itest: update channel creation itest with Memo field logic

We test both the happy path (valid memo is returned when querying),
as well as the unhappy path (invalid memo rejects the open action).
To accomplish this, we update the OpenChannelParams struct inside
the harness to accept the Memo.

itest/lnd_open_channel_test.go

@@ -2,6 +2,7 @@ package itest
 
 import (
 	"fmt"
+	"strings"
 	"testing"
 
 	"github.com/btcsuite/btcd/btcjson"
@@ -373,16 +374,32 @@ func runBasicChannelCreationAndUpdates(ht *lntest.HarnessTest,
 	aliceChanSub := alice.RPC.SubscribeChannelEvents()
 
 	// Open the channels between Alice and Bob, asserting that the channels
-	// have been properly opened on-chain.
+	// have been properly opened on-chain. We also attach the optional Memo
+	// argument to one of the channels so we can test that it can be
+	// retrieved correctly when querying the created channel.
 	chanPoints := make([]*lnrpc.ChannelPoint, numChannels)
+	openChannelParams := []lntest.OpenChannelParams{
+		{Amt: amount, Memo: "bob is a good peer"},
+		{Amt: amount},
+	}
 	for i := 0; i < numChannels; i++ {
 		chanPoints[i] = ht.OpenChannel(
-			alice, bob, lntest.OpenChannelParams{
-				Amt: amount,
-			},
+			alice, bob, openChannelParams[i],
 		)
 	}
 
+	// Alice should see the memo when retrieving the first channel.
+	channel := ht.QueryChannelByChanPoint(alice, chanPoints[0])
+	require.Equal(ht, "bob is a good peer", channel.Memo)
+
+	// Bob shouldn't see the memo since it's for Alice only.
+	channel = ht.QueryChannelByChanPoint(bob, chanPoints[0])
+	require.Empty(ht, channel.Memo, "Memo is not empty")
+
+	// The second channel doesn't have a memo.
+	channel = ht.QueryChannelByChanPoint(alice, chanPoints[1])
+	require.Empty(ht, channel.Memo, "Memo is not empty")
+
 	// Since each of the channels just became open, Bob and Alice should
 	// each receive an open and an active notification for each channel.
 	const numExpectedOpenUpdates = 3 * numChannels
@@ -445,6 +462,16 @@ func runBasicChannelCreationAndUpdates(ht *lntest.HarnessTest,
 		}
 	}
 
+	// If Bob now tries to open a channel with an invalid memo, reject it.
+	invalidMemo := strings.Repeat("a", 501)
+	params := lntest.OpenChannelParams{
+		Amt:  funding.MaxBtcFundingAmount,
+		Memo: invalidMemo,
+	}
+	expErr := fmt.Errorf("provided memo (%s) is of length 501, exceeds 500",
+		invalidMemo)
+	ht.OpenChannelAssertErr(bob, alice, params, expErr)
+
 	// verifyCloseUpdatesReceived is used to verify that Alice and Bob
 	// receive the correct channel updates in order.
 	const numExpectedCloseUpdates = 3 * numChannels