tests: Add fuzzing coverage for TransactionErrorString(...)

src/test/fuzz/kitchen_sink.cpp

@@ -0,0 +1,22 @@
+// 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 <test/fuzz/FuzzedDataProvider.h>
+#include <test/fuzz/fuzz.h>
+#include <test/fuzz/util.h>
+#include <util/error.h>
+
+#include <cstdint>
+#include <vector>
+
+// The fuzzing kitchen sink: Fuzzing harness for functions that need to be
+// fuzzed but a.) don't belong in any existing fuzzing harness file, and
+// b.) are not important enough to warrant their own fuzzing harness file.
+void test_one_input(const std::vector<uint8_t>& buffer)
+{
+    FuzzedDataProvider fuzzed_data_provider(buffer.data(), buffer.size());
+
+    const TransactionError transaction_error = fuzzed_data_provider.PickValueInArray<TransactionError>({TransactionError::OK, TransactionError::MISSING_INPUTS, TransactionError::ALREADY_IN_CHAIN, TransactionError::P2P_DISABLED, TransactionError::MEMPOOL_REJECTED, TransactionError::MEMPOOL_ERROR, TransactionError::INVALID_PSBT, TransactionError::PSBT_MISMATCH, TransactionError::SIGHASH_MISMATCH, TransactionError::MAX_FEE_EXCEEDED});
+    (void)TransactionErrorString(transaction_error);
+}