client: fill LastHop in FetchSwaps

Loop used to "forget" last_hop of swaps created before its restart.
The commit fixes this.

Added test TestFetchSwapsLastHop for this. Filled field abandonChans in test
utility function newSwapClient because the field is used in new test.

Fixes https://github.com/lightninglabs/loop/issues/798

client.go

@@ -283,6 +283,7 @@ func (s *Client) FetchSwaps(ctx context.Context) ([]*SwapInfo, error) {
 			SwapStateData: swp.State(),
 			SwapHash:      swp.Hash,
 			LastUpdate:    swp.LastUpdateTime(),
+			LastHop:       swp.Contract.LastHop,
 		}
 
 		htlc, err := utils.GetHtlc(

client_test.go

@@ -16,6 +16,7 @@ import (
 	"github.com/lightninglabs/loop/utils"
 	"github.com/lightningnetwork/lnd/lnrpc"
 	"github.com/lightningnetwork/lnd/lntypes"
+	"github.com/lightningnetwork/lnd/routing/route"
 	"github.com/stretchr/testify/require"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
@@ -45,6 +46,23 @@ var (
 	defaultConfirmations = int32(loopdb.DefaultLoopOutHtlcConfirmations)
 )
 
+var htlcKeys = func() loopdb.HtlcKeys {
+	var senderKey, receiverKey [33]byte
+
+	// Generate keys.
+	_, senderPubKey := test.CreateKey(1)
+	copy(senderKey[:], senderPubKey.SerializeCompressed())
+	_, receiverPubKey := test.CreateKey(2)
+	copy(receiverKey[:], receiverPubKey.SerializeCompressed())
+
+	return loopdb.HtlcKeys{
+		SenderScriptKey:        senderKey,
+		ReceiverScriptKey:      receiverKey,
+		SenderInternalPubKey:   senderKey,
+		ReceiverInternalPubKey: receiverKey,
+	}
+}()
+
 // TestLoopOutSuccess tests the loop out happy flow, using a custom htlc
 // confirmation target.
 func TestLoopOutSuccess(t *testing.T) {
@@ -437,3 +455,59 @@ func TestWrapGrpcError(t *testing.T) {
 		})
 	}
 }
+
+// TestFetchSwapsLastHop asserts that FetchSwaps loads LastHop for LoopIn's.
+func TestFetchSwapsLastHop(t *testing.T) {
+	defer test.Guard(t)()
+
+	ctx := createClientTestContext(t, nil)
+
+	lastHop := route.Vertex{1, 2, 3}
+
+	// Create a loop in swap.
+	swapHash := lntypes.Hash{1, 1, 1}
+	swap := &loopdb.LoopInContract{
+		SwapContract: loopdb.SwapContract{
+			CltvExpiry:      111,
+			AmountRequested: 111,
+			ProtocolVersion: loopdb.ProtocolVersionMuSig2,
+			HtlcKeys:        htlcKeys,
+		},
+		LastHop: &lastHop,
+	}
+	err := ctx.store.CreateLoopIn(context.Background(), swapHash, swap)
+	require.NoError(t, err, "CreateLoopOut failed")
+
+	// Now read all the swaps from the store
+	swapInfos, err := ctx.swapClient.FetchSwaps(context.Background())
+	require.NoError(t, err, "FetchSwaps failed")
+
+	// Find the loop-in and compare with the expected value.
+	require.Len(t, swapInfos, 1)
+	loopInInfo := swapInfos[0]
+	wantLoopInInfo := &SwapInfo{
+		SwapHash: swapHash,
+		SwapContract: loopdb.SwapContract{
+			CltvExpiry:      111,
+			AmountRequested: 111,
+			ProtocolVersion: loopdb.ProtocolVersionMuSig2,
+			HtlcKeys:        htlcKeys,
+		},
+
+		// Make sure LastHop is filled.
+		LastHop: &lastHop,
+	}
+
+	// Calculate HtlcAddressP2TR.
+	htlc, err := utils.GetHtlc(
+		swapHash, &wantLoopInInfo.SwapContract,
+		&chaincfg.TestNet3Params,
+	)
+	require.NoError(t, err)
+	wantLoopInInfo.HtlcAddressP2TR = htlc.Address
+
+	require.Equal(t, wantLoopInInfo, loopInInfo)
+
+	// Shutdown the client not to leak goroutines.
+	ctx.finish()
+}

testcontext_test.go

@@ -108,6 +108,7 @@ func newSwapClient(t *testing.T, config *clientConfig) *Client {
 		sweeper:      sweeper,
 		executor:     executor,
 		resumeReady:  make(chan struct{}),
+		abandonChans: make(map[lntypes.Hash]chan struct{}),
 	}
 }