add helper function in testing package: RecvPacketWithResult

CHANGELOG.md

@@ -57,6 +57,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### Improvements
 
+* (testing) [\#810](https://github.com/cosmos/ibc-go/pull/810) Additional testing function added to `Endpoint` type called `RecvPacketWithResult`. Performs the same functionality as the existing `RecvPacket` function but also returns the message result. `path.RelayPacket` no longer uses the provided acknowledgement argument and instead obtains the acknowledgement via MsgRecvPacket events.
 * (connection) [\#721](https://github.com/cosmos/ibc-go/pull/721) Simplify connection handshake error messages when unpacking client state.
 * (channel) [\#692](https://github.com/cosmos/ibc-go/pull/692) Minimize channel logging by only emitting the packet sequence, source port/channel, destination port/channel upon packet receives, acknowledgements and timeouts.
 * [\#383](https://github.com/cosmos/ibc-go/pull/383) Adds helper functions for merging and splitting middleware versions from the underlying app version.

testing/endpoint.go

@@ -3,7 +3,7 @@ package ibctesting
 import (
 	"fmt"
 
-	//	sdk "github.com/cosmos/cosmos-sdk/types"
+	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/stretchr/testify/require"
 
 	clienttypes "github.com/cosmos/ibc-go/v3/modules/core/02-client/types"
@@ -375,18 +375,34 @@ func (endpoint *Endpoint) SendPacket(packet exported.PacketI) error {
 // RecvPacket receives a packet on the associated endpoint.
 // The counterparty client is updated.
 func (endpoint *Endpoint) RecvPacket(packet channeltypes.Packet) error {
+	_, err := endpoint.RecvPacketWithResult(packet)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// RecvPacketWithResult receives a packet on the associated endpoint and the result
+// of the transaction is returned. The counterparty client is updated.
+func (endpoint *Endpoint) RecvPacketWithResult(packet channeltypes.Packet) (*sdk.Result, error) {
 	// get proof of packet commitment on source
 	packetKey := host.PacketCommitmentKey(packet.GetSourcePort(), packet.GetSourceChannel(), packet.GetSequence())
 	proof, proofHeight := endpoint.Counterparty.Chain.QueryProof(packetKey)
 
 	recvMsg := channeltypes.NewMsgRecvPacket(packet, proof, proofHeight, endpoint.Chain.SenderAccount.GetAddress().String())
 
 	// receive on counterparty and update source client
-	if err := endpoint.Chain.sendMsgs(recvMsg); err != nil {
-		return err
+	res, err := endpoint.Chain.SendMsgs(recvMsg)
+	if err != nil {
+		return nil, err
 	}
 
-	return endpoint.Counterparty.UpdateClient()
+	if err := endpoint.Counterparty.UpdateClient(); err != nil {
+		return nil, err
+	}
+
+	return res, nil
 }
 
 // WriteAcknowledgement writes an acknowledgement on the channel associated with the endpoint.

testing/events.go

@@ -55,3 +55,18 @@ func ParseChannelIDFromEvents(events sdk.Events) (string, error) {
 	}
 	return "", fmt.Errorf("channel identifier event attribute not found")
 }
+
+// ParseAckFromEvents parses events emitted from a MsgRecvPacket and returns the
+// acknowledgement.
+func ParseAckFromEvents(events sdk.Events) ([]byte, error) {
+	for _, ev := range events {
+		if ev.Type == channeltypes.EventTypeWriteAck {
+			for _, attr := range ev.Attributes {
+				if string(attr.Key) == channeltypes.AttributeKeyAck {
+					return attr.Value, nil
+				}
+			}
+		}
+	}
+	return nil, fmt.Errorf("acknowledgement event attribute not found")
+}

testing/path.go

@@ -38,14 +38,20 @@ func (path *Path) SetChannelOrdered() {
 // RelayPacket attempts to relay the packet first on EndpointA and then on EndpointB
 // if EndpointA does not contain a packet commitment for that packet. An error is returned
 // if a relay step fails or the packet commitment does not exist on either endpoint.
-func (path *Path) RelayPacket(packet channeltypes.Packet, ack []byte) error {
+func (path *Path) RelayPacket(packet channeltypes.Packet, _ []byte) error {
 	pc := path.EndpointA.Chain.App.GetIBCKeeper().ChannelKeeper.GetPacketCommitment(path.EndpointA.Chain.GetContext(), packet.GetSourcePort(), packet.GetSourceChannel(), packet.GetSequence())
 	if bytes.Equal(pc, channeltypes.CommitPacket(path.EndpointA.Chain.App.AppCodec(), packet)) {
 
 		// packet found, relay from A to B
 		path.EndpointB.UpdateClient()
 
-		if err := path.EndpointB.RecvPacket(packet); err != nil {
+		res, err := path.EndpointB.RecvPacketWithResult(packet)
+		if err != nil {
+			return err
+		}
+
+		ack, err := ParseAckFromEvents(res.GetEvents())
+		if err != nil {
 			return err
 		}
 
@@ -62,9 +68,16 @@ func (path *Path) RelayPacket(packet channeltypes.Packet, ack []byte) error {
 		// packet found, relay B to A
 		path.EndpointA.UpdateClient()
 
-		if err := path.EndpointA.RecvPacket(packet); err != nil {
+		res, err := path.EndpointA.RecvPacketWithResult(packet)
+		if err != nil {
 			return err
 		}
+
+		ack, err := ParseAckFromEvents(res.GetEvents())
+		if err != nil {
+			return err
+		}
+
 		if err := path.EndpointB.AcknowledgePacket(packet, ack); err != nil {
 			return err
 		}