From c7ed944503857be66e981057d6e6815ac6c745bf Mon Sep 17 00:00:00 2001
From: Denali Marsh <denali@kava.io>
Date: Wed, 24 Mar 2021 00:44:37 +0100
Subject: [PATCH] fix delegation reward index (#888)

---
 x/incentive/keeper/rewards.go      | 10 +++-------
 x/incentive/keeper/rewards_test.go | 28 ++++++++++++++++++++++++----
 2 files changed, 27 insertions(+), 11 deletions(-)

diff --git a/x/incentive/keeper/rewards.go b/x/incentive/keeper/rewards.go
index aa70463a..d090907c 100644
--- a/x/incentive/keeper/rewards.go
+++ b/x/incentive/keeper/rewards.go
@@ -515,8 +515,8 @@ func (k Keeper) SynchronizeHardDelegatorRewards(ctx sdk.Context, delegator sdk.A
 
 	userRewardFactor := claim.DelegatorRewardIndexes[delegatorIndex].RewardFactor
 	rewardsAccumulatedFactor := delagatorFactor.Sub(userRewardFactor)
-	if rewardsAccumulatedFactor.IsZero() {
-		return
+	if rewardsAccumulatedFactor.IsNegative() {
+		panic(fmt.Sprintf("reward accumulation factor cannot be negative: %s", rewardsAccumulatedFactor))
 	}
 	claim.DelegatorRewardIndexes[delegatorIndex].RewardFactor = delagatorFactor
 
@@ -539,16 +539,12 @@ func (k Keeper) SynchronizeHardDelegatorRewards(ctx sdk.Context, delegator sdk.A
 		}
 
 		delegatedTokens := validator.TokensFromShares(delegation.GetShares())
-		if delegatedTokens.IsZero() || delegatedTokens.IsNegative() {
+		if delegatedTokens.IsNegative() {
 			continue
 		}
 		totalDelegated = totalDelegated.Add(delegatedTokens)
 	}
-
 	rewardsEarned := rewardsAccumulatedFactor.Mul(totalDelegated).RoundInt()
-	if rewardsEarned.IsZero() || rewardsEarned.IsNegative() {
-		return
-	}
 
 	// Add rewards to delegator's hard claim
 	newRewardsCoin := sdk.NewCoin(types.HardLiquidityRewardDenom, rewardsEarned)
diff --git a/x/incentive/keeper/rewards_test.go b/x/incentive/keeper/rewards_test.go
index 48e0e36f..02062602 100644
--- a/x/incentive/keeper/rewards_test.go
+++ b/x/incentive/keeper/rewards_test.go
@@ -2324,6 +2324,17 @@ func (suite *KeeperTestSuite) TestSynchronizeHardDelegatorReward() {
 				expectedRewards:      cs(c("hard", 52856928000)),
 			},
 		},
+		{
+			"delegator reward index updated when reward is zero",
+			args{
+				delegation:           c("ukava", 1),
+				rewardsPerSecond:     c("hard", 1),
+				initialTime:          time.Date(2020, 12, 15, 14, 0, 0, 0, time.UTC),
+				blockTimes:           []int{10, 10, 10, 10, 10, 10, 10, 10, 10, 10},
+				expectedRewardFactor: d("0.000099999900000100"),
+				expectedRewards:      nil,
+			},
+		},
 	}
 	for _, tc := range testCases {
 		suite.Run(tc.name, func() {
@@ -2351,13 +2362,22 @@ func (suite *KeeperTestSuite) TestSynchronizeHardDelegatorReward() {
 			// Set up hard state (interest factor for the relevant denom)
 			suite.hardKeeper.SetPreviousAccrualTime(suite.ctx, tc.args.delegation.Denom, tc.args.initialTime)
 
-			// Delegator delegates
-			err := suite.deliverMsgCreateValidator(suite.ctx, suite.validatorAddrs[0], tc.args.delegation)
+			// Create validator account
+			staking.BeginBlocker(suite.ctx, suite.stakingKeeper)
+			selfDelegationCoins := c("ukava", 1_000_000)
+			err := suite.deliverMsgCreateValidator(suite.ctx, suite.validatorAddrs[0], selfDelegationCoins)
 			suite.Require().NoError(err)
-			suite.deliverMsgDelegate(suite.ctx, suite.addrs[0], suite.validatorAddrs[0], tc.args.delegation)
+			staking.EndBlocker(suite.ctx, suite.stakingKeeper)
+
+			// Delegator delegates
+			err = suite.deliverMsgDelegate(suite.ctx, suite.addrs[0], suite.validatorAddrs[0], tc.args.delegation)
 			suite.Require().NoError(err)
 
-			staking.EndBlocker(suite.ctx, suite.stakingKeeper)
+			// Check that validator account has been created and delegation was successful
+			valAcc, found := suite.stakingKeeper.GetValidator(suite.ctx, suite.validatorAddrs[0])
+			suite.True(found)
+			suite.Require().Equal(valAcc.Status, sdk.Bonded)
+			suite.Require().Equal(valAcc.Tokens, tc.args.delegation.Amount.Add(selfDelegationCoins.Amount))
 
 			// Check that Staking hooks initialized a HardLiquidityProviderClaim
 			claim, found := suite.keeper.GetHardLiquidityProviderClaim(suite.ctx, suite.addrs[0])