feat: Reusability of Mock module for middleware integration tests

testing/README.md

@@ -287,3 +287,19 @@ func GetTransferSimApp(chain *ibctesting.TestChain) *simapp.SimApp {
 	return app
 }
 ```
+
+### Middleware Testing
+
+When writing IBC applications acting as middleware, it might be desirable to test integration points. 
+This can be done by wiring a middleware stack in the app.go file using existing applications as middleware and IBC base applications.
+The mock module may also be leveraged to act as a base application in the instance that such an application is not avaliable for testing or causes dependency concerns. 
+
+The mock module contains a `IBCBaseApp`. This struct contains a function field for every IBC App Module callback. 
+Each of these functions can be individually set to mock expected behaviour of a base application. 
+
+For example, if one wanted to test that the base application cannot affect the outcome of the `OnChanOpenTry` callback, the mock module base application callback could be updated as such:
+```go
+    mockModule.BaseApp.OnChanOpenTry = func(ctx sdk.Context, portID, channelID, version string) error {
+			return fmt.Errorf("mock base app must not be called for OnChanOpenTry")
+	}
+```

testing/mock/ibc_baseapp.go

@@ -0,0 +1,95 @@
+package mock
+
+import (
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	capabilitytypes "github.com/cosmos/cosmos-sdk/x/capability/types"
+
+	channeltypes "github.com/cosmos/ibc-go/v2/modules/core/04-channel/types"
+	"github.com/cosmos/ibc-go/v2/modules/core/exported"
+)
+
+type MockIBCApp struct {
+	OnChanOpenInit func(
+		ctx sdk.Context,
+		order channeltypes.Order,
+		connectionHops []string,
+		portID string,
+		channelID string,
+		channelCap *capabilitytypes.Capability,
+		counterparty channeltypes.Counterparty,
+		version string,
+	) error
+
+	OnChanOpenTry func(
+		ctx sdk.Context,
+		order channeltypes.Order,
+		connectionHops []string,
+		portID,
+		channelID string,
+		channelCap *capabilitytypes.Capability,
+		counterparty channeltypes.Counterparty,
+		version,
+		counterpartyVersion string,
+	) error
+
+	OnChanOpenAck func(
+		ctx sdk.Context,
+		portID,
+		channelID string,
+		counterpartyVersion string,
+	) error
+
+	OnChanOpenConfirm func(
+		ctx sdk.Context,
+		portID,
+		channelID string,
+	) error
+
+	OnChanCloseInit func(
+		ctx sdk.Context,
+		portID,
+		channelID string,
+	) error
+
+	OnChanCloseConfirm func(
+		ctx sdk.Context,
+		portID,
+		channelID string,
+	) error
+
+	// OnRecvPacket must return an acknowledgement that implements the Acknowledgement interface.
+	// In the case of an asynchronous acknowledgement, nil should be returned.
+	// If the acknowledgement returned is successful, the state changes on callback are written,
+	// otherwise the application state changes are discarded. In either case the packet is received
+	// and the acknowledgement is written (in synchronous cases).
+	OnRecvPacket func(
+		ctx sdk.Context,
+		packet channeltypes.Packet,
+		relayer sdk.AccAddress,
+	) exported.Acknowledgement
+
+	OnAcknowledgementPacket func(
+		ctx sdk.Context,
+		packet channeltypes.Packet,
+		acknowledgement []byte,
+		relayer sdk.AccAddress,
+	) error
+
+	OnTimeoutPacket func(
+		ctx sdk.Context,
+		packet channeltypes.Packet,
+		relayer sdk.AccAddress,
+	) error
+
+	// NegotiateAppVersion performs application version negotiation given the provided channel ordering, connectionID, portID, counterparty and proposed version.
+	// An error is returned if version negotiation cannot be performed. For example, an application module implementing this interface
+	// may decide to return an error in the event of the proposed version being incompatible with it's own
+	NegotiateAppVersion func(
+		ctx sdk.Context,
+		order channeltypes.Order,
+		connectionID string,
+		portID string,
+		counterparty channeltypes.Counterparty,
+		proposedVersion string,
+	) (version string, err error)
+}

testing/mock/mock.go

@@ -94,6 +94,7 @@ type AppModule struct {
 	AppModuleBasic
 	scopedKeeper capabilitykeeper.ScopedKeeper
 	portKeeper   PortKeeper
+	BaseApp      MockIBCApp // base application of an IBC middleware stack
 }
 
 // NewAppModule returns a mock AppModule instance.
@@ -153,9 +154,14 @@ func (am AppModule) EndBlock(ctx sdk.Context, req abci.RequestEndBlock) []abci.V
 
 // OnChanOpenInit implements the IBCModule interface.
 func (am AppModule) OnChanOpenInit(
-	ctx sdk.Context, _ channeltypes.Order, _ []string, portID string,
-	channelID string, chanCap *capabilitytypes.Capability, _ channeltypes.Counterparty, _ string,
+	ctx sdk.Context, order channeltypes.Order, connectionHops []string, portID string,
+	channelID string, chanCap *capabilitytypes.Capability, counterparty channeltypes.Counterparty, version string,
 ) error {
+	if am.BaseApp.OnChanOpenInit != nil {
+		return am.BaseApp.OnChanOpenInit(ctx, order, connectionHops, portID, channelID, chanCap, counterparty, version)
+
+	}
+
 	// Claim channel capability passed back by IBC module
 	if err := am.scopedKeeper.ClaimCapability(ctx, chanCap, host.ChannelCapabilityPath(portID, channelID)); err != nil {
 		return err
@@ -166,9 +172,13 @@ func (am AppModule) OnChanOpenInit(
 
 // OnChanOpenTry implements the IBCModule interface.
 func (am AppModule) OnChanOpenTry(
-	ctx sdk.Context, _ channeltypes.Order, _ []string, portID string,
-	channelID string, chanCap *capabilitytypes.Capability, _ channeltypes.Counterparty, _, _ string,
+	ctx sdk.Context, order channeltypes.Order, connectionHops []string, portID string,
+	channelID string, chanCap *capabilitytypes.Capability, counterparty channeltypes.Counterparty, version, counterpartyVersion string,
 ) error {
+	if am.BaseApp.OnChanOpenTry != nil {
+		return am.BaseApp.OnChanOpenTry(ctx, order, connectionHops, portID, channelID, chanCap, counterparty, version, counterpartyVersion)
+
+	}
 	// Claim channel capability passed back by IBC module
 	if err := am.scopedKeeper.ClaimCapability(ctx, chanCap, host.ChannelCapabilityPath(portID, channelID)); err != nil {
 		return err
@@ -178,27 +188,47 @@ func (am AppModule) OnChanOpenTry(
 }
 
 // OnChanOpenAck implements the IBCModule interface.
-func (am AppModule) OnChanOpenAck(sdk.Context, string, string, string) error {
+func (am AppModule) OnChanOpenAck(ctx sdk.Context, portID string, channelID string, counterpartyVersion string) error {
+	if am.BaseApp.OnChanOpenAck != nil {
+		return am.BaseApp.OnChanOpenAck(ctx, portID, channelID, counterpartyVersion)
+	}
+
 	return nil
 }
 
 // OnChanOpenConfirm implements the IBCModule interface.
-func (am AppModule) OnChanOpenConfirm(sdk.Context, string, string) error {
+func (am AppModule) OnChanOpenConfirm(ctx sdk.Context, portID, channelID string) error {
+	if am.BaseApp.OnChanOpenConfirm != nil {
+		return am.BaseApp.OnChanOpenConfirm(ctx, portID, channelID)
+	}
+
 	return nil
 }
 
 // OnChanCloseInit implements the IBCModule interface.
-func (am AppModule) OnChanCloseInit(sdk.Context, string, string) error {
+func (am AppModule) OnChanCloseInit(ctx sdk.Context, portID, channelID string) error {
+	if am.BaseApp.OnChanCloseInit != nil {
+		return am.BaseApp.OnChanCloseInit(ctx, portID, channelID)
+	}
+
 	return nil
 }
 
 // OnChanCloseConfirm implements the IBCModule interface.
-func (am AppModule) OnChanCloseConfirm(sdk.Context, string, string) error {
+func (am AppModule) OnChanCloseConfirm(ctx sdk.Context, portID, channelID string) error {
+	if am.BaseApp.OnChanCloseConfirm != nil {
+		return am.BaseApp.OnChanCloseConfirm(ctx, portID, channelID)
+	}
+
 	return nil
 }
 
 // OnRecvPacket implements the IBCModule interface.
 func (am AppModule) OnRecvPacket(ctx sdk.Context, packet channeltypes.Packet, relayer sdk.AccAddress) exported.Acknowledgement {
+	if am.BaseApp.OnRecvPacket != nil {
+		return am.BaseApp.OnRecvPacket(ctx, packet, relayer)
+	}
+
 	// set state by claiming capability to check if revert happens return
 	_, err := am.scopedKeeper.NewCapability(ctx, MockRecvCanaryCapabilityName+strconv.Itoa(int(packet.GetSequence())))
 	if err != nil {
@@ -216,7 +246,11 @@ func (am AppModule) OnRecvPacket(ctx sdk.Context, packet channeltypes.Packet, re
 }
 
 // OnAcknowledgementPacket implements the IBCModule interface.
-func (am AppModule) OnAcknowledgementPacket(ctx sdk.Context, packet channeltypes.Packet, _ []byte, _ sdk.AccAddress) error {
+func (am AppModule) OnAcknowledgementPacket(ctx sdk.Context, packet channeltypes.Packet, acknowledgement []byte, relayer sdk.AccAddress) error {
+	if am.BaseApp.OnAcknowledgementPacket != nil {
+		return am.BaseApp.OnAcknowledgementPacket(ctx, packet, acknowledgement, relayer)
+	}
+
 	_, err := am.scopedKeeper.NewCapability(ctx, MockAckCanaryCapabilityName+strconv.Itoa(int(packet.GetSequence())))
 	if err != nil {
 		// application callback called twice on same packet sequence
@@ -228,7 +262,11 @@ func (am AppModule) OnAcknowledgementPacket(ctx sdk.Context, packet channeltypes
 }
 
 // OnTimeoutPacket implements the IBCModule interface.
-func (am AppModule) OnTimeoutPacket(ctx sdk.Context, packet channeltypes.Packet, _ sdk.AccAddress) error {
+func (am AppModule) OnTimeoutPacket(ctx sdk.Context, packet channeltypes.Packet, relayer sdk.AccAddress) error {
+	if am.BaseApp.OnTimeoutPacket != nil {
+		return am.BaseApp.OnTimeoutPacket(ctx, packet, relayer)
+	}
+
 	_, err := am.scopedKeeper.NewCapability(ctx, MockTimeoutCanaryCapabilityName+strconv.Itoa(int(packet.GetSequence())))
 	if err != nil {
 		// application callback called twice on same packet sequence
@@ -248,6 +286,10 @@ func (am AppModule) NegotiateAppVersion(
 	counterparty channeltypes.Counterparty,
 	proposedVersion string,
 ) (string, error) {
+	if am.BaseApp.NegotiateAppVersion != nil {
+		return am.BaseApp.NegotiateAppVersion(ctx, order, connectionID, portID, counterparty, proposedVersion)
+	}
+
 	if proposedVersion != Version { // allow testing of error scenarios
 		return "", errors.New("failed to negotiate app version")
 	}

testing/simapp/app.go

@@ -578,6 +578,11 @@ func (app *SimApp) GetScopedIBCKeeper() capabilitykeeper.ScopedKeeper {
 	return app.ScopedIBCKeeper
 }
 
+// GetMockModule returns the mock module in the testing application
+func (app *SimApp) GetMockModule() ibcmock.AppModule {
+	return app.mm.Modules[ibcmock.ModuleName].(ibcmock.AppModule)
+}
+
 // GetTxConfig implements the TestingApp interface.
 func (app *SimApp) GetTxConfig() client.TxConfig {
 	return MakeTestEncodingConfig().TxConfig