tests: Add coverage of {,Incremental}DynamicUsage(const std::set<X, Y>& s) to existing fuzzer

Author: practicalswift

src/test/fuzz/integer.cpp

@@ -36,6 +36,7 @@
 #include <cassert>
 #include <chrono>
 #include <limits>
+#include <set>
 #include <vector>
 
 void initialize()
@@ -114,6 +115,12 @@ void test_one_input(const std::vector<uint8_t>& buffer)
     (void)memusage::DynamicUsage(u8);
     const unsigned char uch = static_cast<unsigned char>(u8);
     (void)memusage::DynamicUsage(uch);
+    {
+        const std::set<int64_t> i64s{i64, static_cast<int64_t>(u64)};
+        const size_t dynamic_usage = memusage::DynamicUsage(i64s);
+        const size_t incremental_dynamic_usage = memusage::IncrementalDynamicUsage(i64s);
+        assert(dynamic_usage == incremental_dynamic_usage * i64s.size());
+    }
     (void)MillisToTimeval(i64);
     const double d = ser_uint64_to_double(u64);
     assert(ser_double_to_uint64(d) == u64);