tests: Clarify how we avoid hitting the signed integer overflow in CFeeRate::GetFeePerK() when fuzzing

Author: practicalswift

src/test/fuzz/util.h

@@ -104,7 +104,10 @@ NODISCARD inline CTxMemPoolEntry ConsumeTxMemPoolEntry(FuzzedDataProvider& fuzze
 {
     // Avoid:
     // policy/feerate.cpp:28:34: runtime error: signed integer overflow: 34873208148477500 * 1000 cannot be represented in type 'long'
-    const CAmount fee = ConsumeMoney(fuzzed_data_provider) / static_cast<CAmount>(100);
+    //
+    // Reproduce using CFeeRate(348732081484775, 10).GetFeePerK()
+    const CAmount fee = std::min<CAmount>(ConsumeMoney(fuzzed_data_provider), std::numeric_limits<CAmount>::max() / static_cast<CAmount>(100000));
+    assert(MoneyRange(fee));
     const int64_t time = fuzzed_data_provider.ConsumeIntegral<int64_t>();
     const unsigned int entry_height = fuzzed_data_provider.ConsumeIntegral<unsigned int>();
     const bool spends_coinbase = fuzzed_data_provider.ConsumeBool();