[validation] add AcceptSubPackage to delegate Accept* calls and clean up m_view

(1) Call AcceptSingleTransaction when there is only 1 transaction in the
  subpackage. This avoids calling PackageMempoolChecks() which enforces
rules that don't need to be applied for a single transaction, i.e.
disabling CPFP carve out.
There is a slight change in the error type returned, as shown in the
txpackage_tests change.  When a transaction is the last one left in the
package and its fee is too low, this returns a PCKG_TX instead of
PCKG_POLICY. This interface is clearer; "package-fee-too-low" for 1
transaction would be a bit misleading.

(2) Clean up m_view and m_viewmempool so that coins created in this
sub-package evaluation are not available for other sub-package
evaluations. The contents of the mempool may change, so coins that are
available now might not be later.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/test/txpackage_tests.cpp b/src/test/txpackage_tests.cpp
index 01f0a836a3..118a963c75 100644
--- a/src/test/txpackage_tests.cpp
+++ b/src/test/txpackage_tests.cpp
@@ -821,18 +821,20 @@ BOOST_FIXTURE_TEST_CASE(package_cpfp_tests, TestChain100Setup)
         expected_pool_size += 1;
         BOOST_CHECK_MESSAGE(submit_rich_parent.m_state.IsInvalid(), "Package validation unexpectedly succeeded");
 
-        // The child would have been validated on its own and failed, then submitted as a "package" of 1.
+        // The child would have been validated on its own and failed.
         BOOST_CHECK_EQUAL(submit_rich_parent.m_state.GetResult(), PackageValidationResult::PCKG_TX);
         BOOST_CHECK_EQUAL(submit_rich_parent.m_state.GetRejectReason(), "transaction failed");
 
         auto it_parent = submit_rich_parent.m_tx_results.find(tx_parent_rich->GetWitnessHash());
+        auto it_child = submit_rich_parent.m_tx_results.find(tx_child_poor->GetWitnessHash());
         BOOST_CHECK(it_parent != submit_rich_parent.m_tx_results.end());
+        BOOST_CHECK(it_child != submit_rich_parent.m_tx_results.end());
         BOOST_CHECK(it_parent->second.m_result_type == MempoolAcceptResult::ResultType::VALID);
+        BOOST_CHECK(it_child->second.m_result_type == MempoolAcceptResult::ResultType::INVALID);
         BOOST_CHECK(it_parent->second.m_state.GetRejectReason() == "");
         BOOST_CHECK_MESSAGE(it_parent->second.m_base_fees.value() == high_parent_fee,
                 strprintf("rich parent: expected fee %s, got %s", high_parent_fee, it_parent->second.m_base_fees.value()));
         BOOST_CHECK(it_parent->second.m_effective_feerate == CFeeRate(high_parent_fee, GetVirtualTransactionSize(*tx_parent_rich)));
-        auto it_child = submit_rich_parent.m_tx_results.find(tx_child_poor->GetWitnessHash());
         BOOST_CHECK(it_child != submit_rich_parent.m_tx_results.end());
         BOOST_CHECK_EQUAL(it_child->second.m_result_type, MempoolAcceptResult::ResultType::INVALID);
         BOOST_CHECK_EQUAL(it_child->second.m_state.GetResult(), TxValidationResult::TX_MEMPOOL_POLICY);