From 457cfb61b5323a13218b3cfb5a6a6d8b3a7c5f7f Mon Sep 17 00:00:00 2001
From: glozow <gloriajzhao@gmail.com>
Date: Wed, 30 Jul 2025 15:48:34 -0400
Subject: [PATCH] [prep/util] help MockMempoolMinFee handle more precise
 feerates

Use a virtual size of 1000 to keep precision when using a feerate
(which is rounded to the nearest satoshi per kvb) that isn't just an
integer.
---
 src/test/util/setup_common.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/test/util/setup_common.cpp b/src/test/util/setup_common.cpp
index 76a42d19ea2..9c9bdc70ccd 100644
--- a/src/test/util/setup_common.cpp
+++ b/src/test/util/setup_common.cpp
@@ -40,6 +40,7 @@
 #include <test/util/coverage.h>
 #include <test/util/net.h>
 #include <test/util/random.h>
+#include <test/util/transaction_utils.h>
 #include <test/util/txmempool.h>
 #include <txdb.h>
 #include <txmempool.h>
@@ -586,6 +587,9 @@ void TestChain100Setup::MockMempoolMinFee(const CFeeRate& target_feerate)
     CMutableTransaction mtx = CMutableTransaction();
     mtx.vin.emplace_back(COutPoint{Txid::FromUint256(m_rng.rand256()), 0});
     mtx.vout.emplace_back(1 * COIN, GetScriptForDestination(WitnessV0ScriptHash(CScript() << OP_TRUE)));
+    // Set a large size so that the fee evaluated at target_feerate (which is usually in sats/kvB) is an integer.
+    // Otherwise, GetMinFee() may end up slightly different from target_feerate.
+    BulkTransaction(mtx, 4000);
     const auto tx{MakeTransactionRef(mtx)};
     LockPoints lp;
     // The new mempool min feerate is equal to the removed package's feerate + incremental feerate.