diff --git a/routing/mock_test.go b/routing/mock_test.go
index 2458f538b..f712c420d 100644
--- a/routing/mock_test.go
+++ b/routing/mock_test.go
@@ -12,7 +12,9 @@ import (
 	"github.com/lightningnetwork/lnd/htlcswitch"
 	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/lnwire"
+	"github.com/lightningnetwork/lnd/record"
 	"github.com/lightningnetwork/lnd/routing/route"
+	"github.com/lightningnetwork/lnd/routing/shards"
 	"github.com/stretchr/testify/mock"
 )
 
@@ -572,8 +574,6 @@ func (m *mockControlTowerOld) SubscribeAllPayments() (
 
 type mockPaymentAttemptDispatcher struct {
 	mock.Mock
-
-	resultChan chan *htlcswitch.PaymentResult
 }
 
 var _ PaymentAttemptDispatcher = (*mockPaymentAttemptDispatcher)(nil)
@@ -589,11 +589,14 @@ func (m *mockPaymentAttemptDispatcher) GetAttemptResult(attemptID uint64,
 	paymentHash lntypes.Hash, deobfuscator htlcswitch.ErrorDecrypter) (
 	<-chan *htlcswitch.PaymentResult, error) {
 
-	m.Called(attemptID, paymentHash, deobfuscator)
+	args := m.Called(attemptID, paymentHash, deobfuscator)
 
-	// Instead of returning the mocked returned values, we need to return
-	// the chan resultChan so it can be converted into a read-only chan.
-	return m.resultChan, nil
+	resultChan := args.Get(0)
+	if resultChan == nil {
+		return nil, args.Error(1)
+	}
+
+	return args.Get(0).(chan *htlcswitch.PaymentResult), args.Error(1)
 }
 
 func (m *mockPaymentAttemptDispatcher) CleanStore(
@@ -698,7 +701,6 @@ func (m *mockPaymentSession) GetAdditionalEdgePolicy(pubKey *btcec.PublicKey,
 
 type mockControlTower struct {
 	mock.Mock
-	sync.Mutex
 }
 
 var _ ControlTower = (*mockControlTower)(nil)
@@ -718,9 +720,6 @@ func (m *mockControlTower) DeleteFailedAttempts(phash lntypes.Hash) error {
 func (m *mockControlTower) RegisterAttempt(phash lntypes.Hash,
 	a *channeldb.HTLCAttemptInfo) error {
 
-	m.Lock()
-	defer m.Unlock()
-
 	args := m.Called(phash, a)
 	return args.Error(0)
 }
@@ -729,29 +728,32 @@ func (m *mockControlTower) SettleAttempt(phash lntypes.Hash,
 	pid uint64, settleInfo *channeldb.HTLCSettleInfo) (
 	*channeldb.HTLCAttempt, error) {
 
-	m.Lock()
-	defer m.Unlock()
-
 	args := m.Called(phash, pid, settleInfo)
-	return args.Get(0).(*channeldb.HTLCAttempt), args.Error(1)
+
+	attempt := args.Get(0)
+	if attempt == nil {
+		return nil, args.Error(1)
+	}
+
+	return attempt.(*channeldb.HTLCAttempt), args.Error(1)
 }
 
 func (m *mockControlTower) FailAttempt(phash lntypes.Hash, pid uint64,
 	failInfo *channeldb.HTLCFailInfo) (*channeldb.HTLCAttempt, error) {
 
-	m.Lock()
-	defer m.Unlock()
-
 	args := m.Called(phash, pid, failInfo)
+
+	attempt := args.Get(0)
+	if attempt == nil {
+		return nil, args.Error(1)
+	}
+
 	return args.Get(0).(*channeldb.HTLCAttempt), args.Error(1)
 }
 
 func (m *mockControlTower) FailPayment(phash lntypes.Hash,
 	reason channeldb.FailureReason) error {
 
-	m.Lock()
-	defer m.Unlock()
-
 	args := m.Called(phash, reason)
 	return args.Error(0)
 }
@@ -877,3 +879,70 @@ func (m *mockLink) EligibleToForward() bool {
 func (m *mockLink) MayAddOutgoingHtlc(_ lnwire.MilliSatoshi) error {
 	return m.mayAddOutgoingErr
 }
+
+type mockShardTracker struct {
+	mock.Mock
+}
+
+var _ shards.ShardTracker = (*mockShardTracker)(nil)
+
+func (m *mockShardTracker) NewShard(attemptID uint64,
+	lastShard bool) (shards.PaymentShard, error) {
+
+	args := m.Called(attemptID, lastShard)
+
+	shard := args.Get(0)
+	if shard == nil {
+		return nil, args.Error(1)
+	}
+
+	return shard.(shards.PaymentShard), args.Error(1)
+}
+
+func (m *mockShardTracker) GetHash(attemptID uint64) (lntypes.Hash, error) {
+	args := m.Called(attemptID)
+	return args.Get(0).(lntypes.Hash), args.Error(1)
+}
+
+func (m *mockShardTracker) CancelShard(attemptID uint64) error {
+	args := m.Called(attemptID)
+	return args.Error(0)
+}
+
+type mockShard struct {
+	mock.Mock
+}
+
+var _ shards.PaymentShard = (*mockShard)(nil)
+
+// Hash returns the hash used for the HTLC representing this shard.
+func (m *mockShard) Hash() lntypes.Hash {
+	args := m.Called()
+	return args.Get(0).(lntypes.Hash)
+}
+
+// MPP returns any extra MPP records that should be set for the final
+// hop on the route used by this shard.
+func (m *mockShard) MPP() *record.MPP {
+	args := m.Called()
+
+	r := args.Get(0)
+	if r == nil {
+		return nil
+	}
+
+	return r.(*record.MPP)
+}
+
+// AMP returns any extra AMP records that should be set for the final
+// hop on the route used by this shard.
+func (m *mockShard) AMP() *record.AMP {
+	args := m.Called()
+
+	r := args.Get(0)
+	if r == nil {
+		return nil
+	}
+
+	return r.(*record.AMP)
+}
diff --git a/routing/router_test.go b/routing/router_test.go
index 79f0b026c..3f1f5dcb1 100644
--- a/routing/router_test.go
+++ b/routing/router_test.go
@@ -3528,12 +3528,12 @@ func TestSendToRouteSkipTempErrSuccess(t *testing.T) {
 	).Return(nil)
 
 	// Create a buffered chan and it will be returned by GetAttemptResult.
-	payer.resultChan = make(chan *htlcswitch.PaymentResult, 1)
+	resultChan := make(chan *htlcswitch.PaymentResult, 1)
 	payer.On("GetAttemptResult",
 		mock.Anything, mock.Anything, mock.Anything,
-	).Run(func(_ mock.Arguments) {
+	).Return(resultChan, nil).Run(func(_ mock.Arguments) {
 		// Send a successful payment result.
-		payer.resultChan <- &htlcswitch.PaymentResult{}
+		resultChan <- &htlcswitch.PaymentResult{}
 	})
 
 	missionControl.On("ReportPaymentSuccess",
@@ -3599,6 +3599,11 @@ func TestSendToRouteSkipTempErrTempFailure(t *testing.T) {
 		},
 	}}
 
+	// Create the error to be returned.
+	tempErr := htlcswitch.NewForwardingError(
+		&lnwire.FailTemporaryChannelFailure{}, 1,
+	)
+
 	// Register mockers with the expected method calls.
 	controlTower.On("InitPayment", payHash, mock.Anything).Return(nil)
 	controlTower.On("RegisterAttempt", payHash, mock.Anything).Return(nil)
@@ -3608,26 +3613,7 @@ func TestSendToRouteSkipTempErrTempFailure(t *testing.T) {
 
 	payer.On("SendHTLC",
 		mock.Anything, mock.Anything, mock.Anything,
-	).Return(nil)
-
-	// Create a buffered chan and it will be returned by GetAttemptResult.
-	payer.resultChan = make(chan *htlcswitch.PaymentResult, 1)
-
-	// Create the error to be returned.
-	tempErr := htlcswitch.NewForwardingError(
-		&lnwire.FailTemporaryChannelFailure{},
-		1,
-	)
-
-	// Mock GetAttemptResult to return a failure.
-	payer.On("GetAttemptResult",
-		mock.Anything, mock.Anything, mock.Anything,
-	).Run(func(_ mock.Arguments) {
-		// Send an attempt failure.
-		payer.resultChan <- &htlcswitch.PaymentResult{
-			Error: tempErr,
-		}
-	})
+	).Return(tempErr)
 
 	// Mock the control tower to return the mocked payment.
 	payment := &mockMPPayment{}