test: Mock IBD in net_processing fuzzers

src/test/util/validation.h

@@ -0,0 +1,17 @@
+// 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.
+
+#ifndef BITCOIN_TEST_UTIL_VALIDATION_H
+#define BITCOIN_TEST_UTIL_VALIDATION_H
+
+#include <validation.h>
+
+struct TestChainState : public CChainState {
+    /** Reset the ibd cache to its initial state */
+    void ResetIbd();
+    /** Toggle IsInitialBlockDownload from true to false */
+    void JumpOutOfIbd();
+};
+
+#endif // BITCOIN_TEST_UTIL_VALIDATION_H