rbf_tests.cpp

// Copyright (c) 2021-2022 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include <common/system.h>
#include <policy/rbf.h>
#include <random.h>
#include <test/util/txmempool.h>
#include <txmempool.h>
#include <util/time.h>

#include <test/util/setup_common.h>

#include <boost/test/unit_test.hpp>
#include <optional>
#include <vector>

BOOST_FIXTURE_TEST_SUITE(rbf_tests, TestingSetup)

static inline CTransactionRef make_tx(const std::vector<CTransactionRef>& inputs,
 const std::vector<CAmount>& output_values)
{
 CMutableTransaction tx = CMutableTransaction();
 tx.vin.resize(inputs.size());
 tx.vout.resize(output_values.size());
 for (size_t i = 0; i < inputs.size(); ++i) {
 tx.vin[i].prevout.hash = inputs[i]->GetHash();
 tx.vin[i].prevout.n = 0;
 // Add a witness so wtxid != txid
 CScriptWitness witness;
 witness.stack.emplace_back(i + 10);
 tx.vin[i].scriptWitness = witness;
 }
 for (size_t i = 0; i < output_values.size(); ++i) {
 tx.vout[i].scriptPubKey = CScript() << OP_11 << OP_EQUAL;
 tx.vout[i].nValue = output_values[i];
 }
 return MakeTransactionRef(tx);
}

// Make two child transactions from parent (which must have at least 2 outputs).
// Each tx will have the same outputs, using the amounts specified in output_values.
static inline std::pair<CTransactionRef, CTransactionRef> make_two_siblings(const CTransactionRef parent,
 const std::vector<CAmount>& output_values)
{
 assert(parent->vout.size() >= 2);

 // First tx takes first parent output
 CMutableTransaction tx1 = CMutableTransaction();
 tx1.vin.resize(1);
 tx1.vout.resize(output_values.size());

 tx1.vin[0].prevout.hash = parent->GetHash();
 tx1.vin[0].prevout.n = 0;
 // Add a witness so wtxid != txid
 CScriptWitness witness;
 witness.stack.emplace_back(10);
 tx1.vin[0].scriptWitness = witness;

 for (size_t i = 0; i < output_values.size(); ++i) {
 tx1.vout[i].scriptPubKey = CScript() << OP_11 << OP_EQUAL;
 tx1.vout[i].nValue = output_values[i];
 }

 // Second tx takes second parent output
 CMutableTransaction tx2 = tx1;
 tx2.vin[0].prevout.n = 1;

 return std::make_pair(MakeTransactionRef(tx1), MakeTransactionRef(tx2));
}

static CTransactionRef add_descendants(const CTransactionRef& tx, int32_t num_descendants, CTxMemPool& pool)
 EXCLUSIVE_LOCKS_REQUIRED(::cs_main, pool.cs)
{
 AssertLockHeld(::cs_main);
 AssertLockHeld(pool.cs);
 TestMemPoolEntryHelper entry;
 // Assumes this isn't already spent in mempool
 auto tx_to_spend = tx;
 for (int32_t i{0}; i < num_descendants; ++i) {
 auto next_tx = make_tx(/*inputs=*/{tx_to_spend}, /*output_values=*/{(50 - i) * CENT});
 AddToMempool(pool, entry.FromTx(next_tx));
 tx_to_spend = next_tx;
 }
 // Return last created tx
 return tx_to_spend;
}

static CTransactionRef add_descendant_to_parents(const std::vector<CTransactionRef>& parents, CTxMemPool& pool)
 EXCLUSIVE_LOCKS_REQUIRED(::cs_main, pool.cs)
{
 AssertLockHeld(::cs_main);
 AssertLockHeld(pool.cs);
 TestMemPoolEntryHelper entry;
 // Assumes this isn't already spent in mempool
 auto child_tx = make_tx(/*inputs=*/parents, /*output_values=*/{50 * CENT});
 AddToMempool(pool, entry.FromTx(child_tx));
 // Return last created tx
 return child_tx;
}

// Makes two children for a single parent
static std::pair<CTransactionRef, CTransactionRef> add_children_to_parent(const CTransactionRef parent, CTxMemPool& pool)
 EXCLUSIVE_LOCKS_REQUIRED(::cs_main, pool.cs)
{
 AssertLockHeld(::cs_main);
 AssertLockHeld(pool.cs);
 TestMemPoolEntryHelper entry;
 // Assumes this isn't already spent in mempool
 auto children_tx = make_two_siblings(/*parent=*/parent, /*output_values=*/{50 * CENT});
 AddToMempool(pool, entry.FromTx(children_tx.first));
 AddToMempool(pool, entry.FromTx(children_tx.second));
 return children_tx;
}

BOOST_FIXTURE_TEST_CASE(rbf_helper_functions, TestChain100Setup)
{
 CTxMemPool& pool = *Assert(m_node.mempool);
 LOCK2(::cs_main, pool.cs);
 TestMemPoolEntryHelper entry;

 const CAmount low_fee{CENT/100};
 const CAmount normal_fee{CENT/10};
 const CAmount high_fee{CENT};

 // Create a parent tx1 and child tx2 with normal fees:
 const auto tx1 = make_tx(/*inputs=*/ {m_coinbase_txns[0]}, /*output_values=*/ {10 * COIN});
 AddToMempool(pool, entry.Fee(normal_fee).FromTx(tx1));
 const auto tx2 = make_tx(/*inputs=*/ {tx1}, /*output_values=*/ {995 * CENT});
 AddToMempool(pool, entry.Fee(normal_fee).FromTx(tx2));

 // Create a low-feerate parent tx3 and high-feerate child tx4 (cpfp)
 const auto tx3 = make_tx(/*inputs=*/ {m_coinbase_txns[1]}, /*output_values=*/ {1099 * CENT});
 AddToMempool(pool, entry.Fee(low_fee).FromTx(tx3));
 const auto tx4 = make_tx(/*inputs=*/ {tx3}, /*output_values=*/ {999 * CENT});
 AddToMempool(pool, entry.Fee(high_fee).FromTx(tx4));

 // Create a parent tx5 and child tx6 where both have very low fees
 const auto tx5 = make_tx(/*inputs=*/ {m_coinbase_txns[2]}, /*output_values=*/ {1099 * CENT});
 AddToMempool(pool, entry.Fee(low_fee).FromTx(tx5));
 const auto tx6 = make_tx(/*inputs=*/ {tx5}, /*output_values=*/ {1098 * CENT});
 AddToMempool(pool, entry.Fee(low_fee).FromTx(tx6));
 // Make tx6's modified fee much higher than its base fee. This should cause it to pass
 // the fee-related checks despite being low-feerate.
 pool.PrioritiseTransaction(tx6->GetHash(), 1 * COIN);

 // Two independent high-feerate transactions, tx7 and tx8
 const auto tx7 = make_tx(/*inputs=*/ {m_coinbase_txns[3]}, /*output_values=*/ {999 * CENT});
 AddToMempool(pool, entry.Fee(high_fee).FromTx(tx7));
 const auto tx8 = make_tx(/*inputs=*/ {m_coinbase_txns[4]}, /*output_values=*/ {999 * CENT});
 AddToMempool(pool, entry.Fee(high_fee).FromTx(tx8));

 // Normal txs, will chain txns right before CheckConflictTopology test
 const auto tx9 = make_tx(/*inputs=*/ {m_coinbase_txns[5]}, /*output_values=*/ {995 * CENT});
 AddToMempool(pool, entry.Fee(normal_fee).FromTx(tx9));
 const auto tx10 = make_tx(/*inputs=*/ {m_coinbase_txns[6]}, /*output_values=*/ {995 * CENT});
 AddToMempool(pool, entry.Fee(normal_fee).FromTx(tx10));

 // Will make these two parents of single child
 const auto tx11 = make_tx(/*inputs=*/ {m_coinbase_txns[7]}, /*output_values=*/ {995 * CENT});
 AddToMempool(pool, entry.Fee(normal_fee).FromTx(tx11));
 const auto tx12 = make_tx(/*inputs=*/ {m_coinbase_txns[8]}, /*output_values=*/ {995 * CENT});
 AddToMempool(pool, entry.Fee(normal_fee).FromTx(tx12));

 // Will make two children of this single parent
 const auto tx13 = make_tx(/*inputs=*/ {m_coinbase_txns[9]}, /*output_values=*/ {995 * CENT, 995 * CENT});
 AddToMempool(pool, entry.Fee(normal_fee).FromTx(tx13));

 const auto entry1_normal = pool.GetIter(tx1->GetHash()).value();
 const auto entry2_normal = pool.GetIter(tx2->GetHash()).value();
 const auto entry3_low = pool.GetIter(tx3->GetHash()).value();
 const auto entry4_high = pool.GetIter(tx4->GetHash()).value();
 const auto entry5_low = pool.GetIter(tx5->GetHash()).value();
 const auto entry6_low_prioritised = pool.GetIter(tx6->GetHash()).value();
 const auto entry7_high = pool.GetIter(tx7->GetHash()).value();
 const auto entry8_high = pool.GetIter(tx8->GetHash()).value();
 const auto entry9_unchained = pool.GetIter(tx9->GetHash()).value();
 const auto entry10_unchained = pool.GetIter(tx10->GetHash()).value();
 const auto entry11_unchained = pool.GetIter(tx11->GetHash()).value();
 const auto entry12_unchained = pool.GetIter(tx12->GetHash()).value();
 const auto entry13_unchained = pool.GetIter(tx13->GetHash()).value();

 BOOST_CHECK_EQUAL(entry1_normal->GetFee(), normal_fee);
 BOOST_CHECK_EQUAL(entry2_normal->GetFee(), normal_fee);
 BOOST_CHECK_EQUAL(entry3_low->GetFee(), low_fee);
 BOOST_CHECK_EQUAL(entry4_high->GetFee(), high_fee);
 BOOST_CHECK_EQUAL(entry5_low->GetFee(), low_fee);
 BOOST_CHECK_EQUAL(entry6_low_prioritised->GetFee(), low_fee);
 BOOST_CHECK_EQUAL(entry7_high->GetFee(), high_fee);
 BOOST_CHECK_EQUAL(entry8_high->GetFee(), high_fee);

 CTxMemPool::setEntries set_12_normal{entry1_normal, entry2_normal};
 CTxMemPool::setEntries set_34_cpfp{entry3_low, entry4_high};
 CTxMemPool::setEntries set_56_low{entry5_low, entry6_low_prioritised};
 CTxMemPool::setEntries set_78_high{entry7_high, entry8_high};
 CTxMemPool::setEntries all_entries{entry1_normal, entry2_normal, entry3_low, entry4_high,
 entry5_low, entry6_low_prioritised, entry7_high, entry8_high};
 CTxMemPool::setEntries empty_set;

 const auto unused_txid{GetRandHash()};

 // Tests for PaysMoreThanConflicts
 // These tests use feerate, not absolute fee.
 BOOST_CHECK(PaysMoreThanConflicts(/*iters_conflicting=*/set_12_normal,
 /*replacement_feerate=*/CFeeRate(entry1_normal->GetModifiedFee() + 1, entry1_normal->GetTxSize() + 2),
 /*txid=*/unused_txid).has_value());
 // Replacement must be strictly greater than the originals.
 BOOST_CHECK(PaysMoreThanConflicts(set_12_normal, CFeeRate(entry1_normal->GetModifiedFee(), entry1_normal->GetTxSize()), unused_txid).has_value());
 BOOST_CHECK(PaysMoreThanConflicts(set_12_normal, CFeeRate(entry1_normal->GetModifiedFee() + 1, entry1_normal->GetTxSize()), unused_txid) == std::nullopt);
 // These tests use modified fees (including prioritisation), not base fees.
 BOOST_CHECK(PaysMoreThanConflicts({entry5_low}, CFeeRate(entry5_low->GetModifiedFee() + 1, entry5_low->GetTxSize()), unused_txid) == std::nullopt);
 BOOST_CHECK(PaysMoreThanConflicts({entry6_low_prioritised}, CFeeRate(entry6_low_prioritised->GetFee() + 1, entry6_low_prioritised->GetTxSize()), unused_txid).has_value());
 BOOST_CHECK(PaysMoreThanConflicts({entry6_low_prioritised}, CFeeRate(entry6_low_prioritised->GetModifiedFee() + 1, entry6_low_prioritised->GetTxSize()), unused_txid) == std::nullopt);
 // PaysMoreThanConflicts checks individual feerate, not ancestor feerate. This test compares
 // replacement_feerate and entry4_high's feerate, which are the same. The replacement_feerate is
 // considered too low even though entry4_high has a low ancestor feerate.
 BOOST_CHECK(PaysMoreThanConflicts(set_34_cpfp, CFeeRate(entry4_high->GetModifiedFee(), entry4_high->GetTxSize()), unused_txid).has_value());

 // Tests for EntriesAndTxidsDisjoint
 BOOST_CHECK(EntriesAndTxidsDisjoint(empty_set, {tx1->GetHash()}, unused_txid) == std::nullopt);
 BOOST_CHECK(EntriesAndTxidsDisjoint(set_12_normal, {tx3->GetHash()}, unused_txid) == std::nullopt);
 BOOST_CHECK(EntriesAndTxidsDisjoint({entry2_normal}, {tx2->GetHash()}, unused_txid).has_value());
 BOOST_CHECK(EntriesAndTxidsDisjoint(set_12_normal, {tx1->GetHash()}, unused_txid).has_value());
 BOOST_CHECK(EntriesAndTxidsDisjoint(set_12_normal, {tx2->GetHash()}, unused_txid).has_value());
 // EntriesAndTxidsDisjoint does not calculate descendants of iters_conflicting; it uses whatever
 // the caller passed in. As such, no error is returned even though entry2_normal is a descendant of tx1.
 BOOST_CHECK(EntriesAndTxidsDisjoint({entry2_normal}, {tx1->GetHash()}, unused_txid) == std::nullopt);

 // Tests for PaysForRBF
 const CFeeRate incremental_relay_feerate{DEFAULT_INCREMENTAL_RELAY_FEE};
 const CFeeRate higher_relay_feerate{2 * DEFAULT_INCREMENTAL_RELAY_FEE};
 // Must pay at least as much as the original.
 BOOST_CHECK(PaysForRBF(/*original_fees=*/high_fee,
 /*replacement_fees=*/high_fee,
 /*replacement_vsize=*/1,
 /*relay_fee=*/CFeeRate(0),
 /*txid=*/unused_txid)
 == std::nullopt);
 BOOST_CHECK(PaysForRBF(high_fee, high_fee - 1, 1, CFeeRate(0), unused_txid).has_value());
 BOOST_CHECK(PaysForRBF(high_fee + 1, high_fee, 1, CFeeRate(0), unused_txid).has_value());
 // Additional fees must cover the replacement's vsize at incremental relay fee
 BOOST_CHECK(PaysForRBF(high_fee, high_fee + 1, 2, incremental_relay_feerate, unused_txid).has_value());
 BOOST_CHECK(PaysForRBF(high_fee, high_fee + 2, 2, incremental_relay_feerate, unused_txid) == std::nullopt);
 BOOST_CHECK(PaysForRBF(high_fee, high_fee + 2, 2, higher_relay_feerate, unused_txid).has_value());
 BOOST_CHECK(PaysForRBF(high_fee, high_fee + 4, 2, higher_relay_feerate, unused_txid) == std::nullopt);
 BOOST_CHECK(PaysForRBF(low_fee, high_fee, 99999999, incremental_relay_feerate, unused_txid).has_value());
 BOOST_CHECK(PaysForRBF(low_fee, high_fee + 99999999, 99999999, incremental_relay_feerate, unused_txid) == std::nullopt);

 // Tests for GetEntriesForConflicts
 CTxMemPool::setEntries all_parents{entry1_normal, entry3_low, entry5_low, entry7_high, entry8_high};
 CTxMemPool::setEntries all_children{entry2_normal, entry4_high, entry6_low_prioritised};
 const std::vector<CTransactionRef> parent_inputs({m_coinbase_txns[0], m_coinbase_txns[1], m_coinbase_txns[2],
 m_coinbase_txns[3], m_coinbase_txns[4]});
 const auto conflicts_with_parents = make_tx(parent_inputs, {50 * CENT});
 CTxMemPool::setEntries all_conflicts;
 BOOST_CHECK(GetEntriesForConflicts(/*tx=*/ *conflicts_with_parents.get(),
 /*pool=*/ pool,
 /*iters_conflicting=*/ all_parents,
 /*all_conflicts=*/ all_conflicts) == std::nullopt);
 BOOST_CHECK(all_conflicts == all_entries);
 auto conflicts_size = all_conflicts.size();
 all_conflicts.clear();

 add_descendants(tx2, 23, pool);
 BOOST_CHECK(GetEntriesForConflicts(*conflicts_with_parents.get(), pool, all_parents, all_conflicts) == std::nullopt);
 conflicts_size += 23;
 BOOST_CHECK_EQUAL(all_conflicts.size(), conflicts_size);
 all_conflicts.clear();

 add_descendants(tx4, 23, pool);
 BOOST_CHECK(GetEntriesForConflicts(*conflicts_with_parents.get(), pool, all_parents, all_conflicts) == std::nullopt);
 conflicts_size += 23;
 BOOST_CHECK_EQUAL(all_conflicts.size(), conflicts_size);
 all_conflicts.clear();

 add_descendants(tx6, 23, pool);
 BOOST_CHECK(GetEntriesForConflicts(*conflicts_with_parents.get(), pool, all_parents, all_conflicts) == std::nullopt);
 conflicts_size += 23;
 BOOST_CHECK_EQUAL(all_conflicts.size(), conflicts_size);
 all_conflicts.clear();

 add_descendants(tx7, 23, pool);
 BOOST_CHECK(GetEntriesForConflicts(*conflicts_with_parents.get(), pool, all_parents, all_conflicts) == std::nullopt);
 conflicts_size += 23;
 BOOST_CHECK_EQUAL(all_conflicts.size(), conflicts_size);
 BOOST_CHECK_EQUAL(all_conflicts.size(), 100);
 all_conflicts.clear();

 // Exceeds maximum number of conflicts.
 add_descendants(tx8, 1, pool);
 BOOST_CHECK(GetEntriesForConflicts(*conflicts_with_parents.get(), pool, all_parents, all_conflicts).has_value());

 // Tests for HasNoNewUnconfirmed
 const auto spends_unconfirmed = make_tx({tx1}, {36 * CENT});
 for (const auto& input : spends_unconfirmed->vin) {
 // Spends unconfirmed inputs.
 BOOST_CHECK(pool.exists(input.prevout.hash));
 }
 BOOST_CHECK(HasNoNewUnconfirmed(/*tx=*/ *spends_unconfirmed.get(),
 /*pool=*/ pool,
 /*iters_conflicting=*/ all_entries) == std::nullopt);
 BOOST_CHECK(HasNoNewUnconfirmed(*spends_unconfirmed.get(), pool, {entry2_normal}) == std::nullopt);
 BOOST_CHECK(HasNoNewUnconfirmed(*spends_unconfirmed.get(), pool, empty_set).has_value());

 const auto spends_new_unconfirmed = make_tx({tx1, tx8}, {36 * CENT});
 BOOST_CHECK(HasNoNewUnconfirmed(*spends_new_unconfirmed.get(), pool, {entry2_normal}).has_value());
 BOOST_CHECK(HasNoNewUnconfirmed(*spends_new_unconfirmed.get(), pool, all_entries).has_value());

 const auto spends_conflicting_confirmed = make_tx({m_coinbase_txns[0], m_coinbase_txns[1]}, {45 * CENT});
 BOOST_CHECK(HasNoNewUnconfirmed(*spends_conflicting_confirmed.get(), pool, {entry1_normal, entry3_low}) == std::nullopt);

 // Tests for CheckConflictTopology

 // Tx4 has 23 descendants
 BOOST_CHECK_EQUAL(pool.CheckConflictTopology(set_34_cpfp).value(), strprintf("%s has 24 descendants, max 1 allowed", entry3_low->GetSharedTx()->GetHash().ToString()));

 // No descendants yet
 BOOST_CHECK(pool.CheckConflictTopology({entry9_unchained}) == std::nullopt);

 // Add 1 descendant, still ok
 add_descendants(tx9, 1, pool);
 BOOST_CHECK(pool.CheckConflictTopology({entry9_unchained}) == std::nullopt);

 // N direct conflicts; ok
 BOOST_CHECK(pool.CheckConflictTopology({entry9_unchained, entry10_unchained, entry11_unchained}) == std::nullopt);

 // Add 1 descendant, still ok, even if it's considered a direct conflict as well
 const auto child_tx = add_descendants(tx10, 1, pool);
 const auto entry10_child = pool.GetIter(child_tx->GetHash()).value();
 BOOST_CHECK(pool.CheckConflictTopology({entry9_unchained, entry10_unchained, entry11_unchained}) == std::nullopt);
 BOOST_CHECK(pool.CheckConflictTopology({entry9_unchained, entry10_unchained, entry11_unchained, entry10_child}) == std::nullopt);

 // One more, size 3 cluster too much
 const auto grand_child_tx = add_descendants(child_tx, 1, pool);
 const auto entry10_grand_child = pool.GetIter(grand_child_tx->GetHash()).value();
 BOOST_CHECK_EQUAL(pool.CheckConflictTopology({entry9_unchained, entry10_unchained, entry11_unchained}).value(), strprintf("%s has 2 descendants, max 1 allowed", entry10_unchained->GetSharedTx()->GetHash().ToString()));
 // even if direct conflict is descendent itself
 BOOST_CHECK_EQUAL(pool.CheckConflictTopology({entry9_unchained, entry10_grand_child, entry11_unchained}).value(), strprintf("%s has 2 ancestors, max 1 allowed", entry10_grand_child->GetSharedTx()->GetHash().ToString()));

 // Make a single child from two singleton parents
 const auto two_parent_child_tx = add_descendant_to_parents({tx11, tx12}, pool);
 const auto entry_two_parent_child = pool.GetIter(two_parent_child_tx->GetHash()).value();
 BOOST_CHECK_EQUAL(pool.CheckConflictTopology({entry11_unchained}).value(), strprintf("%s is not the only parent of child %s", entry11_unchained->GetSharedTx()->GetHash().ToString(), entry_two_parent_child->GetSharedTx()->GetHash().ToString()));
 BOOST_CHECK_EQUAL(pool.CheckConflictTopology({entry12_unchained}).value(), strprintf("%s is not the only parent of child %s", entry12_unchained->GetSharedTx()->GetHash().ToString(), entry_two_parent_child->GetSharedTx()->GetHash().ToString()));
 BOOST_CHECK_EQUAL(pool.CheckConflictTopology({entry_two_parent_child}).value(), strprintf("%s has 2 ancestors, max 1 allowed", entry_two_parent_child->GetSharedTx()->GetHash().ToString()));

 // Single parent with two children, we will conflict with the siblings directly only
 const auto two_siblings = add_children_to_parent(tx13, pool);
 const auto entry_sibling_1 = pool.GetIter(two_siblings.first->GetHash()).value();
 const auto entry_sibling_2 = pool.GetIter(two_siblings.second->GetHash()).value();
 BOOST_CHECK_EQUAL(pool.CheckConflictTopology({entry_sibling_1}).value(), strprintf("%s is not the only child of parent %s", entry_sibling_1->GetSharedTx()->GetHash().ToString(), entry13_unchained->GetSharedTx()->GetHash().ToString()));
 BOOST_CHECK_EQUAL(pool.CheckConflictTopology({entry_sibling_2}).value(), strprintf("%s is not the only child of parent %s", entry_sibling_2->GetSharedTx()->GetHash().ToString(), entry13_unchained->GetSharedTx()->GetHash().ToString()));

}

BOOST_FIXTURE_TEST_CASE(improves_feerate, TestChain100Setup)
{
 CTxMemPool& pool = *Assert(m_node.mempool);
 LOCK2(::cs_main, pool.cs);
 TestMemPoolEntryHelper entry;

 const CAmount low_fee{CENT/100};
 const CAmount normal_fee{CENT/10};

 // low feerate parent with normal feerate child
 const auto tx1 = make_tx(/*inputs=*/ {m_coinbase_txns[0], m_coinbase_txns[1]}, /*output_values=*/ {10 * COIN});
 AddToMempool(pool, entry.Fee(low_fee).FromTx(tx1));
 const auto tx2 = make_tx(/*inputs=*/ {tx1}, /*output_values=*/ {995 * CENT});
 AddToMempool(pool, entry.Fee(normal_fee).FromTx(tx2));

 const auto entry1 = pool.GetIter(tx1->GetHash()).value();
 const auto tx1_fee = entry1->GetModifiedFee();
 const auto entry2 = pool.GetIter(tx2->GetHash()).value();
 const auto tx2_fee = entry2->GetModifiedFee();

 // conflicting transactions
 const auto tx1_conflict = make_tx(/*inputs=*/ {m_coinbase_txns[0], m_coinbase_txns[2]}, /*output_values=*/ {10 * COIN});
 const auto tx3 = make_tx(/*inputs=*/ {tx1_conflict}, /*output_values=*/ {995 * CENT});
 auto entry3 = entry.FromTx(tx3);

 // Now test ImprovesFeerateDiagram with various levels of "package rbf" feerates

 // It doesn't improve itself
 auto changeset = pool.GetChangeSet();
 changeset->StageRemoval(entry1);
 changeset->StageRemoval(entry2);
 changeset->StageAddition(tx1_conflict, tx1_fee, 0, 1, 0, false, 4, LockPoints());
 changeset->StageAddition(tx3, tx2_fee, 0, 1, 0, false, 4, LockPoints());
 const auto res1 = ImprovesFeerateDiagram(*changeset);
 BOOST_CHECK(res1.has_value());
 BOOST_CHECK(res1.value().first == DiagramCheckError::FAILURE);
 BOOST_CHECK(res1.value().second == "insufficient feerate: does not improve feerate diagram");

 // With one more satoshi it does
 changeset.reset();
 changeset = pool.GetChangeSet();
 changeset->StageRemoval(entry1);
 changeset->StageRemoval(entry2);
 changeset->StageAddition(tx1_conflict, tx1_fee+1, 0, 1, 0, false, 4, LockPoints());
 changeset->StageAddition(tx3, tx2_fee, 0, 1, 0, false, 4, LockPoints());
 BOOST_CHECK(ImprovesFeerateDiagram(*changeset) == std::nullopt);

 changeset.reset();
 // With prioritisation of in-mempool conflicts, it affects the results of the comparison using the same args as just above
 pool.PrioritiseTransaction(entry1->GetSharedTx()->GetHash(), /*nFeeDelta=*/1);
 changeset = pool.GetChangeSet();
 changeset->StageRemoval(entry1);
 changeset->StageRemoval(entry2);
 changeset->StageAddition(tx1_conflict, tx1_fee+1, 0, 1, 0, false, 4, LockPoints());
 changeset->StageAddition(tx3, tx2_fee, 0, 1, 0, false, 4, LockPoints());
 const auto res2 = ImprovesFeerateDiagram(*changeset);
 BOOST_CHECK(res2.has_value());
 BOOST_CHECK(res2.value().first == DiagramCheckError::FAILURE);
 BOOST_CHECK(res2.value().second == "insufficient feerate: does not improve feerate diagram");
 changeset.reset();

 pool.PrioritiseTransaction(entry1->GetSharedTx()->GetHash(), /*nFeeDelta=*/-1);

 // With fewer vbytes it does
 CMutableTransaction tx4{entry3.GetTx()};
 tx4.vin[0].scriptWitness = CScriptWitness(); // Clear out the witness, to reduce size
 auto entry4 = entry.FromTx(MakeTransactionRef(tx4));
 changeset = pool.GetChangeSet();
 changeset->StageRemoval(entry1);
 changeset->StageRemoval(entry2);
 changeset->StageAddition(tx1_conflict, tx1_fee, 0, 1, 0, false, 4, LockPoints());
 changeset->StageAddition(entry4.GetSharedTx(), tx2_fee, 0, 1, 0, false, 4, LockPoints());
 BOOST_CHECK(ImprovesFeerateDiagram(*changeset) == std::nullopt);
 changeset.reset();

 // Adding a grandchild makes the cluster size 3, which is uncalculable
 const auto tx5 = make_tx(/*inputs=*/ {tx2}, /*output_values=*/ {995 * CENT});
 AddToMempool(pool, entry.Fee(normal_fee).FromTx(tx5));
 const auto entry5 = pool.GetIter(tx5->GetHash()).value();

 changeset = pool.GetChangeSet();
 changeset->StageRemoval(entry1);
 changeset->StageRemoval(entry2);
 changeset->StageRemoval(entry5);
 changeset->StageAddition(tx1_conflict, tx1_fee, 0, 1, 0, false, 4, LockPoints());
 changeset->StageAddition(entry4.GetSharedTx(), tx2_fee + entry5->GetModifiedFee() + 1, 0, 1, 0, false, 4, LockPoints());
 const auto res3 = ImprovesFeerateDiagram(*changeset);
 BOOST_CHECK(res3.has_value());
 BOOST_CHECK(res3.value().first == DiagramCheckError::UNCALCULABLE);
 BOOST_CHECK_MESSAGE(res3.value().second == strprintf("%s has 2 descendants, max 1 allowed", tx1->GetHash().GetHex()), res3.value().second);
}

BOOST_FIXTURE_TEST_CASE(calc_feerate_diagram_rbf, TestChain100Setup)
{
 CTxMemPool& pool = *Assert(m_node.mempool);
 LOCK2(::cs_main, pool.cs);
 TestMemPoolEntryHelper entry;

 const CAmount low_fee{CENT/100};
 const CAmount normal_fee{CENT/10};
 const CAmount high_fee{CENT};

 // low -> high -> medium fee transactions that would result in two chunks together since they
 // are all same size
 const auto low_tx = make_tx(/*inputs=*/ {m_coinbase_txns[0]}, /*output_values=*/ {10 * COIN});
 AddToMempool(pool, entry.Fee(low_fee).FromTx(low_tx));

 const auto entry_low = pool.GetIter(low_tx->GetHash()).value();
 const auto low_size = entry_low->GetTxSize();

 const auto replacement_tx = make_tx(/*inputs=*/ {m_coinbase_txns[0]}, /*output_values=*/ {9 * COIN});
 auto entry_replacement = entry.FromTx(replacement_tx);

 // Replacement of size 1
 {
 auto changeset = pool.GetChangeSet();
 changeset->StageRemoval(entry_low);
 changeset->StageAddition(replacement_tx, 0, 0, 1, 0, false, 4, LockPoints());
 const auto replace_one{changeset->CalculateChunksForRBF()};
 BOOST_CHECK(replace_one.has_value());
 std::vector<FeeFrac> expected_old_chunks{{low_fee, low_size}};
 BOOST_CHECK(replace_one->first == expected_old_chunks);
 std::vector<FeeFrac> expected_new_chunks{{0, int32_t(entry_replacement.GetTxSize())}};
 BOOST_CHECK(replace_one->second == expected_new_chunks);
 }

 // Non-zero replacement fee/size
 {
 auto changeset = pool.GetChangeSet();
 changeset->StageRemoval(entry_low);
 changeset->StageAddition(replacement_tx, high_fee, 0, 1, 0, false, 4, LockPoints());
 const auto replace_one_fee{changeset->CalculateChunksForRBF()};
 BOOST_CHECK(replace_one_fee.has_value());
 std::vector<FeeFrac> expected_old_diagram{{low_fee, low_size}};
 BOOST_CHECK(replace_one_fee->first == expected_old_diagram);
 std::vector<FeeFrac> expected_new_diagram{{high_fee, low_size}};
 BOOST_CHECK(replace_one_fee->second == expected_new_diagram);
 }

 // Add a second transaction to the cluster that will make a single chunk, to be evicted in the RBF
 const auto high_tx = make_tx(/*inputs=*/ {low_tx}, /*output_values=*/ {995 * CENT});
 AddToMempool(pool, entry.Fee(high_fee).FromTx(high_tx));
 const auto entry_high = pool.GetIter(high_tx->GetHash()).value();
 const auto high_size = entry_high->GetTxSize();

 {
 auto changeset = pool.GetChangeSet();
 changeset->StageRemoval(entry_low);
 changeset->StageRemoval(entry_high);
 changeset->StageAddition(replacement_tx, high_fee, 0, 1, 0, false, 4, LockPoints());
 const auto replace_single_chunk{changeset->CalculateChunksForRBF()};
 BOOST_CHECK(replace_single_chunk.has_value());
 std::vector<FeeFrac> expected_old_chunks{{low_fee + high_fee, low_size + high_size}};
 BOOST_CHECK(replace_single_chunk->first == expected_old_chunks);
 std::vector<FeeFrac> expected_new_chunks{{high_fee, low_size}};
 BOOST_CHECK(replace_single_chunk->second == expected_new_chunks);
 }

 // Conflict with the 2nd tx, resulting in new diagram with three entries
 {
 auto changeset = pool.GetChangeSet();
 changeset->StageRemoval(entry_high);
 changeset->StageAddition(replacement_tx, high_fee, 0, 1, 0, false, 4, LockPoints());
 const auto replace_cpfp_child{changeset->CalculateChunksForRBF()};
 BOOST_CHECK(replace_cpfp_child.has_value());
 std::vector<FeeFrac> expected_old_chunks{{low_fee + high_fee, low_size + high_size}};
 BOOST_CHECK(replace_cpfp_child->first == expected_old_chunks);
 std::vector<FeeFrac> expected_new_chunks{{high_fee, low_size}, {low_fee, low_size}};
 BOOST_CHECK(replace_cpfp_child->second == expected_new_chunks);
 }

 // third transaction causes the topology check to fail
 const auto normal_tx = make_tx(/*inputs=*/ {high_tx}, /*output_values=*/ {995 * CENT});
 AddToMempool(pool, entry.Fee(normal_fee).FromTx(normal_tx));
 const auto entry_normal = pool.GetIter(normal_tx->GetHash()).value();

 {
 auto changeset = pool.GetChangeSet();
 changeset->StageRemoval(entry_low);
 changeset->StageRemoval(entry_high);
 changeset->StageRemoval(entry_normal);
 changeset->StageAddition(replacement_tx, high_fee, 0, 1, 0, false, 4, LockPoints());
 const auto replace_too_large{changeset->CalculateChunksForRBF()};
 BOOST_CHECK(!replace_too_large.has_value());
 BOOST_CHECK_EQUAL(util::ErrorString(replace_too_large).original, strprintf("%s has both ancestor and descendant, exceeding cluster limit of 2", high_tx->GetHash().GetHex()));
 }

 // Make a size 2 cluster that is itself two chunks; evict both txns
 const auto high_tx_2 = make_tx(/*inputs=*/ {m_coinbase_txns[1]}, /*output_values=*/ {10 * COIN});
 AddToMempool(pool, entry.Fee(high_fee).FromTx(high_tx_2));
 const auto entry_high_2 = pool.GetIter(high_tx_2->GetHash()).value();
 const auto high_size_2 = entry_high_2->GetTxSize();

 const auto low_tx_2 = make_tx(/*inputs=*/ {high_tx_2}, /*output_values=*/ {9 * COIN});
 AddToMempool(pool, entry.Fee(low_fee).FromTx(low_tx_2));
 const auto entry_low_2 = pool.GetIter(low_tx_2->GetHash()).value();
 const auto low_size_2 = entry_low_2->GetTxSize();

 {
 auto changeset = pool.GetChangeSet();
 changeset->StageRemoval(entry_high_2);
 changeset->StageRemoval(entry_low_2);
 changeset->StageAddition(replacement_tx, high_fee, 0, 1, 0, false, 4, LockPoints());
 const auto replace_two_chunks_single_cluster{changeset->CalculateChunksForRBF()};
 BOOST_CHECK(replace_two_chunks_single_cluster.has_value());
 std::vector<FeeFrac> expected_old_chunks{{high_fee, high_size_2}, {low_fee, low_size_2}};
 BOOST_CHECK(replace_two_chunks_single_cluster->first == expected_old_chunks);
 std::vector<FeeFrac> expected_new_chunks{{high_fee, low_size_2}};
 BOOST_CHECK(replace_two_chunks_single_cluster->second == expected_new_chunks);
 }

 // You can have more than two direct conflicts if there are multiple affected clusters, all of size 2 or less
 const auto conflict_1 = make_tx(/*inputs=*/ {m_coinbase_txns[2]}, /*output_values=*/ {10 * COIN});
 AddToMempool(pool, entry.Fee(low_fee).FromTx(conflict_1));
 const auto conflict_1_entry = pool.GetIter(conflict_1->GetHash()).value();

 const auto conflict_2 = make_tx(/*inputs=*/ {m_coinbase_txns[3]}, /*output_values=*/ {10 * COIN});
 AddToMempool(pool, entry.Fee(low_fee).FromTx(conflict_2));
 const auto conflict_2_entry = pool.GetIter(conflict_2->GetHash()).value();

 const auto conflict_3 = make_tx(/*inputs=*/ {m_coinbase_txns[4]}, /*output_values=*/ {10 * COIN});
 AddToMempool(pool, entry.Fee(low_fee).FromTx(conflict_3));
 const auto conflict_3_entry = pool.GetIter(conflict_3->GetHash()).value();

 {
 auto changeset = pool.GetChangeSet();
 changeset->StageRemoval(conflict_1_entry);
 changeset->StageRemoval(conflict_2_entry);
 changeset->StageRemoval(conflict_3_entry);
 changeset->StageAddition(replacement_tx, high_fee, 0, 1, 0, false, 4, LockPoints());
 const auto replace_multiple_clusters{changeset->CalculateChunksForRBF()};
 BOOST_CHECK(replace_multiple_clusters.has_value());
 BOOST_CHECK(replace_multiple_clusters->first.size() == 3);
 BOOST_CHECK(replace_multiple_clusters->second.size() == 1);
 }

 // Add a child transaction to conflict_1 and make it cluster size 2, two chunks due to same feerate
 const auto conflict_1_child = make_tx(/*inputs=*/{conflict_1}, /*output_values=*/ {995 * CENT});
 AddToMempool(pool, entry.Fee(low_fee).FromTx(conflict_1_child));
 const auto conflict_1_child_entry = pool.GetIter(conflict_1_child->GetHash()).value();

 {
 auto changeset = pool.GetChangeSet();
 changeset->StageRemoval(conflict_1_entry);
 changeset->StageRemoval(conflict_2_entry);
 changeset->StageRemoval(conflict_3_entry);
 changeset->StageRemoval(conflict_1_child_entry);
 changeset->StageAddition(replacement_tx, high_fee, 0, 1, 0, false, 4, LockPoints());
 const auto replace_multiple_clusters_2{changeset->CalculateChunksForRBF()};

 BOOST_CHECK(replace_multiple_clusters_2.has_value());
 BOOST_CHECK(replace_multiple_clusters_2->first.size() == 4);
 BOOST_CHECK(replace_multiple_clusters_2->second.size() == 1);
 }

 // Add another descendant to conflict_1, making the cluster size > 2 should fail at this point.
 const auto conflict_1_grand_child = make_tx(/*inputs=*/{conflict_1_child}, /*output_values=*/ {995 * CENT});
 AddToMempool(pool, entry.Fee(high_fee).FromTx(conflict_1_grand_child));
 const auto conflict_1_grand_child_entry = pool.GetIter(conflict_1_child->GetHash()).value();

 {
 auto changeset = pool.GetChangeSet();
 changeset->StageRemoval(conflict_1_entry);
 changeset->StageRemoval(conflict_2_entry);
 changeset->StageRemoval(conflict_3_entry);
 changeset->StageRemoval(conflict_1_child_entry);
 changeset->StageRemoval(conflict_1_grand_child_entry);
 changeset->StageAddition(replacement_tx, high_fee, 0, 1, 0, false, 4, LockPoints());
 const auto replace_cluster_size_3{changeset->CalculateChunksForRBF()};

 BOOST_CHECK(!replace_cluster_size_3.has_value());
 BOOST_CHECK_EQUAL(util::ErrorString(replace_cluster_size_3).original, strprintf("%s has 2 descendants, max 1 allowed", conflict_1->GetHash().GetHex()));
 }
}

BOOST_AUTO_TEST_CASE(feerate_chunks_utilities)
{
 // Sanity check the correctness of the feerate chunks comparison.

 // A strictly better case.
 std::vector<FeeFrac> old_chunks{{{950, 300}, {100, 100}}};
 std::vector<FeeFrac> new_chunks{{{1000, 300}, {50, 100}}};

 BOOST_CHECK(std::is_lt(CompareChunks(old_chunks, new_chunks)));
 BOOST_CHECK(std::is_gt(CompareChunks(new_chunks, old_chunks)));

 // Incomparable diagrams
 old_chunks = {{950, 300}, {100, 100}};
 new_chunks = {{1000, 300}, {0, 100}};

 BOOST_CHECK(CompareChunks(old_chunks, new_chunks) == std::partial_ordering::unordered);
 BOOST_CHECK(CompareChunks(new_chunks, old_chunks) == std::partial_ordering::unordered);

 // Strictly better but smaller size.
 old_chunks = {{950, 300}, {100, 100}};
 new_chunks = {{1100, 300}};

 BOOST_CHECK(std::is_lt(CompareChunks(old_chunks, new_chunks)));
 BOOST_CHECK(std::is_gt(CompareChunks(new_chunks, old_chunks)));

 // New diagram is strictly better due to the first chunk, even though
 // second chunk contributes no fees
 old_chunks = {{950, 300}, {100, 100}};
 new_chunks = {{1100, 100}, {0, 100}};

 BOOST_CHECK(std::is_lt(CompareChunks(old_chunks, new_chunks)));
 BOOST_CHECK(std::is_gt(CompareChunks(new_chunks, old_chunks)));

 // Feerate of first new chunk is better with, but second chunk is worse
 old_chunks = {{950, 300}, {100, 100}};
 new_chunks = {{750, 100}, {249, 250}, {151, 650}};

 BOOST_CHECK(CompareChunks(old_chunks, new_chunks) == std::partial_ordering::unordered);
 BOOST_CHECK(CompareChunks(new_chunks, old_chunks) == std::partial_ordering::unordered);

 // If we make the second chunk slightly better, the new diagram now wins.
 old_chunks = {{950, 300}, {100, 100}};
 new_chunks = {{750, 100}, {250, 250}, {150, 150}};

 BOOST_CHECK(std::is_lt(CompareChunks(old_chunks, new_chunks)));
 BOOST_CHECK(std::is_gt(CompareChunks(new_chunks, old_chunks)));

 // Identical diagrams, cannot be strictly better
 old_chunks = {{950, 300}, {100, 100}};
 new_chunks = {{950, 300}, {100, 100}};

 BOOST_CHECK(std::is_eq(CompareChunks(old_chunks, new_chunks)));
 BOOST_CHECK(std::is_eq(CompareChunks(new_chunks, old_chunks)));

 // Same aggregate fee, but different total size (trigger single tail fee check step)
 old_chunks = {{950, 300}, {100, 99}};
 new_chunks = {{950, 300}, {100, 100}};

 // No change in evaluation when tail check needed.
 BOOST_CHECK(std::is_gt(CompareChunks(old_chunks, new_chunks)));
 BOOST_CHECK(std::is_lt(CompareChunks(new_chunks, old_chunks)));

 // Trigger multiple tail fee check steps
 old_chunks = {{950, 300}, {100, 99}};
 new_chunks = {{950, 300}, {100, 100}, {0, 1}, {0, 1}};

 BOOST_CHECK(std::is_gt(CompareChunks(old_chunks, new_chunks)));
 BOOST_CHECK(std::is_lt(CompareChunks(new_chunks, old_chunks)));

 // Multiple tail fee check steps, unordered result
 new_chunks = {{950, 300}, {100, 100}, {0, 1}, {0, 1}, {1, 1}};
 BOOST_CHECK(CompareChunks(old_chunks, new_chunks) == std::partial_ordering::unordered);
 BOOST_CHECK(CompareChunks(new_chunks, old_chunks) == std::partial_ordering::unordered);
}

BOOST_AUTO_TEST_SUITE_END()