chore: add ParsePacketFromEvents testing helper function (#904)

## Description

ref: #891

---

Before we can merge this PR, please make sure that all the following items have been
checked off. If any of the checklist items are not applicable, please leave them but
write a little note why.

- [ ] Targeted PR against correct branch (see [CONTRIBUTING.md](https://github.com/cosmos/ibc-go/blob/master/CONTRIBUTING.md#pr-targeting))
- [ ] Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
- [ ] Code follows the [module structure standards](https://github.com/cosmos/cosmos-sdk/blob/master/docs/building-modules/structure.md).
- [ ] Wrote unit and integration [tests](https://github.com/cosmos/ibc-go/blob/master/CONTRIBUTING.md#testing)
- [ ] Updated relevant documentation (`docs/`) or specification (`x/<module>/spec/`)
- [ ] Added relevant `godoc` [comments](https://blog.golang.org/godoc-documenting-go-code).
- [ ] Added a relevant changelog entry to the `Unreleased` section in `CHANGELOG.md`
- [ ] Re-reviewed `Files changed` in the Github PR explorer
- [ ] Review `Codecov Report` in the comment section below once CI passes

(cherry picked from commit c27d5b5)

CHANGELOG.md

@@ -61,6 +61,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### Improvements
 
+* (testing) [\#904](https://github.com/cosmos/ibc-go/pull/904) Add `ParsePacketFromEvents` function to the testing package. Useful when sending/relaying packets via the testing package.
 * (testing) [\#893](https://github.com/cosmos/ibc-go/pull/893) Support custom private keys for testing.
 * (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.

modules/apps/transfer/keeper/relay_test.go

@@ -186,12 +186,12 @@ func (suite *KeeperTestSuite) TestOnRecvPacket() {
 				// send coin from chainB to chainA, receive them, acknowledge them, and send back to chainB
 				coinFromBToA := sdk.NewCoin(sdk.DefaultBondDenom, sdk.NewInt(100))
 				transferMsg := types.NewMsgTransfer(path.EndpointB.ChannelConfig.PortID, path.EndpointB.ChannelID, coinFromBToA, suite.chainB.SenderAccount.GetAddress().String(), suite.chainA.SenderAccount.GetAddress().String(), clienttypes.NewHeight(0, 110), 0)
-				_, err := suite.chainB.SendMsgs(transferMsg)
+				res, err := suite.chainB.SendMsgs(transferMsg)
 				suite.Require().NoError(err) // message committed
 
-				// relay send packet
-				fungibleTokenPacket := types.NewFungibleTokenPacketData(coinFromBToA.Denom, coinFromBToA.Amount.String(), suite.chainB.SenderAccount.GetAddress().String(), suite.chainA.SenderAccount.GetAddress().String())
-				packet := channeltypes.NewPacket(fungibleTokenPacket.GetBytes(), 1, path.EndpointB.ChannelConfig.PortID, path.EndpointB.ChannelID, path.EndpointA.ChannelConfig.PortID, path.EndpointA.ChannelID, clienttypes.NewHeight(0, 110), 0)
+				packet, err := ibctesting.ParsePacketFromEvents(res.GetEvents())
+				suite.Require().NoError(err)
+
 				err = path.RelayPacket(packet)
 				suite.Require().NoError(err) // relay committed
 

modules/apps/transfer/transfer_test.go

@@ -8,7 +8,6 @@ import (
 
 	"github.com/cosmos/ibc-go/v3/modules/apps/transfer/types"
 	clienttypes "github.com/cosmos/ibc-go/v3/modules/core/02-client/types"
-	channeltypes "github.com/cosmos/ibc-go/v3/modules/core/04-channel/types"
 	ibctesting "github.com/cosmos/ibc-go/v3/testing"
 )
 
@@ -56,13 +55,13 @@ func (suite *TransferTestSuite) TestHandleMsgTransfer() {
 
 	// send from chainA to chainB
 	msg := types.NewMsgTransfer(path.EndpointA.ChannelConfig.PortID, path.EndpointA.ChannelID, coinToSendToB, suite.chainA.SenderAccount.GetAddress().String(), suite.chainB.SenderAccount.GetAddress().String(), timeoutHeight, 0)
-
-	_, err := suite.chainA.SendMsgs(msg)
+	res, err := suite.chainA.SendMsgs(msg)
 	suite.Require().NoError(err) // message committed
 
+	packet, err := ibctesting.ParsePacketFromEvents(res.GetEvents())
+	suite.Require().NoError(err)
+
 	// relay send
-	fungibleTokenPacket := types.NewFungibleTokenPacketData(coinToSendToB.Denom, coinToSendToB.Amount.String(), suite.chainA.SenderAccount.GetAddress().String(), suite.chainB.SenderAccount.GetAddress().String())
-	packet := channeltypes.NewPacket(fungibleTokenPacket.GetBytes(), 1, path.EndpointA.ChannelConfig.PortID, path.EndpointA.ChannelID, path.EndpointB.ChannelConfig.PortID, path.EndpointB.ChannelID, timeoutHeight, 0)
 	err = path.RelayPacket(packet)
 	suite.Require().NoError(err) // relay committed
 
@@ -82,18 +81,18 @@ func (suite *TransferTestSuite) TestHandleMsgTransfer() {
 
 	// send from chainB to chainC
 	msg = types.NewMsgTransfer(pathBtoC.EndpointA.ChannelConfig.PortID, pathBtoC.EndpointA.ChannelID, coinSentFromAToB, suite.chainB.SenderAccount.GetAddress().String(), suite.chainC.SenderAccount.GetAddress().String(), timeoutHeight, 0)
-
-	_, err = suite.chainB.SendMsgs(msg)
+	res, err = suite.chainB.SendMsgs(msg)
 	suite.Require().NoError(err) // message committed
 
-	// relay send
-	// NOTE: fungible token is prefixed with the full trace in order to verify the packet commitment
-	fullDenomPath := types.GetPrefixedDenom(pathBtoC.EndpointB.ChannelConfig.PortID, pathBtoC.EndpointB.ChannelID, voucherDenomTrace.GetFullDenomPath())
-	fungibleTokenPacket = types.NewFungibleTokenPacketData(voucherDenomTrace.GetFullDenomPath(), coinSentFromAToB.Amount.String(), suite.chainB.SenderAccount.GetAddress().String(), suite.chainC.SenderAccount.GetAddress().String())
-	packet = channeltypes.NewPacket(fungibleTokenPacket.GetBytes(), 1, pathBtoC.EndpointA.ChannelConfig.PortID, pathBtoC.EndpointA.ChannelID, pathBtoC.EndpointB.ChannelConfig.PortID, pathBtoC.EndpointB.ChannelID, timeoutHeight, 0)
+	packet, err = ibctesting.ParsePacketFromEvents(res.GetEvents())
+	suite.Require().NoError(err)
+
 	err = pathBtoC.RelayPacket(packet)
 	suite.Require().NoError(err) // relay committed
 
+	// NOTE: fungible token is prefixed with the full trace in order to verify the packet commitment
+	fullDenomPath := types.GetPrefixedDenom(pathBtoC.EndpointB.ChannelConfig.PortID, pathBtoC.EndpointB.ChannelID, voucherDenomTrace.GetFullDenomPath())
+
 	coinSentFromBToC := sdk.NewCoin(types.ParseDenomTrace(fullDenomPath).IBCDenom(), amount)
 	balance = suite.chainC.GetSimApp().BankKeeper.GetBalance(suite.chainC.GetContext(), suite.chainC.SenderAccount.GetAddress(), coinSentFromBToC.Denom)
 
@@ -106,14 +105,12 @@ func (suite *TransferTestSuite) TestHandleMsgTransfer() {
 
 	// send from chainC back to chainB
 	msg = types.NewMsgTransfer(pathBtoC.EndpointB.ChannelConfig.PortID, pathBtoC.EndpointB.ChannelID, coinSentFromBToC, suite.chainC.SenderAccount.GetAddress().String(), suite.chainB.SenderAccount.GetAddress().String(), timeoutHeight, 0)
-
-	_, err = suite.chainC.SendMsgs(msg)
+	res, err = suite.chainC.SendMsgs(msg)
 	suite.Require().NoError(err) // message committed
 
-	// relay send
-	// NOTE: fungible token is prefixed with the full trace in order to verify the packet commitment
-	fungibleTokenPacket = types.NewFungibleTokenPacketData(fullDenomPath, coinSentFromBToC.Amount.String(), suite.chainC.SenderAccount.GetAddress().String(), suite.chainB.SenderAccount.GetAddress().String())
-	packet = channeltypes.NewPacket(fungibleTokenPacket.GetBytes(), 1, pathBtoC.EndpointB.ChannelConfig.PortID, pathBtoC.EndpointB.ChannelID, pathBtoC.EndpointA.ChannelConfig.PortID, pathBtoC.EndpointA.ChannelID, timeoutHeight, 0)
+	packet, err = ibctesting.ParsePacketFromEvents(res.GetEvents())
+	suite.Require().NoError(err)
+
 	err = pathBtoC.RelayPacket(packet)
 	suite.Require().NoError(err) // relay committed
 

testing/events.go

@@ -2,6 +2,7 @@ package ibctesting
 
 import (
 	"fmt"
+	"strconv"
 
 	sdk "github.com/cosmos/cosmos-sdk/types"
 
@@ -56,6 +57,65 @@ func ParseChannelIDFromEvents(events sdk.Events) (string, error) {
 	return "", fmt.Errorf("channel identifier event attribute not found")
 }
 
+// ParsePacketFromEvents parses events emitted from a MsgRecvPacket and returns the
+// acknowledgement.
+func ParsePacketFromEvents(events sdk.Events) (channeltypes.Packet, error) {
+	for _, ev := range events {
+		if ev.Type == channeltypes.EventTypeSendPacket {
+			packet := channeltypes.Packet{}
+			for _, attr := range ev.Attributes {
+
+				switch string(attr.Key) {
+				case channeltypes.AttributeKeyData:
+					packet.Data = attr.Value
+
+				case channeltypes.AttributeKeySequence:
+					seq, err := strconv.ParseUint(string(attr.Value), 10, 64)
+					if err != nil {
+						return channeltypes.Packet{}, err
+					}
+
+					packet.Sequence = seq
+
+				case channeltypes.AttributeKeySrcPort:
+					packet.SourcePort = string(attr.Value)
+
+				case channeltypes.AttributeKeySrcChannel:
+					packet.SourceChannel = string(attr.Value)
+
+				case channeltypes.AttributeKeyDstPort:
+					packet.DestinationPort = string(attr.Value)
+
+				case channeltypes.AttributeKeyDstChannel:
+					packet.DestinationChannel = string(attr.Value)
+
+				case channeltypes.AttributeKeyTimeoutHeight:
+					height, err := clienttypes.ParseHeight(string(attr.Value))
+					if err != nil {
+						return channeltypes.Packet{}, err
+					}
+
+					packet.TimeoutHeight = height
+
+				case channeltypes.AttributeKeyTimeoutTimestamp:
+					timestamp, err := strconv.ParseUint(string(attr.Value), 10, 64)
+					if err != nil {
+						return channeltypes.Packet{}, err
+					}
+
+					packet.TimeoutTimestamp = timestamp
+
+				default:
+					continue
+				}
+			}
+
+			return packet, nil
+		}
+	}
+	return channeltypes.Packet{}, fmt.Errorf("acknowledgement event attribute not found")
+}
+
 // ParseAckFromEvents parses events emitted from a MsgRecvPacket and returns the
 // acknowledgement.
 func ParseAckFromEvents(events sdk.Events) ([]byte, error) {