sweep: create wallet interface

We need access to additional wallet functionality. This commit creates
an interface to prevent passing in multiple function pointers.

server.go

@@ -795,7 +795,7 @@ func newServer(listenAddrs []net.Addr, chanDB *channeldb.DB,
 		FeeEstimator:   cc.feeEstimator,
 		GenSweepScript: newSweepPkScriptGen(cc.wallet),
 		Signer:         cc.wallet.Cfg.Signer,
-		PublishTransaction: cc.wallet.PublishTransaction,
+		Wallet:         cc.wallet,
 		NewBatchTimer: func() <-chan time.Time {
 			return time.NewTimer(sweep.DefaultBatchWindowDuration).C
 		},

sweep/backend_mock_test.go

@@ -2,6 +2,8 @@ package sweep
 
 import (
 	"sync"
+	"testing"
+	"time"
 
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/wire"
@@ -11,6 +13,8 @@ import (
 // mockBackend simulates a chain backend for realistic behaviour in unit tests
 // around double spends.
 type mockBackend struct {
+	t *testing.T
+
 	lock sync.Mutex
 
 	notifier *MockNotifier
@@ -19,14 +23,18 @@ type mockBackend struct {
 
 	unconfirmedTxes        map[chainhash.Hash]*wire.MsgTx
 	unconfirmedSpendInputs map[wire.OutPoint]struct{}
+
+	publishChan chan wire.MsgTx
 }
 
-func newMockBackend(notifier *MockNotifier) *mockBackend {
+func newMockBackend(t *testing.T, notifier *MockNotifier) *mockBackend {
 	return &mockBackend{
+		t:                      t,
 		notifier:               notifier,
 		unconfirmedTxes:        make(map[chainhash.Hash]*wire.MsgTx),
 		confirmedSpendInputs:   make(map[wire.OutPoint]struct{}),
 		unconfirmedSpendInputs: make(map[wire.OutPoint]struct{}),
+		publishChan:            make(chan wire.MsgTx, 2),
 	}
 }
 
@@ -65,6 +73,17 @@ func (b *mockBackend) publishTransaction(tx *wire.MsgTx) error {
 	return nil
 }
 
+func (b *mockBackend) PublishTransaction(tx *wire.MsgTx) error {
+	log.Tracef("Publishing tx %v", tx.TxHash())
+	err := b.publishTransaction(tx)
+	select {
+	case b.publishChan <- *tx:
+	case <-time.After(defaultTestTimeout):
+		b.t.Fatalf("unexpected tx published")
+	}
+	return err
+}
+
 func (b *mockBackend) deleteUnconfirmed(txHash chainhash.Hash) {
 	b.lock.Lock()
 	defer b.lock.Unlock()

sweep/interface.go

@@ -0,0 +1,12 @@
+package sweep
+
+import (
+	"github.com/btcsuite/btcd/wire"
+)
+
+// Wallet contains all wallet related functionality required by sweeper.
+type Wallet interface {
+	// PublishTransaction performs cursory validation (dust checks, etc) and
+	// broadcasts the passed transaction to the Bitcoin network.
+	PublishTransaction(tx *wire.MsgTx) error
+}

sweep/sweeper.go

@@ -210,9 +210,8 @@ type UtxoSweeperConfig struct {
 	// transaction.
 	FeeEstimator chainfee.Estimator
 
-	// PublishTransaction facilitates the process of broadcasting a signed
-	// transaction to the appropriate network.
-	PublishTransaction func(*wire.MsgTx) error
+	// Wallet contains the wallet functions that sweeper requires.
+	Wallet Wallet
 
 	// NewBatchTimer creates a channel that will be sent on when a certain
 	// time window has passed. During this time window, new inputs can still
@@ -321,7 +320,7 @@ func (s *UtxoSweeper) Start() error {
 
 		// Error can be ignored. Because we are starting up, there are
 		// no pending inputs to update based on the publish result.
-		err := s.cfg.PublishTransaction(lastTx)
+		err := s.cfg.Wallet.PublishTransaction(lastTx)
 		if err != nil && err != lnwallet.ErrDoubleSpend {
 			log.Errorf("last tx publish: %v", err)
 		}
@@ -886,7 +885,7 @@ func (s *UtxoSweeper) sweep(inputs inputSet, feeRate chainfee.SatPerKWeight,
 		}),
 	)
 
-	err = s.cfg.PublishTransaction(tx)
+	err = s.cfg.Wallet.PublishTransaction(tx)
 
 	// In case of an unexpected error, don't try to recover.
 	if err != nil && err != lnwallet.ErrDoubleSpend {

sweep/sweeper_test.go

@@ -98,14 +98,13 @@ func createSweeperTestContext(t *testing.T) *sweeperTestContext {
 
 	store := NewMockSweeperStore()
 
-	backend := newMockBackend(notifier)
+	backend := newMockBackend(t, notifier)
 
 	estimator := newMockFeeEstimator(10000, chainfee.FeePerKwFloor)
 
-	publishChan := make(chan wire.MsgTx, 2)
 	ctx := &sweeperTestContext{
 		notifier:    notifier,
-		publishChan: publishChan,
+		publishChan: backend.publishChan,
 		t:           t,
 		estimator:   estimator,
 		backend:     backend,
@@ -116,16 +115,7 @@ func createSweeperTestContext(t *testing.T) *sweeperTestContext {
 	var outputScriptCount byte
 	ctx.sweeper = New(&UtxoSweeperConfig{
 		Notifier: notifier,
-		PublishTransaction: func(tx *wire.MsgTx) error {
-			log.Tracef("Publishing tx %v", tx.TxHash())
-			err := backend.publishTransaction(tx)
-			select {
-			case publishChan <- *tx:
-			case <-time.After(defaultTestTimeout):
-				t.Fatalf("unexpected tx published")
-			}
-			return err
-		},
+		Wallet:   backend,
 		NewBatchTimer: func() <-chan time.Time {
 			c := make(chan time.Time, 1)
 			ctx.timeoutChan <- c