rippled/src/test/app/PayStrand_test.cpp

#include <test/jtx.h>
#include <test/jtx/PathSet.h>

#include <xrpld/app/paths/AMMContext.h>
#include <xrpld/app/paths/RippleCalc.h>
#include <xrpld/app/paths/detail/Steps.h>
#include <xrpld/core/Config.h>

#include <xrpl/basics/contract.h>
#include <xrpl/basics/safe_cast.h>
#include <xrpl/ledger/PaymentSandbox.h>
#include <xrpl/protocol/Feature.h>
#include <xrpl/protocol/jss.h>

#include <optional>

namespace xrpl {
namespace test {

struct DirectStepInfo
{
    AccountID src;
    AccountID dst;
    Currency currency;
};

struct XRPEndpointStepInfo
{
    AccountID acc;
};

enum class TrustFlag { freeze, auth, noripple };

/*constexpr*/ std::uint32_t
trustFlag(TrustFlag f, bool useHigh)
{
    switch (f)
    {
        case TrustFlag::freeze:
            if (useHigh)
                return lsfHighFreeze;
            return lsfLowFreeze;
        case TrustFlag::auth:
            if (useHigh)
                return lsfHighAuth;
            return lsfLowAuth;
        case TrustFlag::noripple:
            if (useHigh)
                return lsfHighNoRipple;
            return lsfLowNoRipple;
    }
    return 0;  // Silence warning about end of non-void function
}

bool
getTrustFlag(
    jtx::Env const& env,
    jtx::Account const& src,
    jtx::Account const& dst,
    Currency const& cur,
    TrustFlag flag)
{
    if (auto sle = env.le(keylet::line(src, dst, cur)))
    {
        auto const useHigh = src.id() > dst.id();
        return sle->isFlag(trustFlag(flag, useHigh));
    }
    Throw<std::runtime_error>("No line in getTrustFlag");
    return false;  // silence warning
}

bool
equal(std::unique_ptr<Step> const& s1, DirectStepInfo const& dsi)
{
    if (!s1)
        return false;
    return test::directStepEqual(*s1, dsi.src, dsi.dst, dsi.currency);
}

bool
equal(std::unique_ptr<Step> const& s1, XRPEndpointStepInfo const& xrpsi)
{
    if (!s1)
        return false;
    return test::xrpEndpointStepEqual(*s1, xrpsi.acc);
}

bool
equal(std::unique_ptr<Step> const& s1, xrpl::Book const& bsi)
{
    if (!s1)
        return false;
    return bookStepEqual(*s1, bsi);
}

template <class Iter>
bool
strandEqualHelper(Iter i)
{
    // base case. all args processed and found equal.
    return true;
}

template <class Iter, class StepInfo, class... Args>
bool
strandEqualHelper(Iter i, StepInfo&& si, Args&&... args)
{
    if (!equal(*i, std::forward<StepInfo>(si)))
        return false;
    return strandEqualHelper(++i, std::forward<Args>(args)...);
}

template <class... Args>
bool
equal(Strand const& strand, Args&&... args)
{
    if (strand.size() != sizeof...(Args))
        return false;
    if (strand.empty())
        return true;
    return strandEqualHelper(strand.begin(), std::forward<Args>(args)...);
}

STPathElement
ape(AccountID const& a)
{
    return STPathElement(
        STPathElement::typeAccount, a, xrpCurrency(), xrpAccount());
};

// Issue path element
STPathElement
ipe(Issue const& iss)
{
    return STPathElement(
        STPathElement::typeCurrency | STPathElement::typeIssuer,
        xrpAccount(),
        iss.currency,
        iss.account);
};

// Issuer path element
STPathElement
iape(AccountID const& account)
{
    return STPathElement(
        STPathElement::typeIssuer, xrpAccount(), xrpCurrency(), account);
};

class ElementComboIter
{
    enum class SB /*state bit*/
        : std::uint16_t {
            acc,
            iss,
            cur,
            rootAcc,
            rootIss,
            xrp,
            sameAccIss,
            existingAcc,
            existingCur,
            existingIss,
            prevAcc,
            prevCur,
            prevIss,
            boundary,
            last
        };

    std::uint16_t state_ = 0;
    static_assert(
        safe_cast<size_t>(SB::last) <= sizeof(decltype(state_)) * 8,
        "");
    STPathElement const* prev_ = nullptr;
    // disallow iss and cur to be specified with acc is specified (simplifies
    // some tests)
    bool const allowCompound_ = false;

    bool
    has(SB s) const
    {
        return state_ & (1 << safe_cast<int>(s));
    }

    bool
    hasAny(std::initializer_list<SB> sb) const
    {
        for (auto const s : sb)
            if (has(s))
                return true;
        return false;
    }

    size_t
    count(std::initializer_list<SB> sb) const
    {
        size_t result = 0;

        for (auto const s : sb)
            if (has(s))
                result++;
        return result;
    }

public:
    explicit ElementComboIter(STPathElement const* prev = nullptr) : prev_(prev)
    {
    }

    bool
    valid() const
    {
        return (allowCompound_ ||
                !(has(SB::acc) && hasAny({SB::cur, SB::iss}))) &&
            (!hasAny({SB::prevAcc, SB::prevCur, SB::prevIss}) || prev_) &&
            (!hasAny(
                 {SB::rootAcc, SB::sameAccIss, SB::existingAcc, SB::prevAcc}) ||
             has(SB::acc)) &&
            (!hasAny(
                 {SB::rootIss, SB::sameAccIss, SB::existingIss, SB::prevIss}) ||
             has(SB::iss)) &&
            (!hasAny({SB::xrp, SB::existingCur, SB::prevCur}) ||
             has(SB::cur)) &&
            // These will be duplicates
            (count({SB::xrp, SB::existingCur, SB::prevCur}) <= 1) &&
            (count({SB::rootAcc, SB::existingAcc, SB::prevAcc}) <= 1) &&
            (count({SB::rootIss, SB::existingIss, SB::rootIss}) <= 1);
    }
    bool
    next()
    {
        if (!(has(SB::last)))
        {
            do
            {
                ++state_;
            } while (!valid());
        }
        return !has(SB::last);
    }

    template <
        class Col,
        class AccFactory,
        class IssFactory,
        class CurrencyFactory>
    void
    emplace_into(
        Col& col,
        AccFactory&& accF,
        IssFactory&& issF,
        CurrencyFactory&& currencyF,
        std::optional<AccountID> const& existingAcc,
        std::optional<Currency> const& existingCur,
        std::optional<AccountID> const& existingIss)
    {
        assert(!has(SB::last));

        auto const acc = [&]() -> std::optional<AccountID> {
            if (!has(SB::acc))
                return std::nullopt;
            if (has(SB::rootAcc))
                return xrpAccount();
            if (has(SB::existingAcc) && existingAcc)
                return existingAcc;
            return accF().id();
        }();
        auto const iss = [&]() -> std::optional<AccountID> {
            if (!has(SB::iss))
                return std::nullopt;
            if (has(SB::rootIss))
                return xrpAccount();
            if (has(SB::sameAccIss))
                return acc;
            if (has(SB::existingIss) && existingIss)
                return *existingIss;
            return issF().id();
        }();
        auto const cur = [&]() -> std::optional<Currency> {
            if (!has(SB::cur))
                return std::nullopt;
            if (has(SB::xrp))
                return xrpCurrency();
            if (has(SB::existingCur) && existingCur)
                return *existingCur;
            return currencyF();
        }();
        if (!has(SB::boundary))
            col.emplace_back(acc, cur, iss);
        else
            col.emplace_back(
                STPathElement::Type::typeBoundary,
                acc.value_or(AccountID{}),
                cur.value_or(Currency{}),
                iss.value_or(AccountID{}));
    }
};

struct ExistingElementPool
{
    std::vector<jtx::Account> accounts;
    std::vector<xrpl::Currency> currencies;
    std::vector<std::string> currencyNames;

    jtx::Account
    getAccount(size_t id)
    {
        assert(id < accounts.size());
        return accounts[id];
    }

    xrpl::Currency
    getCurrency(size_t id)
    {
        assert(id < currencies.size());
        return currencies[id];
    }

    // ids from 0 through (nextAvail -1) have already been used in the
    // path
    size_t nextAvailAccount = 0;
    size_t nextAvailCurrency = 0;

    using ResetState = std::tuple<size_t, size_t>;
    ResetState
    getResetState() const
    {
        return std::make_tuple(nextAvailAccount, nextAvailCurrency);
    }

    void
    resetTo(ResetState const& s)
    {
        std::tie(nextAvailAccount, nextAvailCurrency) = s;
    }

    struct StateGuard
    {
        ExistingElementPool& p_;
        ResetState state_;

        explicit StateGuard(ExistingElementPool& p)
            : p_{p}, state_{p.getResetState()}
        {
        }
        ~StateGuard()
        {
            p_.resetTo(state_);
        }
    };

    // Create the given number of accounts, and add trust lines so every
    // account trusts every other with every currency
    // Create an offer from every currency/account to every other
    // currency/account; the offer owner is either the specified
    // account or the issuer of the "taker gets" account
    void
    setupEnv(
        jtx::Env& env,
        size_t numAct,
        size_t numCur,
        std::optional<size_t> const& offererIndex)
    {
        using namespace jtx;

        assert(!offererIndex || offererIndex < numAct);

        accounts.clear();
        accounts.reserve(numAct);
        currencies.clear();
        currencies.reserve(numCur);
        currencyNames.clear();
        currencyNames.reserve(numCur);

        constexpr size_t bufSize = 32;
        char buf[bufSize];

        for (size_t id = 0; id < numAct; ++id)
        {
            snprintf(buf, bufSize, "A%zu", id);
            accounts.emplace_back(buf);
        }

        for (size_t id = 0; id < numCur; ++id)
        {
            if (id < 10)
                snprintf(buf, bufSize, "CC%zu", id);
            else if (id < 100)
                snprintf(buf, bufSize, "C%zu", id);
            else
                snprintf(buf, bufSize, "%zu", id);
            currencies.emplace_back(to_currency(buf));
            currencyNames.emplace_back(buf);
        }

        for (auto const& a : accounts)
            env.fund(XRP(100000), a);

        // Every account trusts every other account with every currency
        for (auto ai1 = accounts.begin(), aie = accounts.end(); ai1 != aie;
             ++ai1)
        {
            for (auto ai2 = accounts.begin(); ai2 != aie; ++ai2)
            {
                if (ai1 == ai2)
                    continue;
                for (auto const& cn : currencyNames)
                {
                    env.trust((*ai1)[cn](1'000'000), *ai2);
                    if (ai1 > ai2)
                    {
                        // accounts with lower indexes hold balances from
                        // accounts
                        // with higher indexes
                        auto const& src = *ai1;
                        auto const& dst = *ai2;
                        env(pay(src, dst, src[cn](500000)));
                    }
                }
                env.close();
            }
        }

        std::vector<IOU> ious;
        ious.reserve(numAct * numCur);
        for (auto const& a : accounts)
            for (auto const& cn : currencyNames)
                ious.emplace_back(a[cn]);

        // create offers from every currency to every other currency
        for (auto takerPays = ious.begin(), ie = ious.end(); takerPays != ie;
             ++takerPays)
        {
            for (auto takerGets = ious.begin(); takerGets != ie; ++takerGets)
            {
                if (takerPays == takerGets)
                    continue;
                auto const owner =
                    offererIndex ? accounts[*offererIndex] : takerGets->account;
                if (owner.id() != takerGets->account.id())
                    env(pay(takerGets->account, owner, (*takerGets)(1000)));

                env(offer(owner, (*takerPays)(1000), (*takerGets)(1000)),
                    txflags(tfPassive));
            }
            env.close();
        }

        // create offers to/from xrp to every other ious
        for (auto const& iou : ious)
        {
            auto const owner =
                offererIndex ? accounts[*offererIndex] : iou.account;
            env(offer(owner, iou(1000), XRP(1000)), txflags(tfPassive));
            env(offer(owner, XRP(1000), iou(1000)), txflags(tfPassive));
            env.close();
        }
    }

    std::int64_t
    totalXRP(ReadView const& v, bool incRoot)
    {
        std::uint64_t totalXRP = 0;
        auto add = [&](auto const& a) {
            // XRP balance
            auto const sle = v.read(keylet::account(a));
            if (!sle)
                return;
            auto const b = (*sle)[sfBalance];
            totalXRP += b.mantissa();
        };
        for (auto const& a : accounts)
            add(a);
        if (incRoot)
            add(xrpAccount());
        return totalXRP;
    }

    // Check that the balances for all accounts for all currencies & XRP are the
    // same
    bool
    checkBalances(ReadView const& v1, ReadView const& v2)
    {
        std::vector<std::tuple<STAmount, STAmount, AccountID, AccountID>> diffs;

        auto xrpBalance = [](ReadView const& v, xrpl::Keylet const& k) {
            auto const sle = v.read(k);
            if (!sle)
                return STAmount{};
            return (*sle)[sfBalance];
        };
        auto lineBalance = [](ReadView const& v, xrpl::Keylet const& k) {
            auto const sle = v.read(k);
            if (!sle)
                return STAmount{};
            return (*sle)[sfBalance];
        };
        std::uint64_t totalXRP[2]{};
        for (auto ai1 = accounts.begin(), aie = accounts.end(); ai1 != aie;
             ++ai1)
        {
            {
                // XRP balance
                auto const ak = keylet::account(*ai1);
                auto const b1 = xrpBalance(v1, ak);
                auto const b2 = xrpBalance(v2, ak);
                totalXRP[0] += b1.mantissa();
                totalXRP[1] += b2.mantissa();
                if (b1 != b2)
                    diffs.emplace_back(b1, b2, xrpAccount(), *ai1);
            }
            for (auto ai2 = accounts.begin(); ai2 != aie; ++ai2)
            {
                if (ai1 >= ai2)
                    continue;
                for (auto const& c : currencies)
                {
                    // Line balance
                    auto const lk = keylet::line(*ai1, *ai2, c);
                    auto const b1 = lineBalance(v1, lk);
                    auto const b2 = lineBalance(v2, lk);
                    if (b1 != b2)
                        diffs.emplace_back(b1, b2, *ai1, *ai2);
                }
            }
        }
        return diffs.empty();
    }

    jtx::Account
    getAvailAccount()
    {
        return getAccount(nextAvailAccount++);
    }

    xrpl::Currency
    getAvailCurrency()
    {
        return getCurrency(nextAvailCurrency++);
    }

    template <class F>
    void
    for_each_element_pair(
        STAmount const& sendMax,
        STAmount const& deliver,
        std::vector<STPathElement> const& prefix,
        std::vector<STPathElement> const& suffix,
        std::optional<AccountID> const& existingAcc,
        std::optional<Currency> const& existingCur,
        std::optional<AccountID> const& existingIss,
        F&& f)
    {
        auto accF = [&] { return this->getAvailAccount(); };
        auto issF = [&] { return this->getAvailAccount(); };
        auto currencyF = [&] { return this->getAvailCurrency(); };

        STPathElement const* prevOuter =
            prefix.empty() ? nullptr : &prefix.back();
        ElementComboIter outer(prevOuter);

        std::vector<STPathElement> outerResult;
        std::vector<STPathElement> result;
        auto const resultSize = prefix.size() + suffix.size() + 2;
        outerResult.reserve(resultSize);
        result.reserve(resultSize);
        while (outer.next())
        {
            StateGuard og{*this};
            outerResult = prefix;
            outer.emplace_into(
                outerResult,
                accF,
                issF,
                currencyF,
                existingAcc,
                existingCur,
                existingIss);
            STPathElement const* prevInner = &outerResult.back();
            ElementComboIter inner(prevInner);
            while (inner.next())
            {
                StateGuard ig{*this};
                result = outerResult;
                inner.emplace_into(
                    result,
                    accF,
                    issF,
                    currencyF,
                    existingAcc,
                    existingCur,
                    existingIss);
                result.insert(result.end(), suffix.begin(), suffix.end());
                f(sendMax, deliver, result);
            }
        };
    }
};

struct PayStrand_test : public beast::unit_test::suite
{
    void
    testToStrand(FeatureBitset features)
    {
        testcase("To Strand");

        using namespace jtx;

        auto const alice = Account("alice");
        auto const bob = Account("bob");
        auto const carol = Account("carol");
        auto const gw = Account("gw");

        auto const USD = gw["USD"];
        auto const EUR = gw["EUR"];

        auto const eurC = EUR.currency;
        auto const usdC = USD.currency;

        using D = DirectStepInfo;
        using B = xrpl::Book;
        using XRPS = XRPEndpointStepInfo;

        AMMContext ammContext(alice, false);

        auto test = [&, this](
                        jtx::Env& env,
                        Issue const& deliver,
                        std::optional<Issue> const& sendMaxIssue,
                        STPath const& path,
                        TER expTer,
                        auto&&... expSteps) {
            auto [ter, strand] = toStrand(
                *env.current(),
                alice,
                bob,
                deliver,
                std::nullopt,
                sendMaxIssue,
                path,
                true,
                OfferCrossing::no,
                ammContext,
                std::nullopt,
                env.app().logs().journal("Flow"));
            BEAST_EXPECT(ter == expTer);
            if (sizeof...(expSteps) != 0)
                BEAST_EXPECT(equal(
                    strand, std::forward<decltype(expSteps)>(expSteps)...));
        };

        {
            Env env(*this, features);
            env.fund(XRP(10000), alice, bob, gw);
            env.trust(USD(1000), alice, bob);
            env.trust(EUR(1000), alice, bob);
            env(pay(gw, alice, EUR(100)));

            {
                STPath const path =
                    STPath({ipe(bob["USD"]), cpe(EUR.currency)});
                auto [ter, _] = toStrand(
                    *env.current(),
                    alice,
                    alice,
                    /*deliver*/ xrpIssue(),
                    /*limitQuality*/ std::nullopt,
                    /*sendMaxIssue*/ EUR.issue(),
                    path,
                    true,
                    OfferCrossing::no,
                    ammContext,
                    std::nullopt,
                    env.app().logs().journal("Flow"));
                (void)_;
                BEAST_EXPECT(ter == tesSUCCESS);
            }
            {
                STPath const path = STPath({ipe(USD), cpe(xrpCurrency())});
                auto [ter, _] = toStrand(
                    *env.current(),
                    alice,
                    alice,
                    /*deliver*/ xrpIssue(),
                    /*limitQuality*/ std::nullopt,
                    /*sendMaxIssue*/ EUR.issue(),
                    path,
                    true,
                    OfferCrossing::no,
                    ammContext,
                    std::nullopt,
                    env.app().logs().journal("Flow"));
                (void)_;
                BEAST_EXPECT(ter == tesSUCCESS);
            }
        }

        {
            Env env(*this, features);
            env.fund(XRP(10000), alice, bob, carol, gw);

            test(env, USD, std::nullopt, STPath(), terNO_LINE);

            env.trust(USD(1000), alice, bob, carol);
            test(env, USD, std::nullopt, STPath(), tecPATH_DRY);

            env(pay(gw, alice, USD(100)));
            env(pay(gw, carol, USD(100)));

            // Insert implied account
            test(
                env,
                USD,
                std::nullopt,
                STPath(),
                tesSUCCESS,
                D{alice, gw, usdC},
                D{gw, bob, usdC});
            env.trust(EUR(1000), alice, bob);

            // Insert implied offer
            test(
                env,
                EUR,
                USD.issue(),
                STPath(),
                tesSUCCESS,
                D{alice, gw, usdC},
                B{USD, EUR, std::nullopt},
                D{gw, bob, eurC});

            // Path with explicit offer
            test(
                env,
                EUR,
                USD.issue(),
                STPath({ipe(EUR)}),
                tesSUCCESS,
                D{alice, gw, usdC},
                B{USD, EUR, std::nullopt},
                D{gw, bob, eurC});

            // Path with offer that changes issuer only
            env.trust(carol["USD"](1000), bob);
            test(
                env,
                carol["USD"],
                USD.issue(),
                STPath({iape(carol)}),
                tesSUCCESS,
                D{alice, gw, usdC},
                B{USD, carol["USD"], std::nullopt},
                D{carol, bob, usdC});

            // Path with XRP src currency
            test(
                env,
                USD,
                xrpIssue(),
                STPath({ipe(USD)}),
                tesSUCCESS,
                XRPS{alice},
                B{XRP, USD, std::nullopt},
                D{gw, bob, usdC});

            // Path with XRP dst currency.
            test(
                env,
                xrpIssue(),
                USD.issue(),
                STPath({STPathElement{
                    STPathElement::typeCurrency,
                    xrpAccount(),
                    xrpCurrency(),
                    xrpAccount()}}),
                tesSUCCESS,
                D{alice, gw, usdC},
                B{USD, XRP, std::nullopt},
                XRPS{bob});

            // Path with XRP cross currency bridged payment
            test(
                env,
                EUR,
                USD.issue(),
                STPath({cpe(xrpCurrency())}),
                tesSUCCESS,
                D{alice, gw, usdC},
                B{USD, XRP, std::nullopt},
                B{XRP, EUR, std::nullopt},
                D{gw, bob, eurC});

            // XRP -> XRP transaction can't include a path
            test(env, XRP, std::nullopt, STPath({ape(carol)}), temBAD_PATH);

            {
                // The root account can't be the src or dst
                auto flowJournal = env.app().logs().journal("Flow");
                {
                    // The root account can't be the dst
                    auto r = toStrand(
                        *env.current(),
                        alice,
                        xrpAccount(),
                        XRP,
                        std::nullopt,
                        USD.issue(),
                        STPath(),
                        true,
                        OfferCrossing::no,
                        ammContext,
                        std::nullopt,
                        flowJournal);
                    BEAST_EXPECT(r.first == temBAD_PATH);
                }
                {
                    // The root account can't be the src
                    auto r = toStrand(
                        *env.current(),
                        xrpAccount(),
                        alice,
                        XRP,
                        std::nullopt,
                        std::nullopt,
                        STPath(),
                        true,
                        OfferCrossing::no,
                        ammContext,
                        std::nullopt,
                        flowJournal);
                    BEAST_EXPECT(r.first == temBAD_PATH);
                }
                {
                    // The root account can't be the src.
                    auto r = toStrand(
                        *env.current(),
                        noAccount(),
                        bob,
                        USD,
                        std::nullopt,
                        std::nullopt,
                        STPath(),
                        true,
                        OfferCrossing::no,
                        ammContext,
                        std::nullopt,
                        flowJournal);
                    BEAST_EXPECT(r.first == temBAD_PATH);
                }
            }

            // Create an offer with the same in/out issue
            test(
                env,
                EUR,
                USD.issue(),
                STPath({ipe(USD), ipe(EUR)}),
                temBAD_PATH);

            // Path element with type zero
            test(
                env,
                USD,
                std::nullopt,
                STPath({STPathElement(
                    0, xrpAccount(), xrpCurrency(), xrpAccount())}),
                temBAD_PATH);

            // The same account can't appear more than once on a path
            // `gw` will be used from alice->carol and implied between carol
            // and bob
            test(
                env,
                USD,
                std::nullopt,
                STPath({ape(gw), ape(carol)}),
                temBAD_PATH_LOOP);

            // The same offer can't appear more than once on a path
            test(
                env,
                EUR,
                USD.issue(),
                STPath({ipe(EUR), ipe(USD), ipe(EUR)}),
                temBAD_PATH_LOOP);
        }

        {
            // cannot have more than one offer with the same output issue

            using namespace jtx;
            Env env(*this, features);

            env.fund(XRP(10000), alice, bob, carol, gw);
            env.trust(USD(10000), alice, bob, carol);
            env.trust(EUR(10000), alice, bob, carol);

            env(pay(gw, bob, USD(100)));
            env(pay(gw, bob, EUR(100)));

            env(offer(bob, XRP(100), USD(100)));
            env(offer(bob, USD(100), EUR(100)), txflags(tfPassive));
            env(offer(bob, EUR(100), USD(100)), txflags(tfPassive));

            // payment path: XRP -> XRP/USD -> USD/EUR -> EUR/USD
            env(pay(alice, carol, USD(100)),
                path(~USD, ~EUR, ~USD),
                sendmax(XRP(200)),
                txflags(tfNoRippleDirect),
                ter(temBAD_PATH_LOOP));
        }

        {
            Env env(*this, features);
            env.fund(XRP(10000), alice, bob, noripple(gw));
            env.trust(USD(1000), alice, bob);
            env(pay(gw, alice, USD(100)));
            test(env, USD, std::nullopt, STPath(), terNO_RIPPLE);
        }

        {
            // check global freeze
            Env env(*this, features);
            env.fund(XRP(10000), alice, bob, gw);
            env.trust(USD(1000), alice, bob);
            env(pay(gw, alice, USD(100)));

            // Account can still issue payments
            env(fset(alice, asfGlobalFreeze));
            test(env, USD, std::nullopt, STPath(), tesSUCCESS);
            env(fclear(alice, asfGlobalFreeze));
            test(env, USD, std::nullopt, STPath(), tesSUCCESS);

            // Account can not issue funds
            env(fset(gw, asfGlobalFreeze));
            test(env, USD, std::nullopt, STPath(), terNO_LINE);
            env(fclear(gw, asfGlobalFreeze));
            test(env, USD, std::nullopt, STPath(), tesSUCCESS);

            // Account can not receive funds
            env(fset(bob, asfGlobalFreeze));
            test(env, USD, std::nullopt, STPath(), terNO_LINE);
            env(fclear(bob, asfGlobalFreeze));
            test(env, USD, std::nullopt, STPath(), tesSUCCESS);
        }
        {
            // Freeze between gw and alice
            Env env(*this, features);
            env.fund(XRP(10000), alice, bob, gw);
            env.trust(USD(1000), alice, bob);
            env(pay(gw, alice, USD(100)));
            test(env, USD, std::nullopt, STPath(), tesSUCCESS);
            env(trust(gw, alice["USD"](0), tfSetFreeze));
            BEAST_EXPECT(getTrustFlag(env, gw, alice, usdC, TrustFlag::freeze));
            test(env, USD, std::nullopt, STPath(), terNO_LINE);
        }
        {
            // check no auth
            // An account may require authorization to receive IOUs from an
            // issuer
            Env env(*this, features);
            env.fund(XRP(10000), alice, bob, gw);
            env(fset(gw, asfRequireAuth));
            env.trust(USD(1000), alice, bob);
            // Authorize alice but not bob
            env(trust(gw, alice["USD"](1000), tfSetfAuth));
            BEAST_EXPECT(getTrustFlag(env, gw, alice, usdC, TrustFlag::auth));
            env(pay(gw, alice, USD(100)));
            env.require(balance(alice, USD(100)));
            test(env, USD, std::nullopt, STPath(), terNO_AUTH);

            // Check pure issue redeem still works
            auto [ter, strand] = toStrand(
                *env.current(),
                alice,
                gw,
                USD,
                std::nullopt,
                std::nullopt,
                STPath(),
                true,
                OfferCrossing::no,
                ammContext,
                std::nullopt,
                env.app().logs().journal("Flow"));
            BEAST_EXPECT(ter == tesSUCCESS);
            BEAST_EXPECT(equal(strand, D{alice, gw, usdC}));
        }

        {
            // last step xrp from offer
            Env env(*this, features);
            env.fund(XRP(10000), alice, bob, gw);
            env.trust(USD(1000), alice, bob);
            env(pay(gw, alice, USD(100)));

            // alice -> USD/XRP -> bob
            STPath path;
            path.emplace_back(std::nullopt, xrpCurrency(), std::nullopt);

            auto [ter, strand] = toStrand(
                *env.current(),
                alice,
                bob,
                XRP,
                std::nullopt,
                USD.issue(),
                path,
                false,
                OfferCrossing::no,
                ammContext,
                std::nullopt,
                env.app().logs().journal("Flow"));
            BEAST_EXPECT(ter == tesSUCCESS);
            BEAST_EXPECT(equal(
                strand,
                D{alice, gw, usdC},
                B{USD.issue(), xrpIssue(), std::nullopt},
                XRPS{bob}));
        }
    }

    void
    testRIPD1373(FeatureBitset features)
    {
        using namespace jtx;
        testcase("RIPD1373");

        auto const alice = Account("alice");
        auto const bob = Account("bob");
        auto const carol = Account("carol");
        auto const gw = Account("gw");
        auto const USD = gw["USD"];
        auto const EUR = gw["EUR"];

        {
            Env env(*this, features);
            env.fund(XRP(10000), alice, bob, gw);

            env.trust(USD(1000), alice, bob);
            env.trust(EUR(1000), alice, bob);
            env.trust(bob["USD"](1000), alice, gw);
            env.trust(bob["EUR"](1000), alice, gw);

            env(offer(bob, XRP(100), bob["USD"](100)), txflags(tfPassive));
            env(offer(gw, XRP(100), USD(100)), txflags(tfPassive));

            env(offer(bob, bob["USD"](100), bob["EUR"](100)),
                txflags(tfPassive));
            env(offer(gw, USD(100), EUR(100)), txflags(tfPassive));

            Path const p = [&] {
                Path result;
                result.push_back(allpe(gw, bob["USD"]));
                result.push_back(cpe(EUR.currency));
                return result;
            }();

            PathSet paths(p);

            env(pay(alice, alice, EUR(1)),
                json(paths.json()),
                sendmax(XRP(10)),
                txflags(tfNoRippleDirect | tfPartialPayment),
                ter(temBAD_PATH));
        }

        {
            Env env(*this, features);

            env.fund(XRP(10000), alice, bob, carol, gw);
            env.trust(USD(10000), alice, bob, carol);

            env(pay(gw, bob, USD(100)));

            env(offer(bob, XRP(100), USD(100)), txflags(tfPassive));
            env(offer(bob, USD(100), XRP(100)), txflags(tfPassive));

            // payment path: XRP -> XRP/USD -> USD/XRP
            env(pay(alice, carol, XRP(100)),
                path(~USD, ~XRP),
                txflags(tfNoRippleDirect),
                ter(temBAD_SEND_XRP_PATHS));
        }

        {
            Env env(*this, features);

            env.fund(XRP(10000), alice, bob, carol, gw);
            env.trust(USD(10000), alice, bob, carol);

            env(pay(gw, bob, USD(100)));

            env(offer(bob, XRP(100), USD(100)), txflags(tfPassive));
            env(offer(bob, USD(100), XRP(100)), txflags(tfPassive));

            // payment path: XRP -> XRP/USD -> USD/XRP
            env(pay(alice, carol, XRP(100)),
                path(~USD, ~XRP),
                sendmax(XRP(200)),
                txflags(tfNoRippleDirect),
                ter(temBAD_SEND_XRP_MAX));
        }
    }

    void
    testLoop(FeatureBitset features)
    {
        testcase("test loop");
        using namespace jtx;

        auto const alice = Account("alice");
        auto const bob = Account("bob");
        auto const carol = Account("carol");
        auto const gw = Account("gw");
        auto const USD = gw["USD"];
        auto const EUR = gw["EUR"];
        auto const CNY = gw["CNY"];

        {
            Env env(*this, features);

            env.fund(XRP(10000), alice, bob, carol, gw);
            env.trust(USD(10000), alice, bob, carol);

            env(pay(gw, bob, USD(100)));
            env(pay(gw, alice, USD(100)));

            env(offer(bob, XRP(100), USD(100)), txflags(tfPassive));
            env(offer(bob, USD(100), XRP(100)), txflags(tfPassive));

            // payment path: USD -> USD/XRP -> XRP/USD
            env(pay(alice, carol, USD(100)),
                sendmax(USD(100)),
                path(~XRP, ~USD),
                txflags(tfNoRippleDirect),
                ter(temBAD_PATH_LOOP));
        }
        {
            Env env(*this, features);

            env.fund(XRP(10000), alice, bob, carol, gw);
            env.trust(USD(10000), alice, bob, carol);
            env.trust(EUR(10000), alice, bob, carol);
            env.trust(CNY(10000), alice, bob, carol);

            env(pay(gw, bob, USD(100)));
            env(pay(gw, bob, EUR(100)));
            env(pay(gw, bob, CNY(100)));

            env(offer(bob, XRP(100), USD(100)), txflags(tfPassive));
            env(offer(bob, USD(100), EUR(100)), txflags(tfPassive));
            env(offer(bob, EUR(100), CNY(100)), txflags(tfPassive));

            // payment path: XRP->XRP/USD->USD/EUR->USD/CNY
            env(pay(alice, carol, CNY(100)),
                sendmax(XRP(100)),
                path(~USD, ~EUR, ~USD, ~CNY),
                txflags(tfNoRippleDirect),
                ter(temBAD_PATH_LOOP));
        }
    }

    void
    testNoAccount(FeatureBitset features)
    {
        testcase("test no account");
        using namespace jtx;

        auto const alice = Account("alice");
        auto const bob = Account("bob");
        auto const gw = Account("gw");
        auto const USD = gw["USD"];

        Env env(*this, features);
        env.fund(XRP(10000), alice, bob, gw);

        STAmount sendMax{USD.issue(), 100, 1};
        STAmount noAccountAmount{Issue{USD.currency, noAccount()}, 100, 1};
        STAmount deliver;
        AccountID const srcAcc = alice.id();
        AccountID dstAcc = bob.id();
        STPathSet pathSet;
        ::xrpl::path::RippleCalc::Input inputs;
        inputs.defaultPathsAllowed = true;
        try
        {
            PaymentSandbox sb{env.current().get(), tapNONE};
            {
                auto const r = ::xrpl::path::RippleCalc::rippleCalculate(
                    sb,
                    sendMax,
                    deliver,
                    dstAcc,
                    noAccount(),
                    pathSet,
                    std::nullopt,
                    env.app().logs(),
                    &inputs);
                BEAST_EXPECT(r.result() == temBAD_PATH);
            }
            {
                auto const r = ::xrpl::path::RippleCalc::rippleCalculate(
                    sb,
                    sendMax,
                    deliver,
                    noAccount(),
                    srcAcc,
                    pathSet,
                    std::nullopt,
                    env.app().logs(),
                    &inputs);
                BEAST_EXPECT(r.result() == temBAD_PATH);
            }
            {
                auto const r = ::xrpl::path::RippleCalc::rippleCalculate(
                    sb,
                    noAccountAmount,
                    deliver,
                    dstAcc,
                    srcAcc,
                    pathSet,
                    std::nullopt,
                    env.app().logs(),
                    &inputs);
                BEAST_EXPECT(r.result() == temBAD_PATH);
            }
            {
                auto const r = ::xrpl::path::RippleCalc::rippleCalculate(
                    sb,
                    sendMax,
                    noAccountAmount,
                    dstAcc,
                    srcAcc,
                    pathSet,
                    std::nullopt,
                    env.app().logs(),
                    &inputs);
                BEAST_EXPECT(r.result() == temBAD_PATH);
            }
        }
        catch (...)
        {
            this->fail();
        }
    }

    void
    run() override
    {
        using namespace jtx;
        auto const sa = testable_amendments();
        testToStrand(sa - featurePermissionedDEX);
        testToStrand(sa);

        testRIPD1373(sa - featurePermissionedDEX);
        testRIPD1373(sa);

        testLoop(sa - featurePermissionedDEX);
        testLoop(sa);

        testNoAccount(sa);
    }
};

BEAST_DEFINE_TESTSUITE(PayStrand, app, xrpl);

}  // namespace test
}  // namespace xrpl