Set effective_value when initializing a COutput

Previously in COutput, effective_value was initialized as the absolute
value of the txout, and fee as 0. effective_value along with fee were
calculated outside of the COutput constructor and set after the
object had been initialized. These changes will allow either the fee
or the feerate to be passed in a COutput constructor. If either are
provided, fee and effective_value are calculated and set in the
constructor. As a result, AvailableCoins also needs to be passed the
feerate when utxos are being spent. When balance is calculated or the
coins are being listed and feerate is neither available nor required,
AvailableCoinsListUnspent is used instead, which runs AvailableCoins
while providing the default value for feerate. Unit tests for the
calculation of effective value have also been added.

src/wallet/coinselection.h

@@ -20,6 +20,14 @@ static constexpr CAmount CHANGE_UPPER{1000000};
 
 /** A UTXO under consideration for use in funding a new transaction. */
 struct COutput {
+private:
+    /** The output's value minus fees required to spend it.*/
+    std::optional<CAmount> effective_value;
+
+    /** The fee required to spend this output at the transaction's target feerate. */
+    std::optional<CAmount> fee;
+
+public:
     /** The outpoint identifying this UTXO */
     COutPoint outpoint;
 
@@ -55,16 +63,10 @@ struct COutput {
     /** Whether the transaction containing this output is sent from the owning wallet */
     bool from_me;
 
-    /** The output's value minus fees required to spend it. Initialized as the output's absolute value. */
-    CAmount effective_value;
-
-    /** The fee required to spend this output at the transaction's target feerate. */
-    CAmount fee{0};
-
     /** The fee required to spend this output at the consolidation feerate. */
     CAmount long_term_fee{0};
 
-    COutput(const COutPoint& outpoint, const CTxOut& txout, int depth, int input_bytes, bool spendable, bool solvable, bool safe, int64_t time, bool from_me)
+    COutput(const COutPoint& outpoint, const CTxOut& txout, int depth, int input_bytes, bool spendable, bool solvable, bool safe, int64_t time, bool from_me, const std::optional<CFeeRate> feerate = std::nullopt)
         : outpoint{outpoint},
           txout{txout},
           depth{depth},
@@ -73,9 +75,22 @@ struct COutput {
           solvable{solvable},
           safe{safe},
           time{time},
-          from_me{from_me},
-          effective_value{txout.nValue}
-    {}
+          from_me{from_me}
+    {
+        if (feerate) {
+            fee = input_bytes < 0 ? 0 : feerate.value().GetFee(input_bytes);
+            effective_value = txout.nValue - fee.value();
+        }
+    }
+
+    COutput(const COutPoint& outpoint, const CTxOut& txout, int depth, int input_bytes, bool spendable, bool solvable, bool safe, int64_t time, bool from_me, const CAmount fees)
+        : COutput(outpoint, txout, depth, input_bytes, spendable, solvable, safe, time, from_me)
+    {
+        // if input_bytes is unknown, then fees should be 0, if input_bytes is known, then the fees should be a positive integer or 0 (input_bytes known and fees = 0 only happens in the tests)
+        assert((input_bytes < 0 && fees == 0) || (input_bytes > 0 && fees >= 0));
+        fee = fees;
+        effective_value = txout.nValue - fee.value();
+    }
 
     std::string ToString() const;
 
@@ -83,6 +98,18 @@ struct COutput {
     {
         return outpoint < rhs.outpoint;
     }
+
+    CAmount GetFee() const
+    {
+        assert(fee.has_value());
+        return fee.value();
+    }
+
+    CAmount GetEffectiveValue() const
+    {
+        assert(effective_value.has_value());
+        return effective_value.value();
+    }
 };
 
 /** Parameters for one iteration of Coin Selection. */