fix: ensure withdraw_rewards events are always emitted on reward withdrawal

CHANGELOG.md

@@ -54,6 +54,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### Improvements
 
+* [#13323](https://github.com/cosmos/cosmos-sdk/pull/13323) Ensure `withdraw_rewards` rewards are emitted from all actions that result in rewards being withdrawn.
 * [#13214](https://github.com/cosmos/cosmos-sdk/pull/13214) Add `withdraw-proposal` command to group module's CLI transaction commands.
 * [#13070](https://github.com/cosmos/cosmos-sdk/pull/13070) Migrate from `gogo/protobuf` to `cosmos/gogoproto`.
 * [#12981](https://github.com/cosmos/cosmos-sdk/pull/12981) Return proper error when parsing telemetry configuration.

tests/integration/distribution/keeper/delegation_test.go

@@ -804,19 +804,15 @@ func Test100PercentCommissionReward(t *testing.T) {
 	rewards, err := distrKeeper.WithdrawDelegationRewards(ctx, sdk.AccAddress(valAddrs[0]), valAddrs[0])
 	require.NoError(t, err)
 
-	denom, _ := sdk.GetBaseDenom()
-	zeroRewards := sdk.Coins{
-		sdk.Coin{
-			Denom:  denom,
-			Amount: math.ZeroInt(),
-		},
-	}
+	zeroRewards := sdk.Coins{sdk.NewCoin(sdk.DefaultBondDenom, math.ZeroInt())}
 	require.True(t, rewards.IsEqual(zeroRewards))
+
 	events := ctx.EventManager().Events()
 	lastEvent := events[len(events)-1]
-	hasValue := false
+
+	var hasValue bool
 	for _, attr := range lastEvent.Attributes {
-		if string(attr.Key) == "amount" && string(attr.Value) == "0" {
+		if attr.Key == "amount" && attr.Value == "0stake" {
 			hasValue = true
 		}
 	}

testutil/sims/app_helpers.go

@@ -14,6 +14,7 @@ import (
 
 	"cosmossdk.io/depinject"
 	"cosmossdk.io/math"
+
 	"github.com/cosmos/cosmos-sdk/client/flags"
 	"github.com/cosmos/cosmos-sdk/codec"
 	codectypes "github.com/cosmos/cosmos-sdk/codec/types"
@@ -186,8 +187,11 @@ func SetupWithConfiguration(appConfig depinject.Config, startupConfig StartupCon
 }
 
 // GenesisStateWithValSet returns a new genesis state with the validator set
-func GenesisStateWithValSet(codec codec.Codec, genesisState map[string]json.RawMessage,
-	valSet *tmtypes.ValidatorSet, genAccs []authtypes.GenesisAccount,
+func GenesisStateWithValSet(
+	codec codec.Codec,
+	genesisState map[string]json.RawMessage,
+	valSet *tmtypes.ValidatorSet,
+	genAccs []authtypes.GenesisAccount,
 	balances ...banktypes.Balance,
 ) (map[string]json.RawMessage, error) {
 	// set genesis accounts
@@ -227,6 +231,7 @@ func GenesisStateWithValSet(codec codec.Codec, genesisState map[string]json.RawM
 		delegations = append(delegations, stakingtypes.NewDelegation(genAccs[0].GetAddress(), val.Address.Bytes(), math.LegacyOneDec()))
 
 	}
+
 	// set validators and delegations
 	stakingGenesis := stakingtypes.NewGenesisState(stakingtypes.DefaultParams(), validators, delegations)
 	genesisState[stakingtypes.ModuleName] = codec.MustMarshalJSON(stakingGenesis)

x/distribution/keeper/delegation.go

@@ -4,8 +4,8 @@ import (
 	"fmt"
 
 	"cosmossdk.io/math"
-	sdk "github.com/cosmos/cosmos-sdk/types"
 
+	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/x/distribution/types"
 	stakingtypes "github.com/cosmos/cosmos-sdk/x/staking/types"
 )
@@ -163,13 +163,13 @@ func (k Keeper) withdrawDelegationRewards(ctx sdk.Context, val stakingtypes.Vali
 		)
 	}
 
-	// truncate coins, return remainder to community pool
-	coins, remainder := rewards.TruncateDecimal()
+	// truncate reward dec coins, return remainder to community pool
+	finalRewards, remainder := rewards.TruncateDecimal()
 
 	// add coins to user account
-	if !coins.IsZero() {
+	if !finalRewards.IsZero() {
 		withdrawAddr := k.GetDelegatorWithdrawAddr(ctx, del.GetDelegatorAddr())
-		err := k.bankKeeper.SendCoinsFromModuleToAccount(ctx, types.ModuleName, withdrawAddr, coins)
+		err := k.bankKeeper.SendCoinsFromModuleToAccount(ctx, types.ModuleName, withdrawAddr, finalRewards)
 		if err != nil {
 			return nil, err
 		}
@@ -190,5 +190,24 @@ func (k Keeper) withdrawDelegationRewards(ctx sdk.Context, val stakingtypes.Vali
 	// remove delegator starting info
 	k.DeleteDelegatorStartingInfo(ctx, del.GetValidatorAddr(), del.GetDelegatorAddr())
 
-	return coins, nil
+	if finalRewards.IsZero() {
+		baseDenom, _ := sdk.GetBaseDenom()
+		if baseDenom == "" {
+			baseDenom = sdk.DefaultBondDenom
+		}
+
+		// Note, we do not call the NewCoins constructor as we do not want the zero
+		// coin removed.
+		finalRewards = sdk.Coins{sdk.NewCoin(baseDenom, math.ZeroInt())}
+	}
+
+	ctx.EventManager().EmitEvent(
+		sdk.NewEvent(
+			types.EventTypeWithdrawRewards,
+			sdk.NewAttribute(sdk.AttributeKeyAmount, finalRewards.String()),
+			sdk.NewAttribute(types.AttributeKeyValidator, val.GetOperator().String()),
+		),
+	)
+
+	return finalRewards, nil
 }

x/distribution/keeper/delegation_test.go

@@ -8,6 +8,7 @@ import (
 	tmproto "github.com/tendermint/tendermint/proto/tendermint/types"
 
 	"cosmossdk.io/math"
+
 	"github.com/cosmos/cosmos-sdk/testutil"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	moduletestutil "github.com/cosmos/cosmos-sdk/types/module/testutil"
@@ -959,19 +960,15 @@ func Test100PercentCommissionReward(t *testing.T) {
 	rewards, err := distrKeeper.WithdrawDelegationRewards(ctx, sdk.AccAddress(addr), valAddr)
 	require.NoError(t, err)
 
-	denom, _ := sdk.GetBaseDenom()
-	zeroRewards := sdk.Coins{
-		sdk.Coin{
-			Denom:  denom,
-			Amount: math.ZeroInt(),
-		},
-	}
+	zeroRewards := sdk.Coins{sdk.NewCoin(sdk.DefaultBondDenom, math.ZeroInt())}
 	require.True(t, rewards.IsEqual(zeroRewards))
+
 	events := ctx.EventManager().Events()
 	lastEvent := events[len(events)-1]
-	hasValue := false
+
+	var hasValue bool
 	for _, attr := range lastEvent.Attributes {
-		if string(attr.Key) == "amount" && string(attr.Value) == "0" {
+		if attr.Key == "amount" && attr.Value == "0stake" {
 			hasValue = true
 		}
 	}

x/distribution/keeper/keeper.go

@@ -3,7 +3,6 @@ package keeper
 import (
 	"fmt"
 
-	"cosmossdk.io/math"
 	"github.com/tendermint/tendermint/libs/log"
 
 	"github.com/cosmos/cosmos-sdk/codec"
@@ -98,22 +97,6 @@ func (k Keeper) WithdrawDelegationRewards(ctx sdk.Context, delAddr sdk.AccAddres
 		return nil, err
 	}
 
-	if rewards.IsZero() {
-		baseDenom, _ := sdk.GetBaseDenom()
-		rewards = sdk.Coins{sdk.Coin{
-			Denom:  baseDenom,
-			Amount: math.ZeroInt(),
-		}}
-	}
-
-	ctx.EventManager().EmitEvent(
-		sdk.NewEvent(
-			types.EventTypeWithdrawRewards,
-			sdk.NewAttribute(sdk.AttributeKeyAmount, rewards.String()),
-			sdk.NewAttribute(types.AttributeKeyValidator, valAddr.String()),
-		),
-	)
-
 	// reinitialize the delegation
 	k.initializeDelegation(ctx, valAddr, delAddr)
 	return rewards, nil