Add multiplication operator to CFeeRate

Author: murchandamus

src/policy/feerate.h

@@ -71,6 +71,8 @@ class CFeeRate
     friend bool operator!=(const CFeeRate& a, const CFeeRate& b) { return a.nSatoshisPerK != b.nSatoshisPerK; }
     CFeeRate& operator+=(const CFeeRate& a) { nSatoshisPerK += a.nSatoshisPerK; return *this; }
     std::string ToString(const FeeEstimateMode& fee_estimate_mode = FeeEstimateMode::BTC_KVB) const;
+    friend CFeeRate operator*(const CFeeRate& f, int a) { return CFeeRate(a * f.nSatoshisPerK); }
+    friend CFeeRate operator*(int a, const CFeeRate& f) { return CFeeRate(a * f.nSatoshisPerK); }
 
     SERIALIZE_METHODS(CFeeRate, obj) { READWRITE(obj.nSatoshisPerK); }
 };

src/test/amount_tests.cpp

@@ -85,6 +85,12 @@ BOOST_AUTO_TEST_CASE(GetFeeTest)
     BOOST_CHECK(CFeeRate(CAmount(27), 789) == CFeeRate(34));
     // Maximum size in bytes, should not crash
     CFeeRate(MAX_MONEY, std::numeric_limits<uint32_t>::max()).GetFeePerK();
+
+    // check multiplication operator
+    feeRate = CFeeRate(1000);
+    BOOST_CHECK(0 * feeRate == CFeeRate(0));
+    BOOST_CHECK(3 * feeRate == CFeeRate(3000));
+    BOOST_CHECK(-3 * feeRate == CFeeRate(-3000));
 }
 
 BOOST_AUTO_TEST_CASE(BinaryOperatorTest)