lnwallet/btcwallet: add compile time check for BlockChainIO interface

contractcourt/channel_arbitrator_test.go

@@ -124,6 +124,8 @@ func (b *mockArbitratorLog) WipeHistory() error {
 
 type mockChainIO struct{}
 
+var _ lnwallet.BlockChainIO = (*mockChainIO)(nil)
+
 func (*mockChainIO) GetBestBlock() (*chainhash.Hash, int32, error) {
 	return nil, 0, nil
 }

lnwallet/btcwallet/btcwallet.go

@@ -67,8 +67,9 @@ type BtcWallet struct {
 }
 
 // A compile time check to ensure that BtcWallet implements the
-// WalletController interface.
+// WalletController and BlockChainIO interfaces.
 var _ lnwallet.WalletController = (*BtcWallet)(nil)
+var _ lnwallet.BlockChainIO = (*BtcWallet)(nil)
 
 // New returns a new fully initialized instance of BtcWallet given a valid
 // configuration struct.

mock.go

@@ -205,6 +205,8 @@ type mockChainIO struct {
 	bestHeight int32
 }
 
+var _ lnwallet.BlockChainIO = (*mockChainIO)(nil)
+
 func (m *mockChainIO) GetBestBlock() (*chainhash.Hash, int32, error) {
 	return activeNetParams.GenesisHash, m.bestHeight, nil
 }

sweep/test_utils.go

@@ -10,6 +10,7 @@ import (
 	"github.com/btcsuite/btcd/wire"
 	"github.com/lightningnetwork/lnd/chainntnfs"
 	"github.com/lightningnetwork/lnd/input"
+	"github.com/lightningnetwork/lnd/lnwallet"
 )
 
 var (
@@ -237,6 +238,8 @@ func (m *MockNotifier) RegisterSpendNtfn(outpoint *wire.OutPoint,
 
 type mockChainIO struct{}
 
+var _ lnwallet.BlockChainIO = (*mockChainIO)(nil)
+
 func (m *mockChainIO) GetBestBlock() (*chainhash.Hash, int32, error) {
 	return nil, mockChainIOHeight, nil
 }