feat: implement OnChanUpgradeAck for transfer

modules/apps/transfer/ibc_module.go

@@ -329,6 +329,10 @@ func (im IBCModule) OnChanUpgradeTry(ctx sdk.Context, portID, channelID string,
 
 // OnChanUpgradeAck implements the IBCModule interface
 func (im IBCModule) OnChanUpgradeAck(ctx sdk.Context, portID, channelID, counterpartyVersion string) error {
+	if counterpartyVersion != types.Version {
+		return errorsmod.Wrapf(types.ErrInvalidVersion, "expected %s, got %s", types.Version, counterpartyVersion)
+	}
+
 	return nil
 }
 

modules/apps/transfer/ibc_module_test.go

@@ -403,3 +403,67 @@ func (suite *TransferTestSuite) TestOnChanUpgradeTry() {
 		})
 	}
 }
+
+func (suite *TransferTestSuite) TestOnChanUpgradeAck() {
+	var path *ibctesting.Path
+
+	testCases := []struct {
+		name     string
+		malleate func()
+		expError error
+	}{
+		{
+			"success",
+			func() {}, // successful happy path for a standalone transfer app is swapping out the underlying connection
+			nil,
+		},
+		{
+			"invalid upgrade version",
+			func() {
+				path.EndpointB.ChannelConfig.Version = "invalid-version"
+			},
+			types.ErrInvalidVersion,
+		},
+	}
+
+	for _, tc := range testCases {
+		tc := tc
+		suite.Run(tc.name, func() {
+			suite.SetupTest()
+
+			path = NewTransferPath(suite.chainA, suite.chainB)
+			suite.coordinator.Setup(path)
+
+			// configure the channel upgrade to modify the underlying connection
+			upgradePath := ibctesting.NewPath(suite.chainA, suite.chainB)
+			suite.coordinator.SetupConnections(upgradePath)
+
+			path.EndpointA.ChannelConfig.ProposedUpgrade.Fields.ConnectionHops = []string{upgradePath.EndpointA.ConnectionID}
+			path.EndpointB.ChannelConfig.ProposedUpgrade.Fields.ConnectionHops = []string{upgradePath.EndpointB.ConnectionID}
+
+			err := path.EndpointA.ChanUpgradeInit()
+			suite.Require().NoError(err)
+
+			err = path.EndpointB.ChanUpgradeTry()
+			suite.Require().NoError(err)
+
+			tc.malleate()
+
+			module, _, err := suite.chainA.App.GetIBCKeeper().PortKeeper.LookupModuleByPort(suite.chainA.GetContext(), types.PortID)
+			suite.Require().NoError(err)
+
+			cbs, ok := suite.chainA.App.GetIBCKeeper().Router.GetRoute(module)
+			suite.Require().True(ok)
+
+			err = cbs.OnChanUpgradeAck(suite.chainA.GetContext(), path.EndpointA.ChannelConfig.PortID, path.EndpointA.ChannelID, path.EndpointB.ChannelConfig.Version)
+
+			expPass := tc.expError == nil
+			if expPass {
+				suite.Require().NoError(err)
+			} else {
+				suite.Require().Error(err)
+				suite.Require().ErrorIs(err, tc.expError)
+			}
+		})
+	}
+}