[fuzz] add ProcessNewPackage call in tx_pool fuzzer

Author: glozow

src/test/fuzz/tx_pool.cpp

@@ -218,6 +218,16 @@ FUZZ_TARGET_INIT(tx_pool_standard, initialize_tx_pool)
         RegisterSharedValidationInterface(txr);
         const bool bypass_limits = fuzzed_data_provider.ConsumeBool();
         ::fRequireStandard = fuzzed_data_provider.ConsumeBool();
+
+        // Make sure ProcessNewPackage on one transaction works and always fully validates the transaction.
+        // The result is not guaranteed to be the same as what is returned by ATMP.
+        const auto result_package = WITH_LOCK(::cs_main,
+                                    return ProcessNewPackage(node.chainman->ActiveChainstate(), tx_pool, {tx}, true));
+        auto it = result_package.m_tx_results.find(tx->GetWitnessHash());
+        Assert(it != result_package.m_tx_results.end());
+        Assert(it->second.m_result_type == MempoolAcceptResult::ResultType::VALID ||
+               it->second.m_result_type == MempoolAcceptResult::ResultType::INVALID);
+
         const auto res = WITH_LOCK(::cs_main, return AcceptToMemoryPool(chainstate, tx_pool, tx, bypass_limits));
         const bool accepted = res.m_result_type == MempoolAcceptResult::ResultType::VALID;
         SyncWithValidationInterfaceQueue();