Method TestPackageSelection

src/test/miner_tests.cpp:89–192

Test suite for ancestor feerate transaction selection. Implemented as an additional function, rather than a separate test case, to allow reusing the blockchain created in CreateNewBlock_validity.

// Implemented as an additional function, rather than a separate test case,
// to allow reusing the blockchain created in CreateNewBlock_validity.
void MinerTestingSetup::TestPackageSelection(const CChainParams& chainparams, const CScript& scriptPubKey, const std::vector<CTransactionRef>& txFirst)
{
    // Test the ancestor feerate transaction selection.
    TestMemPoolEntryHelper entry;

    // Test that a medium fee transaction will be selected after a higher fee
    // rate package with a low fee rate parent.
    CMutableTransaction tx;
    tx.vin.resize(1);
    tx.vin[0].scriptSig = CScript() << OP_1;
    tx.vin[0].prevout.hash = txFirst[0]->GetHash();
    tx.vin[0].prevout.n = 0;
    tx.vout.resize(1);
    tx.vout[0].nValue = 5000000000LL - 1000;
    // This tx has a low fee: 1000 satoshis
    uint256 hashParentTx = tx.GetHash(); // save this txid for later use
    m_node.mempool->addUnchecked(entry.Fee(1000).Time(GetTime()).SpendsCoinbase(true).FromTx(tx));

    // This tx has a medium fee: 10000 satoshis
    tx.vin[0].prevout.hash = txFirst[1]->GetHash();
    tx.vout[0].nValue = 5000000000LL - 10000;
    uint256 hashMediumFeeTx = tx.GetHash();
    m_node.mempool->addUnchecked(entry.Fee(10000).Time(GetTime()).SpendsCoinbase(true).FromTx(tx));

    // This tx has a high fee, but depends on the first transaction
    tx.vin[0].prevout.hash = hashParentTx;
    tx.vout[0].nValue = 5000000000LL - 1000 - 50000; // 50k satoshi fee
    uint256 hashHighFeeTx = tx.GetHash();
    m_node.mempool->addUnchecked(entry.Fee(50000).Time(GetTime()).SpendsCoinbase(false).FromTx(tx));

    std::unique_ptr<CBlockTemplate> pblocktemplate = AssemblerForTest(chainparams).CreateNewBlock(scriptPubKey);
    BOOST_REQUIRE_EQUAL(pblocktemplate->block.vtx.size(), 4U);
    BOOST_CHECK(pblocktemplate->block.vtx[1]->GetHash() == hashParentTx);
    BOOST_CHECK(pblocktemplate->block.vtx[2]->GetHash() == hashHighFeeTx);
    BOOST_CHECK(pblocktemplate->block.vtx[3]->GetHash() == hashMediumFeeTx);

    // Test that a package below the block min tx fee doesn't get included
    tx.vin[0].prevout.hash = hashHighFeeTx;
    tx.vout[0].nValue = 5000000000LL - 1000 - 50000; // 0 fee
    uint256 hashFreeTx = tx.GetHash();
    m_node.mempool->addUnchecked(entry.Fee(0).FromTx(tx));
    size_t freeTxSize = ::GetSerializeSize(tx, PROTOCOL_VERSION);

    // Calculate a fee on child transaction that will put the package just
    // below the block min tx fee (assuming 1 child tx of the same size).
    CAmount feeToUse = blockMinFeeRate.GetFee(2*freeTxSize) - 1;

    tx.vin[0].prevout.hash = hashFreeTx;
    tx.vout[0].nValue = 5000000000LL - 1000 - 50000 - feeToUse;
    uint256 hashLowFeeTx = tx.GetHash();
    m_node.mempool->addUnchecked(entry.Fee(feeToUse).FromTx(tx));
    pblocktemplate = AssemblerForTest(chainparams).CreateNewBlock(scriptPubKey);
    // Verify that the free tx and the low fee tx didn't get selected
    for (size_t i=0; i<pblocktemplate->block.vtx.size(); ++i) {
        BOOST_CHECK(pblocktemplate->block.vtx[i]->GetHash() != hashFreeTx);
        BOOST_CHECK(pblocktemplate->block.vtx[i]->GetHash() != hashLowFeeTx);
    }