::max(
                               broker.vaultScale(env), state.principalOutstanding.exponent())));
                NumberRoundModeGuard const mg(Number::RoundingMode::Upward);
                auto const defaultAmount = roundToAsset(
                    broker.asset,
                    std::min(
                        tenthBipsOfValue(
                            tenthBipsOfValue(
                                brokerSle->at(sfDebtTotal), broker.params.coverRateMin),
                            broker.params.coverRateLiquidation),
                        state.totalValue - state.managementFeeOutstanding),
                    state.loanScale);
                return std::make_pair(defaultAmount, brokerSle->at(sfOwner));
            }
            return std::make_pair(Number{}, AccountID{});
        };
        auto replenishCover = [&env, &coverAvailable](
                                  BrokerInfo const& broker,
                                  AccountID const& brokerAcct,
                                  Number const& startingCoverAvailable,
                                  Number const& amountToBeCovered) {
            coverAvailable(broker.brokerID, startingCoverAvailable - amountToBeCovered);
            env(loan_broker::coverDeposit(
                brokerAcct, broker.brokerID, STAmount{broker.asset, amountToBeCovered}));
            coverAvailable(broker.brokerID, startingCoverAvailable);
            env.close();
        };
 
        auto defaultImmediately = [&](std::uint32_t baseFlag, bool impair = true) {
            return [&, impair, baseFlag](
                       Keylet const& loanKeylet, VerifyLoanStatus const& verifyLoanStatus) {
                // toEndOfLife
                //
                // Default the loan
 
                // Initialize values with the current state
                auto state = getCurrentState(env, broker, loanKeylet, verifyLoanStatus);
                BEAST_EXPECT(state.flags == baseFlag);
 
                auto const& broker = verifyLoanStatus.broker;
                auto const startingCoverAvailable = coverAvailable(
                    broker.brokerID, broker.asset(broker.params.coverDeposit).number());
 
                if (impair)
                {
                    // Check the vault
                    bool const canImpair = canImpairLoan(env, broker, state);
                    // Impair the loan, if possible
                    env(manage(lender, loanKeylet.key, tfLoanImpair),
                        canImpair ? Ter(tesSUCCESS) : Ter(tecLIMIT_EXCEEDED));
 
                    if (canImpair)
                    {
                        state.flags |= tfLoanImpair;
                        state.nextPaymentDate = env.now().time_since_epoch().count();
 
                        // Once the loan is impaired, it can't be impaired again
                        env(manage(lender, loanKeylet.key, tfLoanImpair), Ter(tecNO_PERMISSION));
                    }
                    verifyLoanStatus(state);
                }
 
                auto const nextDueDate = tp{d{state.nextPaymentDate}};
 
                // Can't default the loan yet. The grace period hasn't
                // expired
                env(manage(lender, loanKeylet.key, tfLoanDefault), Ter(tecTOO_SOON));
 
                // Let some time pass so that the loan can be
                // defaulted
                env.close(nextDueDate + 60s);
 
                auto const [amountToBeCovered, brokerAcct] = getDefaultInfo(state, broker);
 
                // Default the loan
                env(manage(lender, loanKeylet.key, tfLoanDefault));
                env.close();
 
                // The LoanBroker just lost some of it's first-loss capital.
                // Replenish it.
                replenishCover(broker, brokerAcct, startingCoverAvailable, amountToBeCovered);
 
                state.flags |= tfLoanDefault;
                state.paymentRemaining = 0;
                state.totalValue = 0;
                state.principalOutstanding = 0;
                state.managementFeeOutstanding = 0;
                state.nextPaymentDate = 0;
                verifyLoanStatus(state);
 
                // Once a loan is defaulted, it can't be managed
                env(manage(lender, loanKeylet.key, tfLoanUnimpair), Ter(tecNO_PERMISSION));
                env(manage(lender, loanKeylet.key, tfLoanImpair), Ter(tecNO_PERMISSION));
                // Can't make a payment on it either
                env(pay(borrower, loanKeylet.key, broker.asset(300)), Ter(tecKILLED));
            };
        };
 
        auto singlePayment = [&](Keylet const& loanKeylet,
                                 VerifyLoanStatus const& verifyLoanStatus,
                                 LoanState& state,
                                 STAmount const& payoffAmount,
                                 std::uint32_t numPayments,
                                 std::uint32_t baseFlag,
                                 std::uint32_t txFlags) {
            // toEndOfLife
            //
            verifyLoanStatus(state);
 
            // Send some bogus pay transactions
            env(pay(borrower, keylet::loan(uint256(0)).key, broker.asset(10), txFlags),
                Ter(temINVALID));
            // broker.asset(80) is less than a single payment, but all these
            // checks fail before that matters
            env(pay(borrower, loanKeylet.key, broker.asset(-80), txFlags), Ter(temBAD_AMOUNT));
            env(pay(borrower, broker.brokerID, broker.asset(80), txFlags), Ter(tecNO_ENTRY));
            env(pay(evan, loanKeylet.key, broker.asset(80), txFlags), Ter(tecNO_PERMISSION));
 
            // TODO: Write a general "isFlag" function? See STObject::isFlag.
            // Maybe add a static overloaded member?
            if (!(state.flags & lsfLoanOverpayment))
            {
                // If the loan does not allow overpayments, send a payment that
                // tries to make an overpayment. Do not include `txFlags`, so we
                // don't end up duplicating the next test transaction.
                //
                // fixCleanup3_1_3 gates tfLoanOverpayment as a valid flag:
                // with fix on → preflight passes, apply returns tecNO_PERMISSION;
                // with fix off → preflight rejects the flag, returns temINVALID_FLAG.
                bool const hasFix313 = env.current()->rules().enabled(fixCleanup3_1_3);
                STAmount const overpayAmount{broker.asset, state.periodicPayment * Number{15, -1}};
                XRPAmount const overpayFee{
                    baseFee * (Number{15, -1} / kLoanPaymentsPerFeeIncrement + 1)};
                env(pay(borrower, loanKeylet.key, overpayAmount, tfLoanOverpayment),
                    Fee(overpayFee),
                    Ter(hasFix313 ? TER{tecNO_PERMISSION} : TER{temINVALID_FLAG}));
 
                if (hasFix313)
                {
                    env.disableFeature(fixCleanup3_1_3);
                    env(pay(borrower, loanKeylet.key, overpayAmount, tfLoanOverpayment),
                        Fee(overpayFee),
                        Ter(temINVALID_FLAG));
                    env.enableFeature(fixCleanup3_1_3);
                }
            }
            // Try to send a payment marked as multiple mutually exclusive
            // payment types. Do not include `txFlags`, so we don't duplicate
            // the prior test transaction.
            env(pay(borrower,
                    loanKeylet.key,
                    broker.asset(state.periodicPayment * 2),
                    tfLoanLatePayment | tfLoanFullPayment),
                Ter(temINVALID_FLAG));
            env(pay(borrower,
                    loanKeylet.key,
                    broker.asset(state.periodicPayment * 2),
                    tfLoanLatePayment | tfLoanOverpayment),
                Ter(temINVALID_FLAG));
            env(pay(borrower,
                    loanKeylet.key,
                    broker.asset(state.periodicPayment * 2),
                    tfLoanOverpayment | tfLoanFullPayment),
                Ter(temINVALID_FLAG));
            env(pay(borrower,
                    loanKeylet.key,
                    broker.asset(state.periodicPayment * 2),
                    tfLoanLatePayment | tfLoanOverpayment | tfLoanFullPayment),
                Ter(temINVALID_FLAG));
 
            {
                auto const otherAsset =
                    broker.asset.raw() == assets[0].raw() ? assets[1] : assets[0];
                env(pay(borrower, loanKeylet.key, otherAsset(100), txFlags), Ter(tecWRONG_ASSET));
            }
 
            // Amount doesn't cover a single payment
            env(pay(borrower, loanKeylet.key, STAmount{broker.asset, 1}, txFlags),
                Ter(tecINSUFFICIENT_PAYMENT));
 
            // Get the balance after these failed transactions take
            // fees
            auto const borrowerBalanceBeforePayment = env.balance(borrower, broker.asset);
 
            BEAST_EXPECT(payoffAmount > state.principalOutstanding);
            // Try to pay a little extra to show that it's _not_
            // taken
            auto const transactionAmount = payoffAmount + broker.asset(10);
 
            // Send a transaction that tries to pay more than the borrowers's
            // balance
            XRPAmount const badFee{
                baseFee *
                (borrowerBalanceBeforePayment.number() * 2 / state.periodicPayment /
                     kLoanPaymentsPerFeeIncrement +
                 1)};
            env(pay(borrower,
                    loanKeylet.key,
                    STAmount{broker.asset, borrowerBalanceBeforePayment.number() * 2},
                    txFlags),
                Fee(badFee),
                Ter(tecINSUFFICIENT_FUNDS));
 
            XRPAmount const goodFee{baseFee * (numPayments / kLoanPaymentsPerFeeIncrement + 1)};
            env(pay(borrower, loanKeylet.key, transactionAmount, txFlags), Fee(goodFee));
 
            env.close();
 
            // log << env.meta()->getJson() << std::endl;
 
            // Need to account for fees if the loan is in XRP
            PrettyAmount adjustment = broker.asset(0);
            if (broker.asset.native())
            {
                adjustment = badFee + goodFee;
            }
 
            state.paymentRemaining = 0;
            state.principalOutstanding = 0;
            state.totalValue = 0;
            state.managementFeeOutstanding = 0;
            state.previousPaymentDate =
                state.nextPaymentDate + (state.paymentInterval * (numPayments - 1));
            state.nextPaymentDate = 0;
            verifyLoanStatus(state);
 
            verifyLoanStatus.checkPayment(
                state.loanScale, borrower, borrowerBalanceBeforePayment, payoffAmount, adjustment);
 
            // Can't impair or default a paid off loan
            env(manage(lender, loanKeylet.key, tfLoanImpair), Ter(tecNO_PERMISSION));
            env(manage(lender, loanKeylet.key, tfLoanDefault), Ter(tecNO_PERMISSION));
        };
 
        auto fullPayment = [&](std::uint32_t baseFlag) {
            return [&, baseFlag](
                       Keylet const& loanKeylet, VerifyLoanStatus const& verifyLoanStatus) {
                // toEndOfLife
                //
                auto state = getCurrentState(env, broker, loanKeylet, verifyLoanStatus);
                env.close(state.startDate + 20s);
                auto const loanAge = (env.now() - state.startDate).count();
                BEAST_EXPECT(loanAge == 30);
 
                // Full payoff amount will consist of
                // 1. principal outstanding (1000)
                // 2. accrued interest (at 12%)
                // 3. prepayment penalty (closeInterest at 3.6%)
                // 4. close payment fee (4)
                // Calculate these values without the helper functions
                // to verify they're working correctly The numbers in
                // the below BEAST_EXPECTs may not hold across assets.
                Number const interval = state.paymentInterval;
                auto const periodicRate = interval * Number(12, -2) / kSecondsInYear;
                BEAST_EXPECT(
                    periodicRate == Number(2283105022831050228ULL, -24, Number::Normalized{}));
                STAmount const principalOutstanding{broker.asset, state.principalOutstanding};
                STAmount const accruedInterest{
                    broker.asset, state.principalOutstanding * periodicRate * loanAge / interval};
                BEAST_EXPECT(accruedInterest == broker.asset(Number(1141552511415525, -19)));
                STAmount const prepaymentPenalty{
                    broker.asset, state.principalOutstanding * Number(36, -3)};
                BEAST_EXPECT(prepaymentPenalty == broker.asset(36));
                STAmount const closePaymentFee = broker.asset(4);
                auto const payoffAmount = roundToScale(
                    principalOutstanding + accruedInterest + prepaymentPenalty + closePaymentFee,
                    state.loanScale);
                BEAST_EXPECT(
                    payoffAmount ==
                    roundToAsset(
                        broker.asset,
                        broker.asset(Number(1040000114155251, -12)).number(),
                        state.loanScale));
 
                // The terms of this loan actually make the early payoff
                // more expensive than just making payments
                BEAST_EXPECT(
                    payoffAmount >
                    state.paymentRemaining * (state.periodicPayment + broker.asset(2).value()));
 
                singlePayment(
                    loanKeylet,
                    verifyLoanStatus,
                    state,
                    payoffAmount,
                    1,
                    baseFlag,
                    tfLoanFullPayment);
            };
        };
 
        auto combineAllPayments = [&](std::uint32_t baseFlag) {
            return
                [&, baseFlag](Keylet const& loanKeylet, VerifyLoanStatus const& verifyLoanStatus) {
                    // toEndOfLife
                    //
 
                    auto state = getCurrentState(env, broker, loanKeylet, verifyLoanStatus);
                    env.close();
 
                    BEAST_EXPECT(
                        STAmount(broker.asset, state.periodicPayment) ==
                        broker.asset(Number(8333457002039338267, -17)));
 
                    // Make all the payments in one transaction
                    // service fee is 2
                    auto const startingPayments = state.paymentRemaining;
                    STAmount const payoffAmount = [&]() {
                        NumberRoundModeGuard const mg(Number::RoundingMode::Upward);
                        auto const rawPayoff =
                            startingPayments * (state.periodicPayment + broker.asset(2).value());
                        STAmount payoffAmount{broker.asset, rawPayoff};
                        BEAST_EXPECTS(
                            payoffAmount == broker.asset(Number(1024014840244721, -12)),
                            to_string(payoffAmount));
                        BEAST_EXPECT(payoffAmount > state.principalOutstanding);
 
                        payoffAmount = roundToScale(payoffAmount, state.loanScale);
 
                        return payoffAmount;
                    }();
 
                    auto const totalPayoffValue =
                        state.totalValue + startingPayments * broker.asset(2).value();
                    STAmount const totalPayoffAmount{broker.asset, totalPayoffValue};
 
                    BEAST_EXPECTS(
                        totalPayoffAmount == payoffAmount,
                        "Payoff amount: " + to_string(payoffAmount) +
                            ". Total Value: " + to_string(totalPayoffAmount));
 
                    singlePayment(
                        loanKeylet,
                        verifyLoanStatus,
                        state,
                        payoffAmount,
                        state.paymentRemaining,
                        baseFlag,
                        0);
                };
        };
 
        // There are a lot of fields that can be set on a loan, but most
        // of them only affect the "math" when a payment is made. The
        // only one that really affects behavior is the
        // `tfLoanOverpayment` flag.
        lifecycle(
            caseLabel,
            "Loan overpayment allowed - Impair and Default",
            env,
            loanAmount,
            interestExponent,
            lender,
            borrower,
            evan,
            broker,
            pseudoAcct,
            tfLoanOverpayment,
            defaultImmediately(lsfLoanOverpayment));
 
        lifecycle(
            caseLabel,
            "Loan overpayment prohibited - Impair and Default",
            env,
            loanAmount,
            interestExponent,
            lender,
            borrower,
            evan,
            broker,
            pseudoAcct,
            0,
            defaultImmediately(0));
 
        lifecycle(
            caseLabel,
            "Loan overpayment allowed - Default without Impair",
            env,
            loanAmount,
            interestExponent,
            lender,
            borrower,
            evan,
            broker,
            pseudoAcct,
            tfLoanOverpayment,
            defaultImmediately(lsfLoanOverpayment, false));
 
        lifecycle(
            caseLabel,
            "Loan overpayment prohibited - Default without Impair",
            env,
            loanAmount,
            interestExponent,
            lender,
            borrower,
            evan,
            broker,
            pseudoAcct,
            0,
            defaultImmediately(0, false));
 
        lifecycle(
            caseLabel,
            "Loan overpayment prohibited - Pay off immediately",
            env,
            loanAmount,
            interestExponent,
            lender,
            borrower,
            evan,
            broker,
            pseudoAcct,
            0,
            fullPayment(0));
 
        lifecycle(
            caseLabel,
            "Loan overpayment allowed - Pay off immediately",
            env,
            loanAmount,
            interestExponent,
            lender,
            borrower,
            evan,
            broker,
            pseudoAcct,
            tfLoanOverpayment,
            fullPayment(lsfLoanOverpayment));
 
        lifecycle(
            caseLabel,
            "Loan overpayment prohibited - Combine all payments",
            env,
            loanAmount,
            interestExponent,
            lender,
            borrower,
            evan,
            broker,
            pseudoAcct,
            0,
            combineAllPayments(0));
 
        lifecycle(
            caseLabel,
            "Loan overpayment allowed - Combine all payments",
            env,
            loanAmount,
            interestExponent,
            lender,
            borrower,
            evan,
            broker,
            pseudoAcct,
            tfLoanOverpayment,
            combineAllPayments(lsfLoanOverpayment));
 
        lifecycle(
            caseLabel,
            "Loan overpayment prohibited - Make payments",
            env,
            loanAmount,
            interestExponent,
            lender,
            borrower,
            evan,
            broker,
            pseudoAcct,
            0,
            [&](Keylet const& loanKeylet, VerifyLoanStatus const& verifyLoanStatus) {
                // toEndOfLife
                //
                // Draw and make multiple payments
                auto state = getCurrentState(env, broker, loanKeylet, verifyLoanStatus);
                BEAST_EXPECT(state.flags == 0);
                env.close();
 
                verifyLoanStatus(state);
 
                env.close(state.startDate + 20s);
                auto const loanAge = (env.now() - state.startDate).count();
                BEAST_EXPECT(loanAge == 30);
 
                // Periodic payment amount will consist of
                // 1. principal outstanding (1000)
                // 2. interest interest rate (at 12%)
                // 3. payment interval (600s)
                // 4. loan service fee (2)
                // Calculate these values without the helper functions
                // to verify they're working correctly The numbers in
                // the below BEAST_EXPECTs may not hold across assets.
                Number const interval = state.paymentInterval;
                auto const periodicRate = interval * Number(12, -2) / kSecondsInYear;
                BEAST_EXPECT(
                    periodicRate == Number(2283105022831050228, -24, Number::Normalized{}));
                STAmount const roundedPeriodicPayment{
                    broker.asset,
                    roundPeriodicPayment(broker.asset, state.periodicPayment, state.loanScale)};
 
                testcase << currencyLabel << " Payment components: "
                         << "Payments remaining, rawInterest, rawPrincipal, "
                            "rawMFee, trackedValueDelta, trackedPrincipalDelta, "
                            "trackedInterestDelta, trackedMgmtFeeDelta, special";
 
                auto const serviceFee = broker.asset(2);
 
                BEAST_EXPECT(
                    roundedPeriodicPayment ==
                    roundToScale(
                        broker.asset(
                            Number(8333457002039338267, -17), Number::RoundingMode::Upward),
                        state.loanScale,
                        Number::RoundingMode::Upward));
                // 83334570.01162141
                // Include the service fee
                STAmount const totalDue = roundToScale(
                    roundedPeriodicPayment + serviceFee,
                    state.loanScale,
                    Number::RoundingMode::Upward);
                // Only check the first payment since the rounding
                // may drift as payments are made
                BEAST_EXPECT(
                    totalDue ==
                    roundToScale(
                        broker.asset(
                            Number(8533457002039338267, -17), Number::RoundingMode::Upward),
                        state.loanScale,
                        Number::RoundingMode::Upward));
 
                {
                    auto const raw = computeTheoreticalLoanState(
                        env.current()->rules(),
                        state.periodicPayment,
                        periodicRate,
                        state.paymentRemaining,
                        broker.params.managementFeeRate);
                    auto const rounded = constructLoanState(
                        state.totalValue,
                        state.principalOutstanding,
                        state.managementFeeOutstanding);
                    testcase << currencyLabel << " Loan starting state: " << state.paymentRemaining
                             << ", " << raw.interestDue << ", " << raw.principalOutstanding << ", "
                             << raw.managementFeeDue << ", " << rounded.valueOutstanding << ", "
                             << rounded.principalOutstanding << ", " << rounded.interestDue << ", "
                             << rounded.managementFeeDue;
                }
 
                // Try to pay a little extra to show that it's _not_
                // taken
                STAmount const transactionAmount =
                    STAmount{broker.asset, totalDue} + broker.asset(10);
                // Only check the first payment since the rounding
                // may drift as payments are made
                BEAST_EXPECT(
                    transactionAmount ==
                    roundToScale(
                        broker.asset(Number(9533457002039400, -14), Number::RoundingMode::Upward),
                        state.loanScale,
                        Number::RoundingMode::Upward));
 
                auto const initialState = state;
                xrpl::detail::PaymentComponents totalPaid{
                    .trackedValueDelta = 0,
                    .trackedPrincipalDelta = 0,
                    .trackedManagementFeeDelta = 0};
                Number totalInterestPaid = 0;
                std::size_t totalPaymentsMade = 0;
 
                xrpl::LoanState currentTrueState = computeTheoreticalLoanState(
                    env.current()->rules(),
                    state.periodicPayment,
                    periodicRate,
                    state.paymentRemaining,
                    broker.params.managementFeeRate);
 
                while (state.paymentRemaining > 0)
                {
                    // Compute the expected principal amount
                    auto const paymentComponents = xrpl::detail::computePaymentComponents(
                        env.current()->rules(),
                        broker.asset.raw(),
                        state.loanScale,
                        state.totalValue,
                        state.principalOutstanding,
                        state.managementFeeOutstanding,
                        state.periodicPayment,
                        periodicRate,
                        state.paymentRemaining,
                        broker.params.managementFeeRate);
 
                    BEAST_EXPECTS(
                        paymentComponents.specialCase == xrpl::detail::PaymentSpecialCase::Final ||
                            paymentComponents.trackedValueDelta <= roundedPeriodicPayment,
                        "Delta: " + to_string(paymentComponents.trackedValueDelta) +
                            ", periodic payment: " + to_string(roundedPeriodicPayment));
 
                    xrpl::LoanState const nextTrueState = computeTheoreticalLoanState(
                        env.current()->rules(),
                        state.periodicPayment,
                        periodicRate,
                        state.paymentRemaining - 1,
                        broker.params.managementFeeRate);
                    xrpl::detail::LoanStateDeltas const deltas = currentTrueState - nextTrueState;
 
                    testcase << currencyLabel << " Payment components: " << state.paymentRemaining
                             << ", " << deltas.interest << ", " << deltas.principal << ", "
                             << deltas.managementFee << ", " << paymentComponents.trackedValueDelta
                             << ", " << paymentComponents.trackedPrincipalDelta << ", "
                             << paymentComponents.trackedInterestPart() << ", "
                             << paymentComponents.trackedManagementFeeDelta << ", "
                             << [&]() -> char const* {
                        if (paymentComponents.specialCase ==
                            ::xrpl::detail::PaymentSpecialCase::Final)
                            return "final";
                        if (paymentComponents.specialCase ==
                            ::xrpl::detail::PaymentSpecialCase::Extra)
                            return "extra";
                        return "none";
                    }();
 
                    auto const totalDueAmount = STAmount{
                        broker.asset, paymentComponents.trackedValueDelta + serviceFee.number()};
 
                    // Due to the rounding algorithms to keep the interest and
                    // principal in sync with "true" values, the computed amount
                    // may be a little less than the rounded fixed payment
                    // amount. For integral types, the difference should be < 3
                    // (1 unit for each of the interest and management fee). For
                    // IOUs, the difference should be after the 8th digit.
                    Number const diff = totalDue - totalDueAmount;
                    BEAST_EXPECT(
                        paymentComponents.specialCase == xrpl::detail::PaymentSpecialCase::Final ||
                        diff == beast::kZero ||
                        (diff > beast::kZero &&
                         ((broker.asset.integral() && (static_cast<Number>(diff) < 3)) ||
                          (state.loanScale - diff.exponent() > 13))));
 
                    BEAST_EXPECT(
                        paymentComponents.trackedValueDelta ==
                        paymentComponents.trackedPrincipalDelta +
                            paymentComponents.trackedInterestPart() +
                            paymentComponents.trackedManagementFeeDelta);
                    BEAST_EXPECT(
                        paymentComponents.specialCase == xrpl::detail::PaymentSpecialCase::Final ||
                        paymentComponents.trackedValueDelta <= roundedPeriodicPayment);
 
                    BEAST_EXPECT(
                        state.paymentRemaining < 12 ||
                        roundToAsset(
                            broker.asset,
                            deltas.principal,
                            state.loanScale,
                            Number::RoundingMode::Upward) ==
                            roundToScale(
                                broker.asset(
                                    Number(8333228691531218890, -17), Number::RoundingMode::Upward),
                                state.loanScale,
                                Number::RoundingMode::Upward));
                    BEAST_EXPECT(
                        paymentComponents.trackedPrincipalDelta >= beast::kZero &&
                        paymentComponents.trackedPrincipalDelta <= state.principalOutstanding);
                    BEAST_EXPECT(
                        paymentComponents.specialCase != xrpl::detail::PaymentSpecialCase::Final ||
                        paymentComponents.trackedPrincipalDelta == state.principalOutstanding);
                    BEAST_EXPECT(
                        paymentComponents.specialCase == xrpl::detail::PaymentSpecialCase::Final ||
                        (state.periodicPayment.exponent() -
                         (deltas.principal + deltas.interest + deltas.managementFee -
                          state.periodicPayment)
                             .exponent()) > 14);
 
                    auto const borrowerBalanceBeforePayment = env.balance(borrower, broker.asset);
 
                    if (canImpairLoan(env, broker, state))
                    {
                        // Making a payment will unimpair the loan
                        env(manage(lender, loanKeylet.key, tfLoanImpair));
                    }
 
                    env.close();
 
                    // Make the payment
                    env(pay(borrower, loanKeylet.key, transactionAmount));
 
                    env.close();
 
                    // Need to account for fees if the loan is in XRP
                    PrettyAmount adjustment = broker.asset(0);
                    if (broker.asset.native())
                    {
                        adjustment = env.current()->fees().base;
                    }
 
                    // Check the result
                    verifyLoanStatus.checkPayment(
                        state.loanScale,
                        borrower,
                        borrowerBalanceBeforePayment,
                        totalDueAmount,
                        adjustment);
 
                    --state.paymentRemaining;
                    state.previousPaymentDate = state.nextPaymentDate;
                    if (paymentComponents.specialCase == xrpl::detail::PaymentSpecialCase::Final)
                    {
                        state.paymentRemaining = 0;
                        state.nextPaymentDate = 0;
                    }
                    else
                    {
                        state.nextPaymentDate += state.paymentInterval;
                    }
                    state.principalOutstanding -= paymentComponents.trackedPrincipalDelta;
                    state.managementFeeOutstanding -= paymentComponents.trackedManagementFeeDelta;
                    state.totalValue -= paymentComponents.trackedValueDelta;
 
                    verifyLoanStatus(state);
 
                    totalPaid.trackedValueDelta += paymentComponents.trackedValueDelta;
                    totalPaid.trackedPrincipalDelta += paymentComponents.trackedPrincipalDelta;
                    totalPaid.trackedManagementFeeDelta +=
                        paymentComponents.trackedManagementFeeDelta;
                    totalInterestPaid += paymentComponents.trackedInterestPart();
                    ++totalPaymentsMade;
 
                    currentTrueState = nextTrueState;
                }
 
                // Loan is paid off
                BEAST_EXPECT(state.paymentRemaining == 0);
                BEAST_EXPECT(state.principalOutstanding == 0);
 
                // Make sure all the payments add up
                BEAST_EXPECT(totalPaid.trackedValueDelta == initialState.totalValue);
                BEAST_EXPECT(totalPaid.trackedPrincipalDelta == initialState.principalOutstanding);
                BEAST_EXPECT(
                    totalPaid.trackedManagementFeeDelta == initialState.managementFeeOutstanding);
                // This is almost a tautology given the previous checks, but
                // check it anyway for completeness.
                BEAST_EXPECT(
                    totalInterestPaid ==
                    initialState.totalValue -
                        (initialState.principalOutstanding +
                         initialState.managementFeeOutstanding));
                BEAST_EXPECT(totalPaymentsMade == initialState.paymentRemaining);
 
                // Can't impair or default a paid off loan
                env(manage(lender, loanKeylet.key, tfLoanImpair), Ter(tecNO_PERMISSION));
                env(manage(lender, loanKeylet.key, tfLoanDefault), Ter(tecNO_PERMISSION));
            });
 
#if LOAN_TODO
        // TODO
 
        /*
        LoanPay fails with tecINVARIANT_FAILED  error when loan_broker(also
        borrower) tries to do the payment. Here's the scenario: Create a XRP
        loan with loan broker as borrower, loan origination fee and loan service
        fee. Loan broker makes the first payment with periodic payment and loan
        service fee.
        */
 
        auto time = [&](std::string label, std::function<void()> timed) {
            if (!BEAST_EXPECT(timed))
                return;
 
            using clock_type = std::chrono::steady_clock;
            using duration_type = std::chrono::milliseconds;
 
            auto const start = clock_type::now();
            timed();
            auto const duration =
                std::chrono::duration_cast<duration_type>(clock_type::now() - start);
 
            log << label << " took " << duration.count() << "ms" << std::endl;
 
            return duration;
        };
 
        lifecycle(
            caseLabel,
            "timing",
            env,
            loanAmount,
            interestExponent,
            lender,
            borrower,
            evan,
            broker,
            pseudoAcct,
            tfLoanOverpayment,
            [&](Keylet const& loanKeylet, VerifyLoanStatus const& verifyLoanStatus) {
                // Estimate optimal values for kLoanPaymentsPerFeeIncrement and
                // kLoanMaximumPaymentsPerTransaction.
                using namespace loan;
 
                auto const state = getCurrentState(env, broker, verifyLoanStatus.keylet);
                auto const serviceFee = broker.asset(2).value();
 
                STAmount const totalDue{
                    broker.asset,
                    roundPeriodicPayment(
                        broker.asset, state.periodicPayment + serviceFee, state.loanScale)};
 
                // Make a single payment
                time("single payment", [&]() { env(pay(borrower, loanKeylet.key, totalDue)); });
                env.close();
 
                // Make all but the final payment
                auto const numPayments = (state.paymentRemaining - 2);
                STAmount const bigPayment{broker.asset, totalDue * numPayments};
                XRPAmount const bigFee{baseFee * (numPayments / kLoanPaymentsPerFeeIncrement + 1)};
                time("ten payments", [&]() {
                    env(pay(borrower, loanKeylet.key, bigPayment), Fee(bigFee));
                });
                env.close();
 
                time("final payment", [&]() {
                    // Make the final payment
                    env(pay(borrower, loanKeylet.key, totalDue + STAmount{broker.asset, 1}));
                });
                env.close();
            });
 
        lifecycle(
            caseLabel,
            "Loan overpayment allowed - Explicit overpayment",
            env,
            loanAmount,
            interestExponent,
            lender,
            borrower,
            evan,
            broker,
            pseudoAcct,
            tfLoanOverpayment,
            [&](Keylet const& loanKeylet, VerifyLoanStatus const& verifyLoanStatus) { throw 0; });
 
        lifecycle(
            caseLabel,
            "Loan overpayment prohibited - Late payment",
            env,
            loanAmount,
            interestExponent,
            lender,
            borrower,
            evan,
            broker,
            pseudoAcct,
            tfLoanOverpayment,
            [&](Keylet const& loanKeylet, VerifyLoanStatus const& verifyLoanStatus) { throw 0; });
 
        lifecycle(
            caseLabel,
            "Loan overpayment allowed - Late payment",
            env,
            loanAmount,
            interestExponent,
            lender,
            borrower,
            evan,
            broker,
            pseudoAcct,
            tfLoanOverpayment,
            [&](Keylet const& loanKeylet, VerifyLoanStatus const& verifyLoanStatus) { throw 0; });
 
        lifecycle(
            caseLabel,
            "Loan overpayment allowed - Late payment and overpayment",
            env,
            loanAmount,
            interestExponent,
            lender,
            borrower,
            evan,
            broker,
            pseudoAcct,
            tfLoanOverpayment,
            [&](Keylet const& loanKeylet, VerifyLoanStatus const& verifyLoanStatus) { throw 0; });
 
#endif
    }
};
 
}  // namespace xrpl::test