channeldb+kvdb: add walletdb interface test

This commit adds walletdb interface test suite to the existing test set.

channeldb/kvdb/etcd/walletdb_interface_test.go

@@ -0,0 +1,15 @@
+package etcd
+
+import (
+	"testing"
+
+	"github.com/btcsuite/btcwallet/walletdb/walletdbtest"
+)
+
+// TestWalletDBInterface performs the WalletDB interface test suite for the
+// etcd database driver.
+func TestWalletDBInterface(t *testing.T) {
+	f := NewEtcdTestFixture(t)
+	defer f.Cleanup()
+	walletdbtest.TestInterface(t, dbType, f.BackendConfig())
+}