tests: Add fuzzing harness for CBlockPolicyEstimator::{Read,Write} (policy/fees.h)

src/test/fuzz/policy_estimator_io.cpp

@@ -0,0 +1,28 @@
+// Copyright (c) 2020 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <policy/fees.h>
+#include <test/fuzz/FuzzedDataProvider.h>
+#include <test/fuzz/fuzz.h>
+#include <test/fuzz/util.h>
+
+#include <cstdint>
+#include <vector>
+
+void initialize()
+{
+    InitializeFuzzingContext();
+}
+
+void test_one_input(const std::vector<uint8_t>& buffer)
+{
+    FuzzedDataProvider fuzzed_data_provider(buffer.data(), buffer.size());
+    FuzzedAutoFileProvider fuzzed_auto_file_provider = ConsumeAutoFile(fuzzed_data_provider);
+    CAutoFile fuzzed_auto_file = fuzzed_auto_file_provider.open();
+    // Re-using block_policy_estimator across runs to avoid costly creation of CBlockPolicyEstimator object.
+    static CBlockPolicyEstimator block_policy_estimator;
+    if (block_policy_estimator.Read(fuzzed_auto_file)) {
+        block_policy_estimator.Write(fuzzed_auto_file);
+    }
+}