FixNFTokenPageLinks_test.cpp

 
#include <test/jtx/Account.h>
#include <test/jtx/Env.h>
#include <test/jtx/TestHelpers.h>
#include <test/jtx/amount.h>
#include <test/jtx/fee.h>
#include <test/jtx/ledgerStateFix.h>
#include <test/jtx/noop.h>
#include <test/jtx/ter.h>
#include <test/jtx/ticket.h>
#include <test/jtx/token.h>
#include <test/jtx/txflags.h>
 
#include <xrpl/basics/base_uint.h>
#include <xrpl/beast/unit_test/suite.h>
#include <xrpl/json/json_forwards.h>
#include <xrpl/json/json_value.h>
#include <xrpl/json/to_string.h>
#include <xrpl/protocol/Feature.h>
#include <xrpl/protocol/Indexes.h>
#include <xrpl/protocol/SField.h>
#include <xrpl/protocol/TER.h>
#include <xrpl/protocol/TxFlags.h>
#include <xrpl/protocol/jss.h>
#include <xrpl/protocol/nft.h>
 
#include <algorithm>
#include <cstdint>
#include <vector>
 
namespace xrpl {
 
class FixNFTokenPageLinks_test : public beast::unit_test::Suite
{
    // Helper function that returns the number of nfts owned by an account.
    static std::uint32_t
    nftCount(test::jtx::Env& env, test::jtx::Account const& acct)
    {
        json::Value params;
        params[jss::account] = acct.human();
        params[jss::type] = "state";
        json::Value nfts = env.rpc("json", "account_nfts", to_string(params));
        return nfts[jss::result][jss::account_nfts].size();
    };
 
    // A helper function that generates 96 nfts packed into three pages
    // of 32 each.  Returns a sorted vector of the NFTokenIDs packed into
    // the pages.
    std::vector<uint256>
    genPackedTokens(test::jtx::Env& env, test::jtx::Account const& owner)
    {
        using namespace test::jtx;
 
        std::vector<uint256> nfts;
        nfts.reserve(96);
 
        // We want to create fully packed NFT pages.  This is a little
        // tricky since the system currently in place is inclined to
        // assign consecutive tokens to only 16 entries per page.
        //
        // By manipulating the internal form of the taxon we can force
        // creation of NFT pages that are completely full.  This lambda
        // tells us the taxon value we should pass in in order for the
        // internal representation to match the passed in value.
        auto internalTaxon = [this, &env](
                                 Account const& acct, std::uint32_t taxon) -> std::uint32_t {
            std::uint32_t tokenSeq = [this, &env, &acct]() {
                auto const le = env.le(acct);
                if (BEAST_EXPECT(le))
                    return le->at(~sfMintedNFTokens).value_or(0u);
                return 0u;
            }();
 
            // We must add FirstNFTokenSequence.
            tokenSeq += env.le(acct)->at(~sfFirstNFTokenSequence).value_or(env.seq(acct));
 
            return toUInt32(nft::cipheredTaxon(tokenSeq, nft::toTaxon(taxon)));
        };
 
        for (std::uint32_t i = 0; i < 96; ++i)
        {
            // In order to fill the pages we use the taxon to break them
            // into groups of 16 entries.  By having the internal
            // representation of the taxon go...
            //   0, 3, 2, 5, 4, 7...
            // in sets of 16 NFTs we can get each page to be fully
            // populated.
            std::uint32_t const intTaxon = (i / 16) + (((i & 0b10000) != 0u) ? 2 : 0);
            uint32_t const extTaxon = internalTaxon(owner, intTaxon);
            nfts.push_back(token::getNextID(env, owner, extTaxon, tfTransferable));
            env(token::mint(owner, extTaxon), Txflags(tfTransferable));
            env.close();
        }
 
        // Sort the NFTs so they are listed in storage order, not
        // creation order.
        std::ranges::sort(nfts);
 
        // Verify that the owner does indeed have exactly three pages
        // of NFTs with 32 entries in each page.
        {
            json::Value params;
            params[jss::account] = owner.human();
            auto resp = env.rpc("json", "account_objects", to_string(params));
 
            json::Value const& acctObjs = resp[jss::result][jss::account_objects];
 
            int pageCount = 0;
            for (json::UInt i = 0; i < acctObjs.size(); ++i)
            {
                if (BEAST_EXPECT(
                        acctObjs[i].isMember(sfNFTokens.jsonName) &&
                        acctObjs[i][sfNFTokens.jsonName].isArray()))
                {
                    BEAST_EXPECT(acctObjs[i][sfNFTokens.jsonName].size() == 32);
                    ++pageCount;
                }
            }
            // If this check fails then the internal NFT directory logic
            // has changed.
            BEAST_EXPECT(pageCount == 3);
        }
        return nfts;
    };
 
    void
    testLedgerStateFixErrors()
    {
        testcase("LedgerStateFix error cases");
 
        using namespace test::jtx;
 
        Account const alice("alice");
 
        {
            // Verify that the LedgerStateFix transaction is disabled
            // without the fixNFTokenPageLinks amendment.
            Env env{*this, testableAmendments() - fixNFTokenPageLinks};
            env.fund(XRP(1000), alice);
 
            auto const linkFixFee = drops(env.current()->fees().increment);
            env(ledgerStateFix::nftPageLinks(alice, alice), Fee(linkFixFee), Ter(temDISABLED));
        }
 
        Env env{*this, testableAmendments()};
        env.fund(XRP(1000), alice);
        std::uint32_t const ticketSeq = env.seq(alice);
        env(ticket::create(alice, 1));
 
        // Preflight
 
        {
            // Fail preflight1.  Can't combine AccountTxnID and ticket.
            json::Value tx = ledgerStateFix::nftPageLinks(alice, alice);
            tx[sfAccountTxnID.jsonName] =
                "00000000000000000000000000000000"
                "00000000000000000000000000000000";
            env(tx, ticket::Use(ticketSeq), Ter(temINVALID));
        }
        // Fee too low.
        env(ledgerStateFix::nftPageLinks(alice, alice), Ter(telINSUF_FEE_P));
 
        // Invalid flags.
        auto const linkFixFee = drops(env.current()->fees().increment);
        env(ledgerStateFix::nftPageLinks(alice, alice),
            Fee(linkFixFee),
            Txflags(tfPassive),
            Ter(temINVALID_FLAG));
 
        {
            // ledgerStateFix::nftPageLinks requires an Owner field.
            json::Value tx = ledgerStateFix::nftPageLinks(alice, alice);
            tx.removeMember(sfOwner.jsonName);
            env(tx, Fee(linkFixFee), Ter(temINVALID));
        }
        {
            // NFTokenPageLink fixes require sfOwner and reject fields that
            // belong to other LedgerStateFix types.
            json::Value tx = ledgerStateFix::nftPageLinks(alice, alice);
            tx[sfBookDirectory.jsonName] = to_string(uint256{1});
            env(tx, Fee(linkFixFee), Ter(temINVALID));
        }
        {
            // Invalid LedgerFixType codes.
            json::Value tx = ledgerStateFix::nftPageLinks(alice, alice);
            tx[sfLedgerFixType.jsonName] = 0;
            env(tx, Fee(linkFixFee), Ter(tefINVALID_LEDGER_FIX_TYPE));
 
            tx[sfLedgerFixType.jsonName] = 200;
            env(tx, Fee(linkFixFee), Ter(tefINVALID_LEDGER_FIX_TYPE));
        }
 
        // Preclaim
        Account const carol("carol");
        env.memoize(carol);
        env(ledgerStateFix::nftPageLinks(alice, carol), Fee(linkFixFee), Ter(tecOBJECT_NOT_FOUND));
    }
 
    void
    testTokenPageLinkErrors()
    {
        testcase("NFTokenPageLinkFix error cases");
 
        using namespace test::jtx;
 
        Account const alice("alice");
 
        Env env{*this, testableAmendments()};
        env.fund(XRP(1000), alice);
 
        // These cases all return the same TER code, but they exercise
        // different cases where there is nothing to fix in an owner's
        // NFToken pages.  So they increase test coverage.
 
        // Owner has no pages to fix.
        auto const linkFixFee = drops(env.current()->fees().increment);
        env(ledgerStateFix::nftPageLinks(alice, alice), Fee(linkFixFee), Ter(tecFAILED_PROCESSING));
 
        // Alice has only one page.
        env(token::mint(alice), Txflags(tfTransferable));
        env.close();
 
        env(ledgerStateFix::nftPageLinks(alice, alice), Fee(linkFixFee), Ter(tecFAILED_PROCESSING));
 
        // Alice has at least three pages.
        for (std::uint32_t i = 0; i < 64; ++i)
        {
            env(token::mint(alice), Txflags(tfTransferable));
            env.close();
        }
 
        env(ledgerStateFix::nftPageLinks(alice, alice), Fee(linkFixFee), Ter(tecFAILED_PROCESSING));
    }
 
    void
    testFixNFTokenPageLinks()
    {
        // Steps:
        // 1. Before the fixNFTokenPageLinks amendment is enabled, build the
        //    three kinds of damaged NFToken directories we know about:
        //     A. One where there is only one page, but without the final index.
        //     B. One with multiple pages and a missing final page.
        //     C. One with links missing in the middle of the chain.
        // 2. Enable the fixNFTokenPageLinks amendment.
        // 3. Invoke the LedgerStateFix transactor and repair the directories.
        testcase("Fix links");
 
        using namespace test::jtx;
 
        Account const alice("alice");
        Account const bob("bob");
        Account const carol("carol");
        Account const daria("daria");
 
        Env env{*this, testableAmendments() - fixNFTokenPageLinks};
        env.fund(XRP(1000), alice, bob, carol, daria);
 
        //**********************************************************************
        // Step 1A: Create damaged NFToken directories:
        //   o One where there is only one page, but without the final index.
        //**********************************************************************
 
        // alice generates three packed pages.
        std::vector<uint256> aliceNFTs = genPackedTokens(env, alice);
        BEAST_EXPECT(nftCount(env, alice) == 96);
        BEAST_EXPECT(ownerCount(env, alice) == 3);
 
        // Get the index of the middle page.
        uint256 const aliceMiddleNFTokenPageIndex = [&env, &alice]() {
            auto lastNFTokenPage = env.le(keylet::nftokenPageMax(alice));
            return lastNFTokenPage->at(sfPreviousPageMin);
        }();
 
        // alice burns all the tokens in the first and last pages.
        for (int i = 0; i < 32; ++i)
        {
            env(token::burn(alice, {aliceNFTs[i]}));
            env.close();
        }
        aliceNFTs.erase(aliceNFTs.begin(), aliceNFTs.begin() + 32);
        for (int i = 0; i < 32; ++i)
        {
            env(token::burn(alice, {aliceNFTs.back()}));
            aliceNFTs.pop_back();
            env.close();
        }
        BEAST_EXPECT(ownerCount(env, alice) == 1);
        BEAST_EXPECT(nftCount(env, alice) == 32);
 
        // Removing the last token from the last page deletes the last
        // page.  This is a bug.  The contents of the next-to-last page
        // should have been moved into the last page.
        BEAST_EXPECT(!env.le(keylet::nftokenPageMax(alice)));
 
        // alice's "middle" page is still present, but has no links.
        {
            auto aliceMiddleNFTokenPage = env.le(
                keylet::nftokenPage(keylet::nftokenPageMin(alice), aliceMiddleNFTokenPageIndex));
            if (!BEAST_EXPECT(aliceMiddleNFTokenPage))
                return;
 
            BEAST_EXPECT(!aliceMiddleNFTokenPage->isFieldPresent(sfPreviousPageMin));
            BEAST_EXPECT(!aliceMiddleNFTokenPage->isFieldPresent(sfNextPageMin));
        }
 
        //**********************************************************************
        // Step 1B: Create damaged NFToken directories:
        //   o One with multiple pages and a missing final page.
        //**********************************************************************
 
        // bob generates three packed pages.
        std::vector<uint256> bobNFTs = genPackedTokens(env, bob);
        BEAST_EXPECT(nftCount(env, bob) == 96);
        BEAST_EXPECT(ownerCount(env, bob) == 3);
 
        // Get the index of the middle page.
        uint256 const bobMiddleNFTokenPageIndex = [&env, &bob]() {
            auto lastNFTokenPage = env.le(keylet::nftokenPageMax(bob));
            return lastNFTokenPage->at(sfPreviousPageMin);
        }();
 
        // bob burns all the tokens in the very last page.
        for (int i = 0; i < 32; ++i)
        {
            env(token::burn(bob, {bobNFTs.back()}));
            bobNFTs.pop_back();
            env.close();
        }
        BEAST_EXPECT(nftCount(env, bob) == 64);
        BEAST_EXPECT(ownerCount(env, bob) == 2);
 
        // Removing the last token from the last page deletes the last
        // page.  This is a bug.  The contents of the next-to-last page
        // should have been moved into the last page.
        BEAST_EXPECT(!env.le(keylet::nftokenPageMax(bob)));
 
        // bob's "middle" page is still present, but has lost the
        // NextPageMin field.
        {
            auto bobMiddleNFTokenPage =
                env.le(keylet::nftokenPage(keylet::nftokenPageMin(bob), bobMiddleNFTokenPageIndex));
            if (!BEAST_EXPECT(bobMiddleNFTokenPage))
                return;
 
            BEAST_EXPECT(bobMiddleNFTokenPage->isFieldPresent(sfPreviousPageMin));
            BEAST_EXPECT(!bobMiddleNFTokenPage->isFieldPresent(sfNextPageMin));
        }
 
        //**********************************************************************
        // Step 1C: Create damaged NFToken directories:
        //   o One with links missing in the middle of the chain.
        //**********************************************************************
 
        // carol generates three packed pages.
        std::vector<uint256> carolNFTs = genPackedTokens(env, carol);
        BEAST_EXPECT(nftCount(env, carol) == 96);
        BEAST_EXPECT(ownerCount(env, carol) == 3);
 
        // Get the index of the middle page.
        uint256 const carolMiddleNFTokenPageIndex = [&env, &carol]() {
            auto lastNFTokenPage = env.le(keylet::nftokenPageMax(carol));
            return lastNFTokenPage->at(sfPreviousPageMin);
        }();
 
        // carol sells all of the tokens in the very last page to daria.
        std::vector<uint256> dariaNFTs;
        dariaNFTs.reserve(32);
        for (int i = 0; i < 32; ++i)
        {
            uint256 const offerIndex = keylet::nftokenOffer(carol, env.seq(carol)).key;
            env(token::createOffer(carol, carolNFTs.back(), XRP(0)), Txflags(tfSellNFToken));
            env.close();
 
            env(token::acceptSellOffer(daria, offerIndex));
            env.close();
 
            dariaNFTs.push_back(carolNFTs.back());
            carolNFTs.pop_back();
        }
        BEAST_EXPECT(nftCount(env, carol) == 64);
        BEAST_EXPECT(ownerCount(env, carol) == 2);
 
        // Removing the last token from the last page deletes the last
        // page.  This is a bug.  The contents of the next-to-last page
        // should have been moved into the last page.
        BEAST_EXPECT(!env.le(keylet::nftokenPageMax(carol)));
 
        // carol's "middle" page is still present, but has lost the
        // NextPageMin field.
        auto carolMiddleNFTokenPage =
            env.le(keylet::nftokenPage(keylet::nftokenPageMin(carol), carolMiddleNFTokenPageIndex));
        if (!BEAST_EXPECT(carolMiddleNFTokenPage))
            return;
 
        BEAST_EXPECT(carolMiddleNFTokenPage->isFieldPresent(sfPreviousPageMin));
        BEAST_EXPECT(!carolMiddleNFTokenPage->isFieldPresent(sfNextPageMin));
 
        // At this point carol's NFT directory has the same problem that
        // bob's has: the last page is missing.  Now we make things more
        // complicated by putting the last page back.  carol buys their NFTs
        // back from daria.
        for (uint256 const& nft : dariaNFTs)
        {
            uint256 const offerIndex = keylet::nftokenOffer(carol, env.seq(carol)).key;
            env(token::createOffer(carol, nft, drops(1)), token::Owner(daria));
            env.close();
 
            env(token::acceptBuyOffer(daria, offerIndex));
            env.close();
 
            carolNFTs.push_back(nft);
        }
 
        // Note that carol actually owns 96 NFTs, but only 64 are reported
        // because the links are damaged.
        BEAST_EXPECT(nftCount(env, carol) == 64);
        BEAST_EXPECT(ownerCount(env, carol) == 3);
 
        // carol's "middle" page is present and still has no NextPageMin field.
        {
            auto carolMiddleNFTokenPage = env.le(
                keylet::nftokenPage(keylet::nftokenPageMin(carol), carolMiddleNFTokenPageIndex));
            if (!BEAST_EXPECT(carolMiddleNFTokenPage))
                return;
 
            BEAST_EXPECT(carolMiddleNFTokenPage->isFieldPresent(sfPreviousPageMin));
            BEAST_EXPECT(!carolMiddleNFTokenPage->isFieldPresent(sfNextPageMin));
        }
        // carol has a "last" page again, but it has no PreviousPageMin field.
        {
            auto carolLastNFTokenPage = env.le(keylet::nftokenPageMax(carol));
 
            BEAST_EXPECT(!carolLastNFTokenPage->isFieldPresent(sfPreviousPageMin));
            BEAST_EXPECT(!carolLastNFTokenPage->isFieldPresent(sfNextPageMin));
        }
 
        //**********************************************************************
        // Step 2: Enable the fixNFTokenPageLinks amendment.
        //**********************************************************************
        // Verify that the LedgerStateFix transaction is not enabled.
        auto const linkFixFee = drops(env.current()->fees().increment);
        env(ledgerStateFix::nftPageLinks(daria, alice), Fee(linkFixFee), Ter(temDISABLED));
 
        // Wait 15 ledgers so the LedgerStateFix transaction is no longer
        // retried.
        for (int i = 0; i < 15; ++i)
            env.close();
 
        env.enableFeature(fixNFTokenPageLinks);
        env.close();
 
        //**********************************************************************
        // Step 3A: Repair the one-page directory (alice's)
        //**********************************************************************
 
        // Verify that alice's NFToken directory is still damaged.
 
        // alice's last page should still be missing.
        BEAST_EXPECT(!env.le(keylet::nftokenPageMax(alice)));
 
        // alice's "middle" page is still present and has no links.
        {
            auto aliceMiddleNFTokenPage = env.le(
                keylet::nftokenPage(keylet::nftokenPageMin(alice), aliceMiddleNFTokenPageIndex));
            if (!BEAST_EXPECT(aliceMiddleNFTokenPage))
                return;
 
            BEAST_EXPECT(!aliceMiddleNFTokenPage->isFieldPresent(sfPreviousPageMin));
            BEAST_EXPECT(!aliceMiddleNFTokenPage->isFieldPresent(sfNextPageMin));
        }
 
        // The server "remembers" daria's failed nftPageLinks transaction
        // signature.  So we need to advance daria's sequence number before
        // daria can submit a similar transaction.
        env(noop(daria));
 
        // daria fixes the links in alice's NFToken directory.
        env(ledgerStateFix::nftPageLinks(daria, alice), Fee(linkFixFee));
        env.close();
 
        // alice's last page should now be present and include no links.
        {
            auto aliceLastNFTokenPage = env.le(keylet::nftokenPageMax(alice));
            if (!BEAST_EXPECT(aliceLastNFTokenPage))
                return;
 
            BEAST_EXPECT(!aliceLastNFTokenPage->isFieldPresent(sfPreviousPageMin));
            BEAST_EXPECT(!aliceLastNFTokenPage->isFieldPresent(sfNextPageMin));
        }
 
        // alice's middle page should be gone.
        BEAST_EXPECT(!env.le(
            keylet::nftokenPage(keylet::nftokenPageMin(alice), aliceMiddleNFTokenPageIndex)));
 
        BEAST_EXPECT(nftCount(env, alice) == 32);
        BEAST_EXPECT(ownerCount(env, alice) == 1);
 
        //**********************************************************************
        // Step 3B: Repair the two-page directory (bob's)
        //**********************************************************************
 
        // Verify that bob's NFToken directory is still damaged.
 
        // bob's last page should still be missing.
        BEAST_EXPECT(!env.le(keylet::nftokenPageMax(bob)));
 
        // bob's "middle" page is still present and missing NextPageMin.
        {
            auto bobMiddleNFTokenPage =
                env.le(keylet::nftokenPage(keylet::nftokenPageMin(bob), bobMiddleNFTokenPageIndex));
            if (!BEAST_EXPECT(bobMiddleNFTokenPage))
                return;
 
            BEAST_EXPECT(bobMiddleNFTokenPage->isFieldPresent(sfPreviousPageMin));
            BEAST_EXPECT(!bobMiddleNFTokenPage->isFieldPresent(sfNextPageMin));
        }
 
        // daria fixes the links in bob's NFToken directory.
        env(ledgerStateFix::nftPageLinks(daria, bob), Fee(linkFixFee));
        env.close();
 
        // bob's last page should now be present and include a previous
        // link but no next link.
        {
            auto const lastPageKeylet = keylet::nftokenPageMax(bob);
            auto const bobLastNFTokenPage = env.le(lastPageKeylet);
            if (!BEAST_EXPECT(bobLastNFTokenPage))
                return;
 
            BEAST_EXPECT(bobLastNFTokenPage->isFieldPresent(sfPreviousPageMin));
            BEAST_EXPECT(bobLastNFTokenPage->at(sfPreviousPageMin) != bobMiddleNFTokenPageIndex);
            BEAST_EXPECT(!bobLastNFTokenPage->isFieldPresent(sfNextPageMin));
 
            auto const bobNewFirstNFTokenPage = env.le(
                keylet::nftokenPage(
                    keylet::nftokenPageMin(bob), bobLastNFTokenPage->at(sfPreviousPageMin)));
            if (!BEAST_EXPECT(bobNewFirstNFTokenPage))
                return;
 
            BEAST_EXPECT(
                bobNewFirstNFTokenPage->isFieldPresent(sfNextPageMin) &&
                bobNewFirstNFTokenPage->at(sfNextPageMin) == lastPageKeylet.key);
            BEAST_EXPECT(!bobNewFirstNFTokenPage->isFieldPresent(sfPreviousPageMin));
        }
 
        // bob's middle page should be gone.
        BEAST_EXPECT(
            !env.le(keylet::nftokenPage(keylet::nftokenPageMin(bob), bobMiddleNFTokenPageIndex)));
 
        BEAST_EXPECT(nftCount(env, bob) == 64);
        BEAST_EXPECT(ownerCount(env, bob) == 2);
 
        //**********************************************************************
        // Step 3C: Repair the three-page directory (carol's)
        //**********************************************************************
 
        // Verify that carol's NFToken directory is still damaged.
 
        // carol's "middle" page is present and has no NextPageMin field.
        {
            auto carolMiddleNFTokenPage = env.le(
                keylet::nftokenPage(keylet::nftokenPageMin(carol), carolMiddleNFTokenPageIndex));
            if (!BEAST_EXPECT(carolMiddleNFTokenPage))
                return;
            BEAST_EXPECT(carolMiddleNFTokenPage->isFieldPresent(sfPreviousPageMin));
            BEAST_EXPECT(!carolMiddleNFTokenPage->isFieldPresent(sfNextPageMin));
        }
        // carol has a "last" page, but it has no PreviousPageMin field.
        {
            auto carolLastNFTokenPage = env.le(keylet::nftokenPageMax(carol));
 
            BEAST_EXPECT(!carolLastNFTokenPage->isFieldPresent(sfPreviousPageMin));
            BEAST_EXPECT(!carolLastNFTokenPage->isFieldPresent(sfNextPageMin));
        }
 
        // carol fixes the links in their own NFToken directory.
        env(ledgerStateFix::nftPageLinks(carol, carol), Fee(linkFixFee));
        env.close();
 
        {
            // carol's "middle" page is present and now has a NextPageMin field.
            auto const lastPageKeylet = keylet::nftokenPageMax(carol);
            auto carolMiddleNFTokenPage = env.le(
                keylet::nftokenPage(keylet::nftokenPageMin(carol), carolMiddleNFTokenPageIndex));
            if (!BEAST_EXPECT(carolMiddleNFTokenPage))
                return;
 
            BEAST_EXPECT(carolMiddleNFTokenPage->isFieldPresent(sfPreviousPageMin));
            BEAST_EXPECT(
                carolMiddleNFTokenPage->isFieldPresent(sfNextPageMin) &&
                carolMiddleNFTokenPage->at(sfNextPageMin) == lastPageKeylet.key);
 
            // carol has a "last" page that includes a PreviousPageMin field.
            auto carolLastNFTokenPage = env.le(lastPageKeylet);
            if (!BEAST_EXPECT(carolLastNFTokenPage))
                return;
 
            BEAST_EXPECT(
                carolLastNFTokenPage->isFieldPresent(sfPreviousPageMin) &&
                carolLastNFTokenPage->at(sfPreviousPageMin) == carolMiddleNFTokenPageIndex);
            BEAST_EXPECT(!carolLastNFTokenPage->isFieldPresent(sfNextPageMin));
 
            // carol also has a "first" page that includes a NextPageMin field.
            auto carolFirstNFTokenPage = env.le(
                keylet::nftokenPage(
                    keylet::nftokenPageMin(carol), carolMiddleNFTokenPage->at(sfPreviousPageMin)));
            if (!BEAST_EXPECT(carolFirstNFTokenPage))
                return;
 
            BEAST_EXPECT(
                carolFirstNFTokenPage->isFieldPresent(sfNextPageMin) &&
                carolFirstNFTokenPage->at(sfNextPageMin) == carolMiddleNFTokenPageIndex);
            BEAST_EXPECT(!carolFirstNFTokenPage->isFieldPresent(sfPreviousPageMin));
        }
 
        // With the link repair, the server knows that carol has 96 NFTs.
        BEAST_EXPECT(nftCount(env, carol) == 96);
        BEAST_EXPECT(ownerCount(env, carol) == 3);
    }
 
public:
    void
    run() override
    {
        testLedgerStateFixErrors();
        testTokenPageLinkErrors();
        testFixNFTokenPageLinks();
    }
};
 
BEAST_DEFINE_TESTSUITE(FixNFTokenPageLinks, app, xrpl);
 
}  // namespace xrpl