added channel invariant check to msg_register_host_zone

x/stakeibc/keeper/msg_server_register_host_zone.go

@@ -57,6 +57,11 @@ func (k msgServer) RegisterHostZone(goCtx context.Context, msg *types.MsgRegiste
 			k.Logger(ctx).Error(errMsg)
 			return nil, errorsmod.Wrapf(types.ErrFailedToRegisterHostZone, errMsg)
 		}
+		if hostZone.TransferChannelId == msg.TransferChannelId {
+			errMsg := fmt.Sprintf("transfer channel %s already registered", msg.TransferChannelId)
+			k.Logger(ctx).Error(errMsg)
+			return nil, errorsmod.Wrapf(types.ErrFailedToRegisterHostZone, errMsg)
+		}
 		if hostZone.Bech32Prefix == msg.Bech32Prefix {
 			errMsg := fmt.Sprintf("bech32prefix %s already registered", msg.Bech32Prefix)
 			k.Logger(ctx).Error(errMsg)

x/stakeibc/keeper/msg_server_register_host_zone_test.go

@@ -237,6 +237,27 @@ func (s *KeeperTestSuite) TestRegisterHostZone_DuplicateHostDenom() {
 	s.Require().EqualError(err, expectedErrMsg, "registering host zone with duplicate host denom should fail")
 }
 
+func (s *KeeperTestSuite) TestRegisterHostZone_DuplicateTransferChannel() {
+	// tests for a failure if we register the same host zone twice (with a duplicate transfer)
+	tc := s.SetupRegisterHostZone()
+
+	// Register host zones successfully
+	_, err := s.GetMsgServer().RegisterHostZone(sdk.WrapSDKContext(s.Ctx), &tc.validMsg)
+	s.Require().NoError(err, "able to successfully register host zone once")
+
+	// Create the message for a brand new host zone
+	// (without modifications, you would expect this to be successful)
+	newHostZoneMsg := s.createNewHostZoneMessage("OSMO", "osmo", "osmo")
+
+	// Try to register with a duplicate transfer channel - it should fail
+	invalidMsg := newHostZoneMsg
+	invalidMsg.TransferChannelId = tc.validMsg.TransferChannelId
+
+	_, err = s.GetMsgServer().RegisterHostZone(sdk.WrapSDKContext(s.Ctx), &invalidMsg)
+	expectedErrMsg := "transfer channel channel-0 already registered: failed to register host zone"
+	s.Require().EqualError(err, expectedErrMsg, "registering host zone with duplicate host denom should fail")
+}
+
 func (s *KeeperTestSuite) TestRegisterHostZone_DuplicateBech32Prefix() {
 	// tests for a failure if we register the same host zone twice (with a duplicate bech32 prefix)
 	tc := s.SetupRegisterHostZone()