itest: add custom channel integration test

Author: guggero

go.mod

@@ -7,6 +7,7 @@ require (
 	github.com/btcsuite/btcd/chaincfg/chainhash v1.1.0
 	github.com/btcsuite/btclog v0.0.0-20170628155309-84c8d2346e9f
 	github.com/btcsuite/btcwallet/walletdb v1.4.2
+	github.com/davecgh/go-spew v1.1.1
 	github.com/go-errors/errors v1.0.1
 	github.com/grpc-ecosystem/grpc-gateway/v2 v2.16.0
 	github.com/improbable-eng/grpc-web v0.12.0
@@ -69,7 +70,6 @@ require (
 	github.com/coreos/go-systemd v0.0.0-20191104093116-d3cd4ed1dbcf // indirect
 	github.com/coreos/go-systemd/v22 v22.3.2 // indirect
 	github.com/cpuguy83/go-md2man/v2 v2.0.0 // indirect
-	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/decred/dcrd/crypto/blake256 v1.0.1 // indirect
 	github.com/decred/dcrd/dcrec/secp256k1/v4 v4.3.0 // indirect
 	github.com/decred/dcrd/lru v1.1.2 // indirect

itest/assertions.go

@@ -172,9 +172,11 @@ func assertChannelClosed(ctx context.Context, t *harnessTest,
 	// block.
 	block := mineBlocks(t, net, 1, 1)[0]
 
-	closingTxid, err := net.WaitForChannelClose(closeUpdates)
+	closingUpdate, err := net.WaitForChannelClose(closeUpdates)
 	require.NoError(t.t, err, "error while waiting for channel close")
 
+	closingTxid, err := chainhash.NewHash(closingUpdate.ClosingTxid)
+	require.NoError(t.t, err)
 	assertTxInBlock(t, block, closingTxid)
 
 	// Finally, the transaction should no longer be in the waiting close