lnwallet+mock: add new PSBT methods

lntest/mock/walletcontroller.go

@@ -10,6 +10,7 @@ import (
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/btcsuite/btcutil"
+	"github.com/btcsuite/btcutil/psbt"
 	"github.com/btcsuite/btcwallet/wallet/txauthor"
 	"github.com/btcsuite/btcwallet/wtxmgr"
 
@@ -141,6 +142,18 @@ func (w *WalletController) ReleaseOutput(wtxmgr.LockID, wire.OutPoint) error {
 	return nil
 }
 
+// FundPsbt currently does nothing.
+func (w *WalletController) FundPsbt(_ *psbt.Packet,
+	_ chainfee.SatPerKWeight) (int32, error) {
+
+	return 0, nil
+}
+
+// FinalizePsbt currently does nothing.
+func (w *WalletController) FinalizePsbt(_ *psbt.Packet) error {
+	return nil
+}
+
 // PublishTransaction sends a transaction to the PublishedTransactions chan.
 func (w *WalletController) PublishTransaction(tx *wire.MsgTx, _ string) error {
 	w.PublishedTransactions <- tx