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_max_channel_size_test.go

@@ -0,0 +1,67 @@
+//go:build rpctest
+// +build rpctest
+
+package itest
+
+import (
+	"fmt"
+
+	"github.com/btcsuite/btcd/btcutil"
+	"github.com/lightningnetwork/lnd/funding"
+	"github.com/lightningnetwork/lnd/lntemp"
+	"github.com/lightningnetwork/lnd/lnwallet"
+)
+
+// testMaxChannelSize tests that lnd handles --maxchansize parameter correctly.
+// Wumbo nodes should enforce a default soft limit of 10 BTC by default. This
+// limit can be adjusted with --maxchansize config option.
+func testMaxChannelSize(ht *lntemp.HarnessTest) {
+	// We'll make two new nodes, both wumbo but with the default limit on
+	// maximum channel size (10 BTC)
+	wumboNode := ht.NewNode(
+		"wumbo", []string{"--protocol.wumbo-channels"},
+	)
+	wumboNode2 := ht.NewNode(
+		"wumbo2", []string{"--protocol.wumbo-channels"},
+	)
+
+	// We'll send 11 BTC to the wumbo node so it can test the wumbo soft
+	// limit.
+	ht.FundCoins(11*btcutil.SatoshiPerBitcoin, wumboNode)
+
+	// Next we'll connect both nodes, then attempt to make a wumbo channel
+	// funding request, which should fail as it exceeds the default wumbo
+	// soft limit of 10 BTC.
+	ht.EnsureConnected(wumboNode, wumboNode2)
+
+	chanAmt := funding.MaxBtcFundingAmountWumbo + 1
+	// The test should show failure due to the channel exceeding our max
+	// size.
+	expectedErr := lnwallet.ErrChanTooLarge(
+		chanAmt, funding.MaxBtcFundingAmountWumbo,
+	)
+	ht.OpenChannelAssertErr(
+		wumboNode, wumboNode2,
+		lntemp.OpenChannelParams{Amt: chanAmt}, expectedErr,
+	)
+
+	// We'll now make another wumbo node with appropriate maximum channel
+	// size to accept our wumbo channel funding.
+	wumboNode3 := ht.NewNode(
+		"wumbo3", []string{
+			"--protocol.wumbo-channels",
+			fmt.Sprintf(
+				"--maxchansize=%v",
+				int64(funding.MaxBtcFundingAmountWumbo+1),
+			),
+		},
+	)
+
+	// Creating a wumbo channel between these two nodes should succeed.
+	ht.EnsureConnected(wumboNode, wumboNode3)
+	chanPoint := ht.OpenChannel(
+		wumboNode, wumboNode3, lntemp.OpenChannelParams{Amt: chanAmt},
+	)
+
+	ht.CloseChannel(wumboNode, chanPoint)
+}