fuzz: Consolidate fuzzing TestingSetup initialization

Previously, the {Basic,}TestingSetup for fuzzers were set up in many ways:

1. Calling InitializeFuzzingContext, which implicitly constructs a static
   const BasicTestingSetup
2. Directly constructing a static const BasicTestingSetup in the initialize_*
   function
3. Directly constructing a static TestingSetup and reproducing the
   initialization arguments (I'm assuming because
   InitializeFuzzingContext only initializes a BasicTestingSetup)

The new, relatively-simple MakeFuzzingContext function allows us to
consolidate these methods of initialization by being flexible enough to
be used in all situations. It:

1. Is templated so that we can choose to initialize any of
   the *TestingSetup classes
2. Has sane defaults which are often used in fuzzers but are also
   easily overridable
3. Returns a unique_ptr, explicitly transferring ownership to the caller
   to deal with according to its situation

1 files changed, 11 insertions, 2 deletions

diff --git a/src/test/fuzz/util.h b/src/test/fuzz/util.h
index b7cf395e76..7796f77cc6 100644
--- a/src/test/fuzz/util.h
+++ b/src/test/fuzz/util.h
@@ -27,6 +27,7 @@
 #include <txmempool.h>
 #include <uint256.h>
 #include <util/time.h>
+#include <util/vector.h>
 #include <version.h>
 
 #include <algorithm>
@@ -338,9 +339,17 @@ inline void FillNode(FuzzedDataProvider& fuzzed_data_provider, CNode& node, cons
     }
 }
 
-inline void InitializeFuzzingContext(const std::string& chain_name = CBaseChainParams::REGTEST)
+template <class T = const BasicTestingSetup>
+std::unique_ptr<T> MakeFuzzingContext(const std::string& chain_name = CBaseChainParams::REGTEST, const std::vector<const char*>& extra_args = {})
 {
-    static const BasicTestingSetup basic_testing_setup{chain_name, {"-nodebuglogfile"}};
+    // Prepend default arguments for fuzzing
+    const std::vector<const char*> arguments = Cat(
+        {
+            "-nodebuglogfile",
+        },
+        extra_args);
+
+    return MakeUnique<T>(chain_name, arguments);
 }
 
 class FuzzedFileProvider