From e18d392689da72d857fc590097889060a48d98e0 Mon Sep 17 00:00:00 2001
From: ismaelsadeeq <abubakarsadiqismail@proton.me>
Date: Mon, 12 Jan 2026 13:52:54 +0000
Subject: [PATCH] test: add mempool estimator i/o fuzz test

---
 src/test/fuzz/policy_estimator_io.cpp | 34 ++++++++++++++++++++-------
 1 file changed, 26 insertions(+), 8 deletions(-)

diff --git a/src/test/fuzz/policy_estimator_io.cpp b/src/test/fuzz/policy_estimator_io.cpp
index 10dad417aec..2d0edaa2fdf 100644
--- a/src/test/fuzz/policy_estimator_io.cpp
+++ b/src/test/fuzz/policy_estimator_io.cpp
@@ -4,6 +4,7 @@
 
 #include <policy/fees/block_policy_estimator.h>
 #include <policy/fees/estimator_args.h>
+#include <policy/fees/mempool_estimator.h>
 #include <streams.h>
 #include <test/fuzz/FuzzedDataProvider.h>
 #include <test/fuzz/fuzz.h>
@@ -13,12 +14,13 @@
 #include <memory>
 
 namespace {
-const BasicTestingSetup* g_setup;
+const TestingSetup* g_setup;
 } // namespace
 
 void initialize_policy_estimator_io()
 {
-    static const auto testing_setup = MakeNoLogFileContext<>();
+    static const auto testing_setup{
+        MakeNoLogFileContext<const TestingSetup>(ChainType::REGTEST, TestOpts{.setup_net = false})};
     g_setup = testing_setup.get();
 }
 
@@ -26,11 +28,27 @@ FUZZ_TARGET(policy_estimator_io, .init = initialize_policy_estimator_io)
 {
     FuzzedDataProvider fuzzed_data_provider(buffer.data(), buffer.size());
     FuzzedFileProvider fuzzed_file_provider{fuzzed_data_provider};
-    AutoFile fuzzed_auto_file{fuzzed_file_provider.open()};
-    // Reusing block_policy_estimator across runs to avoid costly creation of CBlockPolicyEstimator object.
-    static CBlockPolicyEstimator block_policy_estimator{BlockPolicyFeeEstPath(*g_setup->m_node.args), DEFAULT_ACCEPT_STALE_FEE_ESTIMATES};
-    if (block_policy_estimator.Read(fuzzed_auto_file)) {
-        block_policy_estimator.Write(fuzzed_auto_file);
+    // Reuse estimators across runs to avoid costly object creation.
+    static CBlockPolicyEstimator block_policy_estimator{
+        BlockPolicyFeeEstPath(*g_setup->m_node.args), DEFAULT_ACCEPT_STALE_FEE_ESTIMATES};
+    {
+        AutoFile fuzzed_auto_file_block_policy{fuzzed_file_provider.open()};
+        if (block_policy_estimator.Read(fuzzed_auto_file_block_policy)) {
+            block_policy_estimator.Write(fuzzed_auto_file_block_policy);
+        }
+        (void)fuzzed_auto_file_block_policy.fclose();
+    }
+    static MemPoolFeeRateEstimator mempool_feerate_estimator{
+        MempoolPolicyEstimatorPath(*g_setup->m_node.args),
+        *g_setup->m_node.mempool,
+        *g_setup->m_node.chainman};
+    {
+        AutoFile fuzzed_auto_file_mempool_policy{fuzzed_file_provider.open()};
+        if (mempool_feerate_estimator.Read(fuzzed_auto_file_mempool_policy)) {
+            mempool_feerate_estimator.Write(fuzzed_auto_file_mempool_policy);
+        }
+        // Write() does not take ownership; close explicitly because it may
+        // have written to the fuzzed file.
+        (void)fuzzed_auto_file_mempool_policy.fclose();
     }
-    (void)fuzzed_auto_file.fclose();
 }