multi: move itest out of lntest

This commit moves all the test cases living in `itest` out of `lntest`,
further making `lntest` an independent package for general testing.

itest/lnd_wipe_fwdpkgs_test.go

@@ -0,0 +1,124 @@
+package itest
+
+import (
+	"time"
+
+	"github.com/lightningnetwork/lnd/chainreg"
+	"github.com/lightningnetwork/lnd/lnrpc"
+	"github.com/lightningnetwork/lnd/lntemp"
+	"github.com/stretchr/testify/require"
+)
+
+type pendingChan *lnrpc.PendingChannelsResponse_PendingChannel
+
+// testWipeForwardingPackagesLocal tests that when a channel is closed, either
+// through local force close, remote close, or coop close, all the forwarding
+// packages of that particular channel are deleted. The test creates a
+// topology as Alice -> Bob -> Carol, and sends payments from Alice to Carol
+// through Bob. It then performs the test in two steps,
+//   - Bob force closes the channel Alice->Bob, and checks from both Bob's
+//     PoV(local force close) and Alice's Pov(remote close) that the forwarding
+//     packages are wiped.
+//   - Bob coop closes the channel Bob->Carol, and checks from both Bob PoVs
+//     that the forwarding packages are wiped.
+func testWipeForwardingPackages(ht *lntemp.HarnessTest) {
+	const (
+		chanAmt        = 10e6
+		paymentAmt     = 10e4
+		finalCTLVDelta = chainreg.DefaultBitcoinTimeLockDelta
+		numInvoices    = 3
+	)
+
+	// Grab Alice and Bob from HarnessTest.
+	alice, bob := ht.Alice, ht.Bob
+
+	// Create a new node Carol, which will create invoices that require
+	// Alice to pay.
+	carol := ht.NewNode("Carol", nil)
+
+	// Connect Bob to Carol.
+	ht.ConnectNodes(bob, carol)
+
+	// Open a channel between Alice and Bob.
+	chanPointAB := ht.OpenChannel(
+		alice, bob, lntemp.OpenChannelParams{Amt: chanAmt},
+	)
+
+	// Open a channel between Bob and Carol.
+	chanPointBC := ht.OpenChannel(
+		bob, carol, lntemp.OpenChannelParams{Amt: chanAmt},
+	)
+
+	// Before we continue, make sure Alice has seen the channel between Bob
+	// and Carol.
+	ht.AssertTopologyChannelOpen(alice, chanPointBC)
+
+	// Alice sends several payments to Carol through Bob, which triggers
+	// Bob to create forwarding packages.
+	for i := 0; i < numInvoices; i++ {
+		// Add an invoice for Carol.
+		invoice := &lnrpc.Invoice{Memo: "testing", Value: paymentAmt}
+		resp := carol.RPC.AddInvoice(invoice)
+
+		// Alice sends a payment to Carol through Bob.
+		ht.CompletePaymentRequests(alice, []string{resp.PaymentRequest})
+	}
+
+	// TODO(yy): remove the sleep once the following bug is fixed.
+	// When the invoice is reported settled, the commitment dance is not
+	// yet finished, which can cause an error when closing the channel,
+	// saying there's active HTLCs. We need to investigate this issue and
+	// reverse the order to, first finish the commitment dance, then report
+	// the invoice as settled.
+	time.Sleep(2 * time.Second)
+
+	// Firstly, Bob force closes the channel.
+	ht.CloseChannelAssertPending(bob, chanPointAB, true)
+
+	// Now that the channel has been force closed, it should show up in
+	// bob's PendingChannels RPC under the waiting close section.
+	pendingAB := ht.AssertChannelWaitingClose(bob, chanPointAB).Channel
+
+	// Check that Bob has created forwarding packages. We don't care the
+	// exact number here as long as these packages are deleted when the
+	// channel is closed.
+	require.NotZero(ht, pendingAB.NumForwardingPackages)
+
+	// Secondly, Bob coop closes the channel.
+	ht.CloseChannelAssertPending(bob, chanPointBC, false)
+
+	// Now that the channel has been coop closed, it should show up in
+	// bob's PendingChannels RPC under the waiting close section.
+	pendingBC := ht.AssertChannelWaitingClose(bob, chanPointBC).Channel
+
+	// Check that Bob has created forwarding packages. We don't care the
+	// exact number here as long as these packages are deleted when the
+	// channel is closed.
+	require.NotZero(ht, pendingBC.NumForwardingPackages)
+
+	// Since it's a coop close, Carol should see the waiting close channel
+	// too.
+	pendingBC = ht.AssertChannelWaitingClose(carol, chanPointBC).Channel
+	require.NotZero(ht, pendingBC.NumForwardingPackages)
+
+	// Mine 1 block to get the two closing transactions confirmed.
+	ht.MineBlocksAndAssertNumTxes(1, 2)
+
+	// Now that the closing transaction is confirmed, the above waiting
+	// close channel should now become pending force closed channel.
+	pendingAB = ht.AssertChannelPendingForceClose(bob, chanPointAB).Channel
+
+	// Check the forwarding pacakges are deleted.
+	require.Zero(ht, pendingAB.NumForwardingPackages)
+
+	// For Alice, the forwarding packages should have been wiped too.
+	pending := ht.AssertChannelPendingForceClose(alice, chanPointAB)
+	pendingAB = pending.Channel
+	require.Zero(ht, pendingAB.NumForwardingPackages)
+
+	// Mine 1 block to get Alice's sweeping tx confirmed.
+	ht.MineBlocksAndAssertNumTxes(1, 1)
+
+	// Clean up the force closed channel.
+	ht.CleanupForceClose(bob, chanPointAB)
+}