sweep: add unit tests for TestDetermineFeePerKw and CraftSweepAllTx

Along the way we also extend the mockFeeEstimator to be able to return a
fee rate for a specified confirmation target.

sweep/fee_estimator_mock_test.go

@@ -1,8 +1,9 @@
 package sweep
 
 import (
-	"github.com/lightningnetwork/lnd/lnwallet"
 	"sync"
+
+	"github.com/lightningnetwork/lnd/lnwallet"
 )
 
 // mockFeeEstimator implements a mock fee estimator. It closely resembles
@@ -13,6 +14,8 @@ type mockFeeEstimator struct {
 
 	relayFee lnwallet.SatPerKWeight
 
+	blocksToFee map[uint32]lnwallet.SatPerKWeight
+
 	lock sync.Mutex
 }
 
@@ -20,8 +23,9 @@ func newMockFeeEstimator(feePerKW,
 	relayFee lnwallet.SatPerKWeight) *mockFeeEstimator {
 
 	return &mockFeeEstimator{
-		feePerKW: feePerKW,
-		relayFee: relayFee,
+		feePerKW:    feePerKW,
+		relayFee:    relayFee,
+		blocksToFee: make(map[uint32]lnwallet.SatPerKWeight),
 	}
 }
 
@@ -41,6 +45,10 @@ func (e *mockFeeEstimator) EstimateFeePerKW(numBlocks uint32) (
 	e.lock.Lock()
 	defer e.lock.Unlock()
 
+	if fee, ok := e.blocksToFee[numBlocks]; ok {
+		return fee, nil
+	}
+
 	return e.feePerKW, nil
 }
 

sweep/walletsweep.go

@@ -10,6 +10,13 @@ import (
 	"github.com/lightningnetwork/lnd/lnwallet"
 )
 
+const (
+	// defaultNumBlocksEstimate is the number of blocks that we fall back
+	// to issuing an estimate for if a fee pre fence doesn't specify an
+	// explicit conf target or fee rate.
+	defaultNumBlocksEstimate = 6
+)
+
 // FeePreference allows callers to express their time value for inclusion of a
 // transaction into a block via either a confirmation target, or a fee rate.
 type FeePreference struct {
@@ -30,6 +37,12 @@ func DetermineFeePerKw(feeEstimator lnwallet.FeeEstimator,
 	feePref FeePreference) (lnwallet.SatPerKWeight, error) {
 
 	switch {
+	// If both values are set, then we'll return an error as we require a
+	// strict directive.
+	case feePref.FeeRate != 0 && feePref.ConfTarget != 0:
+		return 0, fmt.Errorf("only FeeRate or ConfTarget should " +
+			"be set for FeePreferences")
+
 	// If the target number of confirmations is set, then we'll use that to
 	// consult our fee estimator for an adequate fee.
 	case feePref.ConfTarget != 0:
@@ -61,7 +74,9 @@ func DetermineFeePerKw(feeEstimator lnwallet.FeeEstimator,
 	// Otherwise, we'll attempt a relaxed confirmation target for the
 	// transaction
 	default:
-		feePerKw, err := feeEstimator.EstimateFeePerKW(6)
+		feePerKw, err := feeEstimator.EstimateFeePerKW(
+			defaultNumBlocksEstimate,
+		)
 		if err != nil {
 			return 0, fmt.Errorf("unable to query fee estimator: "+
 				"%v", err)

sweep/walletsweep_test.go

@@ -0,0 +1,409 @@
+package sweep
+
+import (
+	"bytes"
+	"fmt"
+	"testing"
+
+	"github.com/btcsuite/btcd/chaincfg"
+	"github.com/btcsuite/btcd/txscript"
+	"github.com/btcsuite/btcd/wire"
+	"github.com/btcsuite/btcutil"
+	"github.com/lightningnetwork/lnd/lnwallet"
+)
+
+// TestDetermineFeePerKw tests that given a fee preference, the
+// DetermineFeePerKw will properly map it to a concrete fee in sat/kw.
+func TestDetermineFeePerKw(t *testing.T) {
+	t.Parallel()
+
+	defaultFee := lnwallet.SatPerKWeight(999)
+	relayFee := lnwallet.SatPerKWeight(300)
+
+	feeEstimator := newMockFeeEstimator(defaultFee, relayFee)
+
+	// We'll populate two items in the internal map which is used to query
+	// a fee based on a confirmation target: the default conf target, and
+	// an arbitrary conf target. We'll ensure below that both of these are
+	// properly
+	feeEstimator.blocksToFee[50] = 300
+	feeEstimator.blocksToFee[defaultNumBlocksEstimate] = 1000
+
+	testCases := []struct {
+		// feePref is the target fee preference for this case.
+		feePref FeePreference
+
+		// fee is the value the DetermineFeePerKw should return given
+		// the FeePreference above
+		fee lnwallet.SatPerKWeight
+
+		// fail determines if this test case should fail or not.
+		fail bool
+	}{
+		// A fee rate below the fee rate floor should output the floor.
+		{
+			feePref: FeePreference{
+				FeeRate: lnwallet.SatPerKWeight(99),
+			},
+			fee: lnwallet.FeePerKwFloor,
+		},
+
+		// A fee rate above the floor, should pass through and return
+		// the target fee rate.
+		{
+			feePref: FeePreference{
+				FeeRate: 900,
+			},
+			fee: 900,
+		},
+
+		// A specified confirmation target should cause the function to
+		// query the estimator which will return our value specified
+		// above.
+		{
+			feePref: FeePreference{
+				ConfTarget: 50,
+			},
+			fee: 300,
+		},
+
+		// If the caller doesn't specify any values at all, then we
+		// should query for the default conf target.
+		{
+			feePref: FeePreference{},
+			fee:     1000,
+		},
+
+		// Both conf target and fee rate are set, we should return with
+		// an error.
+		{
+			feePref: FeePreference{
+				ConfTarget: 50,
+				FeeRate:    90000,
+			},
+			fee:  300,
+			fail: true,
+		},
+	}
+	for i, testCase := range testCases {
+		targetFee, err := DetermineFeePerKw(
+			feeEstimator, testCase.feePref,
+		)
+		switch {
+		case testCase.fail && err != nil:
+			continue
+
+		case testCase.fail && err == nil:
+			t.Fatalf("expected failure for #%v", i)
+
+		case !testCase.fail && err != nil:
+			t.Fatalf("unable to estimate fee; %v", err)
+		}
+
+		if targetFee != testCase.fee {
+			t.Fatalf("#%v: wrong fee: expected %v got %v", i,
+				testCase.fee, targetFee)
+		}
+	}
+}
+
+type mockUtxoSource struct {
+	outpoints map[wire.OutPoint]*wire.TxOut
+
+	outputs []*lnwallet.Utxo
+}
+
+func newMockUtxoSource(utxos []*lnwallet.Utxo) *mockUtxoSource {
+	m := &mockUtxoSource{
+		outputs:   utxos,
+		outpoints: make(map[wire.OutPoint]*wire.TxOut),
+	}
+
+	for _, utxo := range utxos {
+		m.outpoints[utxo.OutPoint] = &wire.TxOut{
+			Value:    int64(utxo.Value),
+			PkScript: utxo.PkScript,
+		}
+	}
+
+	return m
+}
+
+func (m *mockUtxoSource) ListUnspentWitness(minConfs int32,
+	maxConfs int32) ([]*lnwallet.Utxo, error) {
+
+	return m.outputs, nil
+}
+
+func (m *mockUtxoSource) FetchInputInfo(op *wire.OutPoint) (*wire.TxOut, error) {
+	txOut, ok := m.outpoints[*op]
+	if !ok {
+		return nil, fmt.Errorf("no output found")
+	}
+
+	return txOut, nil
+}
+
+type mockCoinSelectionLocker struct {
+	fail bool
+}
+
+func (m *mockCoinSelectionLocker) WithCoinSelectLock(f func() error) error {
+	if err := f(); err != nil {
+		return err
+	}
+
+	if m.fail {
+		return fmt.Errorf("kek")
+	}
+
+	return nil
+
+}
+
+type mockOutpointLocker struct {
+	lockedOutpoints map[wire.OutPoint]struct{}
+
+	unlockedOutpoints map[wire.OutPoint]struct{}
+}
+
+func newMockOutpointLocker() *mockOutpointLocker {
+	return &mockOutpointLocker{
+		lockedOutpoints: make(map[wire.OutPoint]struct{}),
+
+		unlockedOutpoints: make(map[wire.OutPoint]struct{}),
+	}
+}
+
+func (m *mockOutpointLocker) LockOutpoint(o wire.OutPoint) {
+	m.lockedOutpoints[o] = struct{}{}
+}
+func (m *mockOutpointLocker) UnlockOutpoint(o wire.OutPoint) {
+	m.unlockedOutpoints[o] = struct{}{}
+}
+
+var sweepScript = []byte{
+	0x0, 0x14, 0x64, 0x3d, 0x8b, 0x15, 0x69, 0x4a, 0x54,
+	0x7d, 0x57, 0x33, 0x6e, 0x51, 0xdf, 0xfd, 0x38, 0xe3,
+	0xe, 0x6e, 0xf8, 0xef,
+}
+
+var deliveryAddr = func() btcutil.Address {
+	_, addrs, _, err := txscript.ExtractPkScriptAddrs(
+		sweepScript, &chaincfg.TestNet3Params,
+	)
+	if err != nil {
+		panic(err)
+	}
+
+	return addrs[0]
+}()
+
+var testUtxos = []*lnwallet.Utxo{
+	{
+		// A p2wkh output.
+		PkScript: []byte{
+			0x0, 0x14, 0x64, 0x3d, 0x8b, 0x15, 0x69, 0x4a, 0x54,
+			0x7d, 0x57, 0x33, 0x6e, 0x51, 0xdf, 0xfd, 0x38, 0xe3,
+			0xe, 0x6e, 0xf7, 0xef,
+		},
+		Value: 1000,
+		OutPoint: wire.OutPoint{
+			Index: 1,
+		},
+	},
+
+	{
+		// A np2wkh output.
+		PkScript: []byte{
+			0xa9, 0x14, 0x97, 0x17, 0xf7, 0xd1, 0x5f, 0x6f, 0x8b,
+			0x7, 0xe3, 0x58, 0x43, 0x19, 0xb9, 0x7e, 0xa9, 0x20,
+			0x18, 0xc3, 0x17, 0xd7, 0x87,
+		},
+		Value: 2000,
+		OutPoint: wire.OutPoint{
+			Index: 2,
+		},
+	},
+
+	// A p2wsh output.
+	{
+		PkScript: []byte{
+			0x0, 0x20, 0x70, 0x1a, 0x8d, 0x40, 0x1c, 0x84, 0xfb, 0x13,
+			0xe6, 0xba, 0xf1, 0x69, 0xd5, 0x96, 0x84, 0xe2, 0x7a, 0xbd,
+			0x9f, 0xa2, 0x16, 0xc8, 0xbc, 0x5b, 0x9f, 0xc6, 0x3d, 0x62,
+			0x2f, 0xf8, 0xc5, 0x8c,
+		},
+		Value: 3000,
+		OutPoint: wire.OutPoint{
+			Index: 3,
+		},
+	},
+}
+
+func assertUtxosLocked(t *testing.T, utxoLocker *mockOutpointLocker,
+	utxos []*lnwallet.Utxo) {
+
+	t.Helper()
+
+	for _, utxo := range utxos {
+		if _, ok := utxoLocker.lockedOutpoints[utxo.OutPoint]; !ok {
+			t.Fatalf("utxo %v was never locked", utxo.OutPoint)
+		}
+	}
+
+}
+
+func assertNoUtxosUnlocked(t *testing.T, utxoLocker *mockOutpointLocker,
+	utxos []*lnwallet.Utxo) {
+
+	t.Helper()
+
+	if len(utxoLocker.unlockedOutpoints) != 0 {
+		t.Fatalf("outputs have been locked, but shouldn't have been")
+	}
+}
+
+func assertUtxosUnlocked(t *testing.T, utxoLocker *mockOutpointLocker,
+	utxos []*lnwallet.Utxo) {
+
+	t.Helper()
+
+	for _, utxo := range utxos {
+		if _, ok := utxoLocker.unlockedOutpoints[utxo.OutPoint]; !ok {
+			t.Fatalf("utxo %v was never unlocked", utxo.OutPoint)
+		}
+	}
+}
+
+func assertUtxosLockedAndUnlocked(t *testing.T, utxoLocker *mockOutpointLocker,
+	utxos []*lnwallet.Utxo) {
+
+	t.Helper()
+
+	for _, utxo := range utxos {
+		if _, ok := utxoLocker.lockedOutpoints[utxo.OutPoint]; !ok {
+			t.Fatalf("utxo %v was never locked", utxo.OutPoint)
+		}
+
+		if _, ok := utxoLocker.unlockedOutpoints[utxo.OutPoint]; !ok {
+			t.Fatalf("utxo %v was never unlocked", utxo.OutPoint)
+		}
+	}
+}
+
+// TestCraftSweepAllTxCoinSelectFail tests that if coin selection fails, then
+// we unlock any outputs we may have locked in the passed closure.
+func TestCraftSweepAllTxCoinSelectFail(t *testing.T) {
+	t.Parallel()
+
+	utxoSource := newMockUtxoSource(testUtxos)
+	coinSelectLocker := &mockCoinSelectionLocker{
+		fail: true,
+	}
+	utxoLocker := newMockOutpointLocker()
+
+	_, err := CraftSweepAllTx(
+		0, 100, nil, coinSelectLocker, utxoSource, utxoLocker, nil, nil,
+	)
+
+	// Since we instructed the coin select locker to fail above, we should
+	// get an error.
+	if err == nil {
+		t.Fatalf("sweep tx should have failed: %v", err)
+	}
+
+	// At this point, we'll now verify that all outputs were initially
+	// locked, and then also unlocked due to the failure.
+	assertUtxosLockedAndUnlocked(t, utxoLocker, testUtxos)
+}
+
+// TestCraftSweepAllTxUnknownWitnessType tests that if one of the inputs we
+// encounter is of an unknown witness type, then we fail and unlock any prior
+// locked outputs.
+func TestCraftSweepAllTxUnknownWitnessType(t *testing.T) {
+	t.Parallel()
+
+	utxoSource := newMockUtxoSource(testUtxos)
+	coinSelectLocker := &mockCoinSelectionLocker{}
+	utxoLocker := newMockOutpointLocker()
+
+	_, err := CraftSweepAllTx(
+		0, 100, nil, coinSelectLocker, utxoSource, utxoLocker, nil, nil,
+	)
+
+	// Since passed in a p2wsh output, which is unknown, we should fail to
+	// map the output to a witness type.
+	if err == nil {
+		t.Fatalf("sweep tx should have failed: %v", err)
+	}
+
+	// At this point, we'll now verify that all outputs were initially
+	// locked, and then also unlocked since we weren't able to find a
+	// witness type for the last output.
+	assertUtxosLockedAndUnlocked(t, utxoLocker, testUtxos)
+}
+
+// TestCraftSweepAllTx tests that we'll properly lock all available outputs
+// within the wallet, and craft a single sweep transaction that pays to the
+// target output.
+func TestCraftSweepAllTx(t *testing.T) {
+	t.Parallel()
+
+	// First, we'll make a mock signer along with a fee estimator, We'll
+	// use zero fees to we can assert a precise output value.
+	signer := &mockSigner{}
+	feeEstimator := newMockFeeEstimator(0, 0)
+
+	// For our UTXO source, we'll pass in all the UTXOs that we know of,
+	// other than the final one which is of an unknown witness type.
+	targetUTXOs := testUtxos[:2]
+	utxoSource := newMockUtxoSource(targetUTXOs)
+	coinSelectLocker := &mockCoinSelectionLocker{}
+	utxoLocker := newMockOutpointLocker()
+
+	sweepPkg, err := CraftSweepAllTx(
+		0, 100, deliveryAddr, coinSelectLocker, utxoSource, utxoLocker,
+		feeEstimator, signer,
+	)
+	if err != nil {
+		t.Fatalf("unable to make sweep tx: %v", err)
+	}
+
+	// At this point, all of the UTXOs that we made above should be locked
+	// and none of them unlocked.
+	assertUtxosLocked(t, utxoLocker, testUtxos[:2])
+	assertNoUtxosUnlocked(t, utxoLocker, testUtxos[:2])
+
+	// Now that we have our sweep transaction, we should find that we have
+	// a UTXO for each input, and also that our final output value is the
+	// sum of all our inputs.
+	sweepTx := sweepPkg.SweepTx
+	if len(sweepTx.TxIn) != len(targetUTXOs) {
+		t.Fatalf("expected %v utxo, got %v", len(targetUTXOs),
+			len(sweepTx.TxIn))
+	}
+
+	// We should have a single output that pays to our sweep script
+	// generated above.
+	expectedSweepValue := int64(3000)
+	if len(sweepTx.TxOut) != 1 {
+		t.Fatalf("should have %v outputs, instead have %v", 1,
+			len(sweepTx.TxOut))
+	}
+	output := sweepTx.TxOut[0]
+	switch {
+	case output.Value != expectedSweepValue:
+		t.Fatalf("expected %v sweep value, instead got %v",
+			expectedSweepValue, output.Value)
+
+	case !bytes.Equal(sweepScript, output.PkScript):
+		t.Fatalf("expected %x sweep script, instead got %x", sweepScript,
+			output.PkScript)
+	}
+
+	// If we cancel the sweep attempt, then we should find that all the
+	// UTXOs within the sweep transaction are now unlocked.
+	sweepPkg.CancelSweepAttempt()
+	assertUtxosUnlocked(t, utxoLocker, testUtxos[:2])
+}