tests: Add Parse(...) (descriptor) fuzzing harness

src/test/fuzz/descriptor_parse.cpp

@@ -0,0 +1,22 @@
+// Copyright (c) 2009-2019 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 <chainparams.h>
+#include <script/descriptor.h>
+#include <test/fuzz/fuzz.h>
+
+void initialize()
+{
+    SelectParams(CBaseChainParams::REGTEST);
+}
+
+void test_one_input(const std::vector<uint8_t>& buffer)
+{
+    const std::string descriptor(buffer.begin(), buffer.end());
+    FlatSigningProvider signing_provider;
+    std::string error;
+    for (const bool require_checksum : {true, false}) {
+        Parse(descriptor, signing_provider, error, require_checksum);
+    }
+}