imp(core): allow huckleberry events with a prefix (#5541)

* feat: initial impl

* imp: moved event helpers to types and added tests

* imp(testing): added mock events to mock module

* test: added msg_server tests for application events

* imp: converted suffix to prefix

* docs: updated inline comments

* imp: review item

* test: review items

* imp: review items

modules/core/keeper/events_test.go

@@ -0,0 +1,106 @@
+package keeper_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	sdk "github.com/cosmos/cosmos-sdk/types"
+
+	"github.com/cosmos/ibc-go/v8/modules/core/keeper"
+	"github.com/cosmos/ibc-go/v8/modules/core/types"
+)
+
+func TestConvertToErrorEvents(t *testing.T) {
+	var (
+		events    sdk.Events
+		expEvents sdk.Events
+	)
+
+	tc := []struct {
+		name     string
+		malleate func()
+	}{
+		{
+			"success: nil events",
+			func() {
+				events = nil
+				expEvents = nil
+			},
+		},
+		{
+			"success: empty events",
+			func() {
+				events = sdk.Events{}
+				expEvents = sdk.Events{}
+			},
+		},
+		{
+			"success: event with no attributes",
+			func() {
+				events = sdk.Events{
+					sdk.NewEvent("testevent"),
+				}
+				expEvents = sdk.Events{
+					sdk.NewEvent(types.ErrorAttributeKeyPrefix + "testevent"),
+				}
+			},
+		},
+		{
+			"success: event with attributes",
+			func() {
+				events = sdk.Events{
+					sdk.NewEvent("testevent",
+						sdk.NewAttribute("key1", "value1"),
+						sdk.NewAttribute("key2", "value2"),
+					),
+				}
+				expEvents = sdk.Events{
+					sdk.NewEvent(types.ErrorAttributeKeyPrefix+"testevent",
+						sdk.NewAttribute(types.ErrorAttributeKeyPrefix+"key1", "value1"),
+						sdk.NewAttribute(types.ErrorAttributeKeyPrefix+"key2", "value2"),
+					),
+				}
+			},
+		},
+		{
+			"success: multiple events with attributes",
+			func() {
+				events = sdk.Events{
+					sdk.NewEvent("testevent1",
+						sdk.NewAttribute("key1", "value1"),
+						sdk.NewAttribute("key2", "value2"),
+					),
+					sdk.NewEvent("testevent2",
+						sdk.NewAttribute("key3", "value3"),
+						sdk.NewAttribute("key4", "value4"),
+					),
+				}
+				expEvents = sdk.Events{
+					sdk.NewEvent(types.ErrorAttributeKeyPrefix+"testevent1",
+						sdk.NewAttribute(types.ErrorAttributeKeyPrefix+"key1", "value1"),
+						sdk.NewAttribute(types.ErrorAttributeKeyPrefix+"key2", "value2"),
+					),
+					sdk.NewEvent(types.ErrorAttributeKeyPrefix+"testevent2",
+						sdk.NewAttribute(types.ErrorAttributeKeyPrefix+"key3", "value3"),
+						sdk.NewAttribute(types.ErrorAttributeKeyPrefix+"key4", "value4"),
+					),
+				}
+			},
+		},
+	}
+
+	for _, tc := range tc {
+		t.Run(tc.name, func(t *testing.T) {
+			// initial events and expected events are reset so that the test fails if
+			// the malleate function does not set them
+			events = nil
+			expEvents = sdk.Events{}
+
+			tc.malleate()
+
+			newEvents := keeper.ConvertToErrorEvents(events)
+			require.Equal(t, expEvents, newEvents)
+		})
+	}
+}

modules/core/keeper/export_test.go

@@ -0,0 +1,9 @@
+package keeper
+
+import sdk "github.com/cosmos/cosmos-sdk/types"
+
+// ConvertToErrorEvents is a wrapper around convertToErrorEvents
+// to allow the function to be directly called in tests.
+func ConvertToErrorEvents(events sdk.Events) sdk.Events {
+	return convertToErrorEvents(events)
+}

modules/core/keeper/msg_server.go

@@ -494,6 +494,9 @@ func (k Keeper) RecvPacket(goCtx context.Context, msg *channeltypes.MsgRecvPacke
 	if ack == nil || ack.Success() {
 		// write application state changes for asynchronous and successful acknowledgements
 		writeFn()
+	} else {
+		// Modify events in cached context to reflect unsuccessful acknowledgement
+		ctx.EventManager().EmitEvents(convertToErrorEvents(cacheCtx.EventManager().Events()))
 	}
 
 	// Set packet acknowledgement only if the acknowledgement is not nil.
@@ -1174,3 +1177,25 @@ func (k Keeper) UpdateChannelParams(goCtx context.Context, msg *channeltypes.Msg
 
 	return &channeltypes.MsgUpdateParamsResponse{}, nil
 }
+
+// convertToErrorEvents converts all events to error events by appending the
+// error attribute prefix to each event's attribute key.
+func convertToErrorEvents(events sdk.Events) sdk.Events {
+	if events == nil {
+		return nil
+	}
+
+	newEvents := make(sdk.Events, len(events))
+	for i, event := range events {
+		newAttributes := make([]sdk.Attribute, len(event.Attributes))
+		for j, attribute := range event.Attributes {
+			newAttributes[j] = sdk.NewAttribute(coretypes.ErrorAttributeKeyPrefix+attribute.Key, attribute.Value)
+		}
+
+		// no need to append the error attribute prefix to the event type because
+		// the event type is not associated to a value that can be misinterpreted
+		newEvents[i] = sdk.NewEvent(coretypes.ErrorAttributeKeyPrefix+event.Type, newAttributes...)
+	}
+
+	return newEvents
+}