lnwallet+sweep: add String method to FeePreference

lnwallet/fee_estimator.go

@@ -54,6 +54,11 @@ func (s SatPerKVByte) FeePerKWeight() SatPerKWeight {
 	return SatPerKWeight(s / blockchain.WitnessScaleFactor)
 }
 
+// String returns a human-readable string of the fee rate.
+func (s SatPerKVByte) String() string {
+	return fmt.Sprintf("%v sat/kb", int64(s))
+}
+
 // SatPerKWeight represents a fee rate in sat/kw.
 type SatPerKWeight btcutil.Amount
 
@@ -69,6 +74,11 @@ func (s SatPerKWeight) FeePerKVByte() SatPerKVByte {
 	return SatPerKVByte(s * blockchain.WitnessScaleFactor)
 }
 
+// String returns a human-readable string of the fee rate.
+func (s SatPerKWeight) String() string {
+	return fmt.Sprintf("%v sat/kw", int64(s))
+}
+
 // FeeEstimator provides the ability to estimate on-chain transaction fees for
 // various combinations of transaction sizes and desired confirmation time
 // (measured by number of blocks).

sweep/walletsweep.go

@@ -30,6 +30,14 @@ type FeePreference struct {
 	FeeRate lnwallet.SatPerKWeight
 }
 
+// String returns a human-readable string of the fee preference.
+func (p FeePreference) String() string {
+	if p.ConfTarget != 0 {
+		return fmt.Sprintf("%v blocks", p.ConfTarget)
+	}
+	return p.FeeRate.String()
+}
+
 // DetermineFeePerKw will determine the fee in sat/kw that should be paid given
 // an estimator, a confirmation target, and a manual value for sat/byte. A
 // value is chosen based on the two free parameters as one, or both of them can