From 410b9c50d3ed8d71cac28936820e6542e7b598b8 Mon Sep 17 00:00:00 2001
From: Amir Bandeali <abandeali1@gmail.com>
Date: Tue, 24 Sep 2019 23:01:31 -0700
Subject: [PATCH 1/9] Flatten _withdrawAndSyncDelegatorRewards function, fix
 bug where cumulative rewards are always reset

---
 .../contracts/src/stake/MixinStake.sol        |  16 +--
 .../staking_pools/MixinCumulativeRewards.sol  |  57 ++--------
 .../staking_pools/MixinStakingPoolRewards.sol | 100 +++++++-----------
 3 files changed, 60 insertions(+), 113 deletions(-)

diff --git a/contracts/staking/contracts/src/stake/MixinStake.sol b/contracts/staking/contracts/src/stake/MixinStake.sol
index 05329b1806..013aa9167e 100644
--- a/contracts/staking/contracts/src/stake/MixinStake.sol
+++ b/contracts/staking/contracts/src/stake/MixinStake.sol
@@ -188,7 +188,7 @@ contract MixinStake is
         _assertStakingPoolExists(poolId);
 
         // Cache amount delegated to pool by staker.
-        IStructs.StoredBalance memory initDelegatedStakeToPoolByOwner =
+        IStructs.StoredBalance memory initDelegatedStake =
             _loadUnsyncedBalance(_delegatedStakeToPoolByOwner[staker][poolId]);
 
         // Increment how much stake the staker has delegated to the input pool.
@@ -202,14 +202,14 @@ contract MixinStake is
 
         // Synchronizes reward state in the pool that the owner is delegating
         // to.
-        IStructs.StoredBalance memory finalDelegatedStakeToPoolByOwner =
+        IStructs.StoredBalance memory finalDelegatedStake =
             _loadSyncedBalance(_delegatedStakeToPoolByOwner[staker][poolId]);
 
         _withdrawAndSyncDelegatorRewards(
             poolId,
             staker,
-            initDelegatedStakeToPoolByOwner,
-            finalDelegatedStakeToPoolByOwner
+            initDelegatedStake,
+            finalDelegatedStake
         );
     }
 
@@ -228,7 +228,7 @@ contract MixinStake is
         _assertStakingPoolExists(poolId);
 
         // cache amount delegated to pool by staker
-        IStructs.StoredBalance memory initDelegatedStakeToPoolByOwner =
+        IStructs.StoredBalance memory initDelegatedStake =
             _loadUnsyncedBalance(_delegatedStakeToPoolByOwner[staker][poolId]);
 
         // decrement how much stake the staker has delegated to the input pool
@@ -242,14 +242,14 @@ contract MixinStake is
 
         // synchronizes reward state in the pool that the owner is undelegating
         // from
-        IStructs.StoredBalance memory finalDelegatedStakeToPoolByOwner =
+        IStructs.StoredBalance memory finalDelegatedStake =
             _loadSyncedBalance(_delegatedStakeToPoolByOwner[staker][poolId]);
 
         _withdrawAndSyncDelegatorRewards(
             poolId,
             staker,
-            initDelegatedStakeToPoolByOwner,
-            finalDelegatedStakeToPoolByOwner
+            initDelegatedStake,
+            finalDelegatedStake
         );
     }
 
diff --git a/contracts/staking/contracts/src/staking_pools/MixinCumulativeRewards.sol b/contracts/staking/contracts/src/staking_pools/MixinCumulativeRewards.sol
index 8df5fba0b6..45d1bb1b12 100644
--- a/contracts/staking/contracts/src/staking_pools/MixinCumulativeRewards.sol
+++ b/contracts/staking/contracts/src/staking_pools/MixinCumulativeRewards.sol
@@ -57,27 +57,6 @@ contract MixinCumulativeRewards is
         return cumulativeReward.denominator != 0;
     }
 
-    /// @dev Tries to set a cumulative reward for `poolId` at `epoch`.
-    /// @param poolId Unique Id of pool.
-    /// @param epoch Epoch of cumulative reward.
-    /// @param value Value of cumulative reward.
-    function _trySetCumulativeReward(
-        bytes32 poolId,
-        uint256 epoch,
-        IStructs.Fraction memory value
-    )
-        internal
-    {
-        // Do nothing if it's in the past since we don't want to
-        // rewrite history.
-        if (epoch < currentEpoch
-            && _isCumulativeRewardSet(_cumulativeRewardsByPool[poolId][epoch]))
-        {
-            return;
-        }
-        _forceSetCumulativeReward(poolId, epoch, value);
-    }
-
     /// @dev Sets a cumulative reward for `poolId` at `epoch`.
     /// This can be used to overwrite an existing value.
     /// @param poolId Unique Id of pool.
@@ -95,33 +74,19 @@ contract MixinCumulativeRewards is
         // Never set the most recent reward epoch to one in the future, because
         // it may get removed if there are no more dependencies on it.
         if (epoch <= currentEpoch) {
-            _trySetMostRecentCumulativeRewardEpoch(poolId, epoch);
-        }
-    }
+            // Check if we should do any work
+            uint256 currentMostRecentEpoch = _cumulativeRewardsByPoolLastStored[poolId];
+            if (epoch == currentMostRecentEpoch) {
+                return;
+            }
 
-    /// @dev Tries to set the epoch of the most recent cumulative reward.
-    ///      The value will only be set if the input epoch is greater than the
-    ///     current most recent value.
-    /// @param poolId Unique Id of pool.
-    /// @param epoch Epoch of the most recent cumulative reward.
-    function _trySetMostRecentCumulativeRewardEpoch(
-        bytes32 poolId,
-        uint256 epoch
-    )
-        internal
-    {
-        // Check if we should do any work
-        uint256 currentMostRecentEpoch = _cumulativeRewardsByPoolLastStored[poolId];
-        if (epoch == currentMostRecentEpoch) {
-            return;
+            // Update state to reflect the most recent cumulative reward
+            _forceSetMostRecentCumulativeRewardEpoch(
+                poolId,
+                currentMostRecentEpoch,
+                epoch
+            );
         }
-
-        // Update state to reflect the most recent cumulative reward
-        _forceSetMostRecentCumulativeRewardEpoch(
-            poolId,
-            currentMostRecentEpoch,
-            epoch
-        );
     }
 
     /// @dev Forcefully sets the epoch of the most recent cumulative reward.
diff --git a/contracts/staking/contracts/src/staking_pools/MixinStakingPoolRewards.sol b/contracts/staking/contracts/src/staking_pools/MixinStakingPoolRewards.sol
index e03c10d386..5aba12522a 100644
--- a/contracts/staking/contracts/src/staking_pools/MixinStakingPoolRewards.sol
+++ b/contracts/staking/contracts/src/staking_pools/MixinStakingPoolRewards.sol
@@ -44,21 +44,23 @@ contract MixinStakingPoolRewards is
     {
         address member = msg.sender;
 
-        IStructs.StoredBalance memory finalDelegatedStakeToPoolByOwner =
+        IStructs.StoredBalance memory finalDelegatedStake =
             _loadSyncedBalance(_delegatedStakeToPoolByOwner[member][poolId]);
 
+        IStructs.StoredBalance memory initDelegatedStake =
+            _loadUnsyncedBalance(_delegatedStakeToPoolByOwner[member][poolId]);
+
         _withdrawAndSyncDelegatorRewards(
             poolId,
             member,
-            // Initial balance
-            _loadUnsyncedBalance(_delegatedStakeToPoolByOwner[member][poolId]),
-            finalDelegatedStakeToPoolByOwner
+            initDelegatedStake,
+            finalDelegatedStake
         );
 
         // Update stored balance with synchronized version; this prevents
         // redundant withdrawals.
         _delegatedStakeToPoolByOwner[member][poolId] =
-            finalDelegatedStakeToPoolByOwner;
+            finalDelegatedStake;
     }
 
     /// @dev Computes the reward balance in ETH of the operator of a pool.
@@ -118,32 +120,45 @@ contract MixinStakingPoolRewards is
     ///      withdrawing rewards and adding/removing dependencies on cumulative rewards.
     /// @param poolId Unique id of pool.
     /// @param member of the pool.
-    /// @param initialDelegatedStakeToPoolByOwner The member's delegated
+    /// @param initDelegatedStake The member's delegated
     ///        balance at the beginning of this transaction.
-    /// @param finalDelegatedStakeToPoolByOwner The member's delegated balance
+    /// @param finalDelegatedStake The member's delegated balance
     ///        at the end of this transaction.
     function _withdrawAndSyncDelegatorRewards(
         bytes32 poolId,
         address member,
-        IStructs.StoredBalance memory initialDelegatedStakeToPoolByOwner,
-        IStructs.StoredBalance memory finalDelegatedStakeToPoolByOwner
+        IStructs.StoredBalance memory initDelegatedStake,
+        IStructs.StoredBalance memory finalDelegatedStake
     )
         internal
     {
-        // Withdraw any rewards from.
-        // this must be done before we can modify the staker's portion of the
-        // delegator pool.
-        _finalizePoolAndWithdrawDelegatorRewards(
+        // Ensure the pool is finalized.
+        finalizePool(poolId);
+
+        // Compute balance owed to delegator
+        uint256 balance = _computeDelegatorReward(
             poolId,
-            member,
-            initialDelegatedStakeToPoolByOwner
+            initDelegatedStake,
+            // No unfinalized values because we ensured the pool is already
+            // finalized.
+            0,
+            0
         );
 
+        // Withdraw non-0 balance
+        if (balance != 0) {
+            // Decrease the balance of the pool
+            _decreasePoolRewards(poolId, balance);
+
+            // Withdraw the member's WETH balance
+            getWethContract().transfer(member, balance);
+        }
+
         // Add dependencies on cumulative rewards for this epoch and the next
         // epoch, if necessary.
         _setCumulativeRewardDependenciesForDelegator(
             poolId,
-            finalDelegatedStakeToPoolByOwner
+            finalDelegatedStake
         );
     }
 
@@ -244,41 +259,6 @@ contract MixinStakingPoolRewards is
         return (operatorReward, membersReward);
     }
 
-    /// @dev Transfers a delegators accumulated rewards to the delegator.
-    ///      This is required before the member's stake in the pool can be modified.
-    /// @param poolId Unique id of pool.
-    /// @param member The member of the pool.
-    /// @param unsyncedStake Unsynced stake of the delegator to the pool.
-    function _finalizePoolAndWithdrawDelegatorRewards(
-        bytes32 poolId,
-        address member,
-        IStructs.StoredBalance memory unsyncedStake
-    )
-        private
-    {
-        // Ensure the pool is finalized.
-        finalizePool(poolId);
-
-        // Compute balance owed to delegator
-        uint256 balance = _computeDelegatorReward(
-            poolId,
-            unsyncedStake,
-            // No unfinalized values because we ensured the pool is already
-            // finalized.
-            0,
-            0
-        );
-        if (balance == 0) {
-            return;
-        }
-
-        // Decrease the balance of the pool
-        _decreasePoolRewards(poolId, balance);
-
-        // Withdraw the member's WETH balance
-        getWethContract().transfer(member, balance);
-    }
-
     /// @dev Computes the reward balance in ETH of a specific member of a pool.
     /// @param poolId Unique id of pool.
     /// @param unsyncedStake Unsynced delegated stake to pool by staker
@@ -388,11 +368,11 @@ contract MixinStakingPoolRewards is
     ///      A delegator always depends on the cumulative reward for the current
     ///      and next epoch, if they would still have stake in the next epoch.
     /// @param poolId Unique id of pool.
-    /// @param _delegatedStakeToPoolByOwner Amount of stake the member has
+    /// @param finalDelegatedStake Amount of stake the member has
     ///        delegated to the pool.
     function _setCumulativeRewardDependenciesForDelegator(
         bytes32 poolId,
-        IStructs.StoredBalance memory _delegatedStakeToPoolByOwner
+        IStructs.StoredBalance memory finalDelegatedStake
     )
         private
     {
@@ -402,16 +382,18 @@ contract MixinStakingPoolRewards is
 
         // The delegator depends on the Cumulative Reward for this epoch
         // only if they are currently staked or will be staked next epoch.
-        if (_delegatedStakeToPoolByOwner.currentEpochBalance == 0 && _delegatedStakeToPoolByOwner.nextEpochBalance == 0) {
+        if (finalDelegatedStake.currentEpochBalance == 0 && finalDelegatedStake.nextEpochBalance == 0) {
             return;
         }
 
         // Delegator depends on the Cumulative Reward for this epoch - ensure it is set.
-        _trySetCumulativeReward(
-            poolId,
-            _delegatedStakeToPoolByOwner.currentEpoch,
-            mostRecentCumulativeReward
-        );
+        if (!_isCumulativeRewardSet(_cumulativeRewardsByPool[poolId][finalDelegatedStake.currentEpoch])) {
+            _forceSetCumulativeReward(
+                poolId,
+                finalDelegatedStake.currentEpoch,
+                mostRecentCumulativeReward
+            );
+        }
     }
 
     /// @dev Increases rewards for a pool.

From c1871b5bca204926a6547042e59676b6aa655bbd Mon Sep 17 00:00:00 2001
From: Amir Bandeali <abandeali1@gmail.com>
Date: Tue, 24 Sep 2019 23:01:44 -0700
Subject: [PATCH 2/9] Fix xumulative reward tests

---
 contracts/staking/test/cumulative_reward_tracking_test.ts | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/contracts/staking/test/cumulative_reward_tracking_test.ts b/contracts/staking/test/cumulative_reward_tracking_test.ts
index e23191ee6d..5e1df454f4 100644
--- a/contracts/staking/test/cumulative_reward_tracking_test.ts
+++ b/contracts/staking/test/cumulative_reward_tracking_test.ts
@@ -53,7 +53,7 @@ blockchainTests.resets('Cumulative Reward Tracking', env => {
                     // Creates CR for epoch 1
                     TestAction.Delegate,
                 ],
-                [{ event: 'SetCumulativeReward', epoch: 0 }],
+                [],
             );
         });
         it('re-delegating in the same epoch', async () => {
@@ -68,7 +68,7 @@ blockchainTests.resets('Cumulative Reward Tracking', env => {
                     // Updates CR for epoch 0
                     TestAction.Delegate,
                 ],
-                [{ event: 'SetCumulativeReward', epoch: 0 }, { event: 'SetCumulativeReward', epoch: 0 }],
+                [],
             );
         });
         it('delegating in new epoch', async () => {
@@ -268,7 +268,7 @@ blockchainTests.resets('Cumulative Reward Tracking', env => {
                     // Clears CR for epoch 2
                     TestAction.Delegate,
                 ],
-                [{ event: 'SetCumulativeReward', epoch: 3 }],
+                [],
             );
         });
         it('delegate in epoch 0 and 1, earn reward in epoch 3, then undelegate half', async () => {
@@ -303,7 +303,7 @@ blockchainTests.resets('Cumulative Reward Tracking', env => {
                     // Clears CR for epoch 2
                     TestAction.Undelegate,
                 ],
-                [{ event: 'SetCumulativeReward', epoch: 3 }],
+                [],
             );
         });
         it('delegate in epoch 1, 2, earn rewards in epoch 3, skip to epoch 4, then delegate', async () => {

From d07005dcbe7d5187e232dd0a08a06a983612d6d6 Mon Sep 17 00:00:00 2001
From: Amir Bandeali <abandeali1@gmail.com>
Date: Tue, 24 Sep 2019 23:04:37 -0700
Subject: [PATCH 3/9] Change increment -> increase and decrement -> decrease

---
 .../staking/contracts/src/stake/MixinStake.sol   | 16 ++++++++--------
 .../contracts/src/stake/MixinStakeStorage.sol    |  8 ++++----
 2 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/contracts/staking/contracts/src/stake/MixinStake.sol b/contracts/staking/contracts/src/stake/MixinStake.sol
index 013aa9167e..0ed5fe3f5d 100644
--- a/contracts/staking/contracts/src/stake/MixinStake.sol
+++ b/contracts/staking/contracts/src/stake/MixinStake.sol
@@ -42,10 +42,10 @@ contract MixinStake is
         getZrxVault().depositFrom(staker, amount);
 
         // mint stake
-        _incrementCurrentAndNextBalance(_activeStakeByOwner[staker], amount);
+        _increaseCurrentAndNextBalance(_activeStakeByOwner[staker], amount);
 
         // update global total of active stake
-        _incrementCurrentAndNextBalance(globalStakeByStatus[uint8(IStructs.StakeStatus.ACTIVE)], amount);
+        _increaseCurrentAndNextBalance(globalStakeByStatus[uint8(IStructs.StakeStatus.ACTIVE)], amount);
 
         // notify
         emit Stake(
@@ -75,10 +75,10 @@ contract MixinStake is
         }
 
         // burn inactive stake
-        _decrementCurrentAndNextBalance(_inactiveStakeByOwner[staker], amount);
+        _decreaseCurrentAndNextBalance(_inactiveStakeByOwner[staker], amount);
 
         // update global total of inactive stake
-        _decrementCurrentAndNextBalance(globalStakeByStatus[uint8(IStructs.StakeStatus.INACTIVE)], amount);
+        _decreaseCurrentAndNextBalance(globalStakeByStatus[uint8(IStructs.StakeStatus.INACTIVE)], amount);
 
         // update withdrawable field
         _withdrawableStakeByOwner[staker] =
@@ -192,13 +192,13 @@ contract MixinStake is
             _loadUnsyncedBalance(_delegatedStakeToPoolByOwner[staker][poolId]);
 
         // Increment how much stake the staker has delegated to the input pool.
-        _incrementNextBalance(
+        _increaseNextBalance(
             _delegatedStakeToPoolByOwner[staker][poolId],
             amount
         );
 
         // Increment how much stake has been delegated to pool.
-        _incrementNextBalance(_delegatedStakeByPoolId[poolId], amount);
+        _increaseNextBalance(_delegatedStakeByPoolId[poolId], amount);
 
         // Synchronizes reward state in the pool that the owner is delegating
         // to.
@@ -232,13 +232,13 @@ contract MixinStake is
             _loadUnsyncedBalance(_delegatedStakeToPoolByOwner[staker][poolId]);
 
         // decrement how much stake the staker has delegated to the input pool
-        _decrementNextBalance(
+        _decreaseNextBalance(
             _delegatedStakeToPoolByOwner[staker][poolId],
             amount
         );
 
         // decrement how much stake has been delegated to pool
-        _decrementNextBalance(_delegatedStakeByPoolId[poolId], amount);
+        _decreaseNextBalance(_delegatedStakeByPoolId[poolId], amount);
 
         // synchronizes reward state in the pool that the owner is undelegating
         // from
diff --git a/contracts/staking/contracts/src/stake/MixinStakeStorage.sol b/contracts/staking/contracts/src/stake/MixinStakeStorage.sol
index 23ea0c7404..6588a0cc89 100644
--- a/contracts/staking/contracts/src/stake/MixinStakeStorage.sol
+++ b/contracts/staking/contracts/src/stake/MixinStakeStorage.sol
@@ -111,7 +111,7 @@ contract MixinStakeStorage is
     /// @dev Increments both the `current` and `next` fields.
     /// @param balancePtr storage pointer to balance.
     /// @param amount to mint.
-    function _incrementCurrentAndNextBalance(IStructs.StoredBalance storage balancePtr, uint256 amount)
+    function _increaseCurrentAndNextBalance(IStructs.StoredBalance storage balancePtr, uint256 amount)
         internal
     {
         // Remove stake from balance
@@ -126,7 +126,7 @@ contract MixinStakeStorage is
     /// @dev Decrements both the `current` and `next` fields.
     /// @param balancePtr storage pointer to balance.
     /// @param amount to mint.
-    function _decrementCurrentAndNextBalance(IStructs.StoredBalance storage balancePtr, uint256 amount)
+    function _decreaseCurrentAndNextBalance(IStructs.StoredBalance storage balancePtr, uint256 amount)
         internal
     {
         // Remove stake from balance
@@ -141,7 +141,7 @@ contract MixinStakeStorage is
     /// @dev Increments the `next` field (but not the `current` field).
     /// @param balancePtr storage pointer to balance.
     /// @param amount to increment by.
-    function _incrementNextBalance(IStructs.StoredBalance storage balancePtr, uint256 amount)
+    function _increaseNextBalance(IStructs.StoredBalance storage balancePtr, uint256 amount)
         internal
     {
         // Add stake to balance
@@ -155,7 +155,7 @@ contract MixinStakeStorage is
     /// @dev Decrements the `next` field (but not the `current` field).
     /// @param balancePtr storage pointer to balance.
     /// @param amount to decrement by.
-    function _decrementNextBalance(IStructs.StoredBalance storage balancePtr, uint256 amount)
+    function _decreaseNextBalance(IStructs.StoredBalance storage balancePtr, uint256 amount)
         internal
     {
         // Remove stake from balance

From 22a6de48ae3bc133f7d3f21ad506f7794127e8bb Mon Sep 17 00:00:00 2001
From: Amir Bandeali <abandeali1@gmail.com>
Date: Wed, 25 Sep 2019 10:43:14 -0700
Subject: [PATCH 4/9] Remove arguments that are unnecessarily passed around

---
 .../contracts/src/stake/MixinStake.sol        | 26 +---------
 .../staking_pools/MixinStakingPoolRewards.sol | 47 ++++++++-----------
 .../contracts/test/TestDelegatorRewards.sol   | 15 ++----
 3 files changed, 24 insertions(+), 64 deletions(-)

diff --git a/contracts/staking/contracts/src/stake/MixinStake.sol b/contracts/staking/contracts/src/stake/MixinStake.sol
index 0ed5fe3f5d..6dc3079500 100644
--- a/contracts/staking/contracts/src/stake/MixinStake.sol
+++ b/contracts/staking/contracts/src/stake/MixinStake.sol
@@ -187,10 +187,6 @@ contract MixinStake is
         // Sanity check the pool we're delegating to exists.
         _assertStakingPoolExists(poolId);
 
-        // Cache amount delegated to pool by staker.
-        IStructs.StoredBalance memory initDelegatedStake =
-            _loadUnsyncedBalance(_delegatedStakeToPoolByOwner[staker][poolId]);
-
         // Increment how much stake the staker has delegated to the input pool.
         _increaseNextBalance(
             _delegatedStakeToPoolByOwner[staker][poolId],
@@ -200,16 +196,9 @@ contract MixinStake is
         // Increment how much stake has been delegated to pool.
         _increaseNextBalance(_delegatedStakeByPoolId[poolId], amount);
 
-        // Synchronizes reward state in the pool that the owner is delegating
-        // to.
-        IStructs.StoredBalance memory finalDelegatedStake =
-            _loadSyncedBalance(_delegatedStakeToPoolByOwner[staker][poolId]);
-
         _withdrawAndSyncDelegatorRewards(
             poolId,
-            staker,
-            initDelegatedStake,
-            finalDelegatedStake
+            staker
         );
     }
 
@@ -227,10 +216,6 @@ contract MixinStake is
         // sanity check the pool we're undelegating from exists
         _assertStakingPoolExists(poolId);
 
-        // cache amount delegated to pool by staker
-        IStructs.StoredBalance memory initDelegatedStake =
-            _loadUnsyncedBalance(_delegatedStakeToPoolByOwner[staker][poolId]);
-
         // decrement how much stake the staker has delegated to the input pool
         _decreaseNextBalance(
             _delegatedStakeToPoolByOwner[staker][poolId],
@@ -240,16 +225,9 @@ contract MixinStake is
         // decrement how much stake has been delegated to pool
         _decreaseNextBalance(_delegatedStakeByPoolId[poolId], amount);
 
-        // synchronizes reward state in the pool that the owner is undelegating
-        // from
-        IStructs.StoredBalance memory finalDelegatedStake =
-            _loadSyncedBalance(_delegatedStakeToPoolByOwner[staker][poolId]);
-
         _withdrawAndSyncDelegatorRewards(
             poolId,
-            staker,
-            initDelegatedStake,
-            finalDelegatedStake
+            staker
         );
     }
 
diff --git a/contracts/staking/contracts/src/staking_pools/MixinStakingPoolRewards.sol b/contracts/staking/contracts/src/staking_pools/MixinStakingPoolRewards.sol
index 5aba12522a..f9e3c0a943 100644
--- a/contracts/staking/contracts/src/staking_pools/MixinStakingPoolRewards.sol
+++ b/contracts/staking/contracts/src/staking_pools/MixinStakingPoolRewards.sol
@@ -44,23 +44,15 @@ contract MixinStakingPoolRewards is
     {
         address member = msg.sender;
 
-        IStructs.StoredBalance memory finalDelegatedStake =
-            _loadSyncedBalance(_delegatedStakeToPoolByOwner[member][poolId]);
-
-        IStructs.StoredBalance memory initDelegatedStake =
-            _loadUnsyncedBalance(_delegatedStakeToPoolByOwner[member][poolId]);
-
         _withdrawAndSyncDelegatorRewards(
             poolId,
-            member,
-            initDelegatedStake,
-            finalDelegatedStake
+            member
         );
 
         // Update stored balance with synchronized version; this prevents
         // redundant withdrawals.
         _delegatedStakeToPoolByOwner[member][poolId] =
-            finalDelegatedStake;
+            _loadSyncedBalance(_delegatedStakeToPoolByOwner[member][poolId]);
     }
 
     /// @dev Computes the reward balance in ETH of the operator of a pool.
@@ -110,7 +102,7 @@ contract MixinStakingPoolRewards is
         );
         return _computeDelegatorReward(
             poolId,
-            _loadUnsyncedBalance(_delegatedStakeToPoolByOwner[member][poolId]),
+            member,
             unfinalizedMembersReward,
             unfinalizedMembersStake
         );
@@ -120,15 +112,9 @@ contract MixinStakingPoolRewards is
     ///      withdrawing rewards and adding/removing dependencies on cumulative rewards.
     /// @param poolId Unique id of pool.
     /// @param member of the pool.
-    /// @param initDelegatedStake The member's delegated
-    ///        balance at the beginning of this transaction.
-    /// @param finalDelegatedStake The member's delegated balance
-    ///        at the end of this transaction.
     function _withdrawAndSyncDelegatorRewards(
         bytes32 poolId,
-        address member,
-        IStructs.StoredBalance memory initDelegatedStake,
-        IStructs.StoredBalance memory finalDelegatedStake
+        address member
     )
         internal
     {
@@ -138,7 +124,7 @@ contract MixinStakingPoolRewards is
         // Compute balance owed to delegator
         uint256 balance = _computeDelegatorReward(
             poolId,
-            initDelegatedStake,
+            member,
             // No unfinalized values because we ensured the pool is already
             // finalized.
             0,
@@ -158,7 +144,7 @@ contract MixinStakingPoolRewards is
         // epoch, if necessary.
         _setCumulativeRewardDependenciesForDelegator(
             poolId,
-            finalDelegatedStake
+            member
         );
     }
 
@@ -261,13 +247,13 @@ contract MixinStakingPoolRewards is
 
     /// @dev Computes the reward balance in ETH of a specific member of a pool.
     /// @param poolId Unique id of pool.
-    /// @param unsyncedStake Unsynced delegated stake to pool by staker
+    /// @param member of the pool.
     /// @param unfinalizedMembersReward Unfinalized total members reward (if any).
     /// @param unfinalizedMembersStake Unfinalized total members stake (if any).
     /// @return reward Balance in WETH.
     function _computeDelegatorReward(
         bytes32 poolId,
-        IStructs.StoredBalance memory unsyncedStake,
+        address member,
         uint256 unfinalizedMembersReward,
         uint256 unfinalizedMembersStake
     )
@@ -282,6 +268,9 @@ contract MixinStakingPoolRewards is
             return 0;
         }
 
+        IStructs.StoredBalance memory unsyncedStake =
+            _loadUnsyncedBalance(_delegatedStakeToPoolByOwner[member][poolId]);
+
         // There can be no rewards if the last epoch when stake was synced is
         // equal to the current epoch, because all prior rewards, including
         // rewards finalized this epoch have been claimed.
@@ -368,17 +357,15 @@ contract MixinStakingPoolRewards is
     ///      A delegator always depends on the cumulative reward for the current
     ///      and next epoch, if they would still have stake in the next epoch.
     /// @param poolId Unique id of pool.
-    /// @param finalDelegatedStake Amount of stake the member has
-    ///        delegated to the pool.
+    /// @param member of the pool.
     function _setCumulativeRewardDependenciesForDelegator(
         bytes32 poolId,
-        IStructs.StoredBalance memory finalDelegatedStake
+        address member
     )
         private
     {
-        // Get the most recent cumulative reward, which will serve as a
-        // reference point when updating dependencies
-        IStructs.Fraction memory mostRecentCumulativeReward = _getMostRecentCumulativeReward(poolId);
+        IStructs.StoredBalance memory finalDelegatedStake =
+            _loadSyncedBalance(_delegatedStakeToPoolByOwner[member][poolId]);
 
         // The delegator depends on the Cumulative Reward for this epoch
         // only if they are currently staked or will be staked next epoch.
@@ -386,6 +373,10 @@ contract MixinStakingPoolRewards is
             return;
         }
 
+        // Get the most recent cumulative reward, which will serve as a
+        // reference point when updating dependencies
+        IStructs.Fraction memory mostRecentCumulativeReward = _getMostRecentCumulativeReward(poolId);
+
         // Delegator depends on the Cumulative Reward for this epoch - ensure it is set.
         if (!_isCumulativeRewardSet(_cumulativeRewardsByPool[poolId][finalDelegatedStake.currentEpoch])) {
             _forceSetCumulativeReward(
diff --git a/contracts/staking/contracts/test/TestDelegatorRewards.sol b/contracts/staking/contracts/test/TestDelegatorRewards.sol
index 5648c97f9e..2c4aa80c7a 100644
--- a/contracts/staking/contracts/test/TestDelegatorRewards.sol
+++ b/contracts/staking/contracts/test/TestDelegatorRewards.sol
@@ -110,7 +110,6 @@ contract TestDelegatorRewards is
         external
     {
         _initGenesisCumulativeRewards(poolId);
-        IStructs.StoredBalance memory initialStake = _delegatedStakeToPoolByOwner[delegator][poolId];
         IStructs.StoredBalance storage _stake = _delegatedStakeToPoolByOwner[delegator][poolId];
         _stake.isInitialized = true;
         _stake.currentEpochBalance += uint96(stake);
@@ -118,9 +117,7 @@ contract TestDelegatorRewards is
         _stake.currentEpoch = uint32(currentEpoch);
         _withdrawAndSyncDelegatorRewards(
             poolId,
-            delegator,
-            initialStake,
-            _stake
+            delegator
         );
     }
 
@@ -135,7 +132,6 @@ contract TestDelegatorRewards is
         external
     {
         _initGenesisCumulativeRewards(poolId);
-        IStructs.StoredBalance memory initialStake = _delegatedStakeToPoolByOwner[delegator][poolId];
         IStructs.StoredBalance storage _stake = _delegatedStakeToPoolByOwner[delegator][poolId];
         if (_stake.currentEpoch < currentEpoch) {
             _stake.currentEpochBalance = _stake.nextEpochBalance;
@@ -145,9 +141,7 @@ contract TestDelegatorRewards is
         _stake.currentEpoch = uint32(currentEpoch);
         _withdrawAndSyncDelegatorRewards(
             poolId,
-            delegator,
-            initialStake,
-            _stake
+            delegator
         );
     }
 
@@ -162,7 +156,6 @@ contract TestDelegatorRewards is
         external
     {
         _initGenesisCumulativeRewards(poolId);
-        IStructs.StoredBalance memory initialStake = _delegatedStakeToPoolByOwner[delegator][poolId];
         IStructs.StoredBalance storage _stake = _delegatedStakeToPoolByOwner[delegator][poolId];
         if (_stake.currentEpoch < currentEpoch) {
             _stake.currentEpochBalance = _stake.nextEpochBalance;
@@ -172,9 +165,7 @@ contract TestDelegatorRewards is
         _stake.currentEpoch = uint32(currentEpoch);
         _withdrawAndSyncDelegatorRewards(
             poolId,
-            delegator,
-            initialStake,
-            _stake
+            delegator
         );
     }
 

From 25cb1c11388abe73cabcde095ae26e29864f23b0 Mon Sep 17 00:00:00 2001
From: Amir Bandeali <abandeali1@gmail.com>
Date: Wed, 25 Sep 2019 10:58:16 -0700
Subject: [PATCH 5/9] Remove epoch param that is always equivalent to
 currentEpoch

---
 .../staking_pools/MixinCumulativeRewards.sol  | 32 ++++++++-----------
 .../staking_pools/MixinStakingPoolRewards.sol |  2 --
 .../test/TestCumulativeRewardTracking.sol     |  4 +--
 3 files changed, 14 insertions(+), 24 deletions(-)

diff --git a/contracts/staking/contracts/src/staking_pools/MixinCumulativeRewards.sol b/contracts/staking/contracts/src/staking_pools/MixinCumulativeRewards.sol
index 45d1bb1b12..755f706ced 100644
--- a/contracts/staking/contracts/src/staking_pools/MixinCumulativeRewards.sol
+++ b/contracts/staking/contracts/src/staking_pools/MixinCumulativeRewards.sol
@@ -37,7 +37,6 @@ contract MixinCumulativeRewards is
         // Sets the default cumulative reward
         _forceSetCumulativeReward(
             poolId,
-            currentEpoch,
             IStructs.Fraction({
                 numerator: 0,
                 denominator: MIN_TOKEN_VALUE
@@ -60,33 +59,28 @@ contract MixinCumulativeRewards is
     /// @dev Sets a cumulative reward for `poolId` at `epoch`.
     /// This can be used to overwrite an existing value.
     /// @param poolId Unique Id of pool.
-    /// @param epoch Epoch of cumulative reward.
     /// @param value Value of cumulative reward.
     function _forceSetCumulativeReward(
         bytes32 poolId,
-        uint256 epoch,
         IStructs.Fraction memory value
     )
         internal
     {
-        _cumulativeRewardsByPool[poolId][epoch] = value;
+        uint256 currentEpoch_ = currentEpoch;
+        _cumulativeRewardsByPool[poolId][currentEpoch_] = value;
 
-        // Never set the most recent reward epoch to one in the future, because
-        // it may get removed if there are no more dependencies on it.
-        if (epoch <= currentEpoch) {
-            // Check if we should do any work
-            uint256 currentMostRecentEpoch = _cumulativeRewardsByPoolLastStored[poolId];
-            if (epoch == currentMostRecentEpoch) {
-                return;
-            }
-
-            // Update state to reflect the most recent cumulative reward
-            _forceSetMostRecentCumulativeRewardEpoch(
-                poolId,
-                currentMostRecentEpoch,
-                epoch
-            );
+        // Check if we should do any work
+        uint256 currentMostRecentEpoch = _cumulativeRewardsByPoolLastStored[poolId];
+        if (currentEpoch_ == currentMostRecentEpoch) {
+            return;
         }
+
+        // Update state to reflect the most recent cumulative reward
+        _forceSetMostRecentCumulativeRewardEpoch(
+            poolId,
+            currentMostRecentEpoch,
+            currentEpoch_
+        );
     }
 
     /// @dev Forcefully sets the epoch of the most recent cumulative reward.
diff --git a/contracts/staking/contracts/src/staking_pools/MixinStakingPoolRewards.sol b/contracts/staking/contracts/src/staking_pools/MixinStakingPoolRewards.sol
index f9e3c0a943..99274b54e8 100644
--- a/contracts/staking/contracts/src/staking_pools/MixinStakingPoolRewards.sol
+++ b/contracts/staking/contracts/src/staking_pools/MixinStakingPoolRewards.sol
@@ -206,7 +206,6 @@ contract MixinStakingPoolRewards is
             // Store cumulative rewards for this epoch.
             _forceSetCumulativeReward(
                 poolId,
-                currentEpoch,
                 cumulativeReward
             );
         }
@@ -381,7 +380,6 @@ contract MixinStakingPoolRewards is
         if (!_isCumulativeRewardSet(_cumulativeRewardsByPool[poolId][finalDelegatedStake.currentEpoch])) {
             _forceSetCumulativeReward(
                 poolId,
-                finalDelegatedStake.currentEpoch,
                 mostRecentCumulativeReward
             );
         }
diff --git a/contracts/staking/contracts/test/TestCumulativeRewardTracking.sol b/contracts/staking/contracts/test/TestCumulativeRewardTracking.sol
index 6409ada717..a57f6c329e 100644
--- a/contracts/staking/contracts/test/TestCumulativeRewardTracking.sol
+++ b/contracts/staking/contracts/test/TestCumulativeRewardTracking.sol
@@ -51,15 +51,13 @@ contract TestCumulativeRewardTracking is
 
     function _forceSetCumulativeReward(
         bytes32 poolId,
-        uint256 epoch,
         IStructs.Fraction memory value
     )
         internal
     {
-        emit SetCumulativeReward(poolId, epoch);
+        emit SetCumulativeReward(poolId, currentEpoch);
         MixinCumulativeRewards._forceSetCumulativeReward(
             poolId,
-            epoch,
             value
         );
     }

From 44400754255ee55271b2469fba9ff6aaf45ba1f0 Mon Sep 17 00:00:00 2001
From: Amir Bandeali <abandeali1@gmail.com>
Date: Wed, 25 Sep 2019 11:03:26 -0700
Subject: [PATCH 6/9] Inline _forceSetMostRecentCumulativeRewardEpoch

---
 .../staking_pools/MixinCumulativeRewards.sol  | 25 ++-----------------
 .../test/TestCumulativeRewardTracking.sol     | 20 ---------------
 .../cumulative_reward_tracking_simulation.ts  |  7 +-----
 3 files changed, 3 insertions(+), 49 deletions(-)

diff --git a/contracts/staking/contracts/src/staking_pools/MixinCumulativeRewards.sol b/contracts/staking/contracts/src/staking_pools/MixinCumulativeRewards.sol
index 755f706ced..21368fc093 100644
--- a/contracts/staking/contracts/src/staking_pools/MixinCumulativeRewards.sol
+++ b/contracts/staking/contracts/src/staking_pools/MixinCumulativeRewards.sol
@@ -76,29 +76,8 @@ contract MixinCumulativeRewards is
         }
 
         // Update state to reflect the most recent cumulative reward
-        _forceSetMostRecentCumulativeRewardEpoch(
-            poolId,
-            currentMostRecentEpoch,
-            currentEpoch_
-        );
-    }
-
-    /// @dev Forcefully sets the epoch of the most recent cumulative reward.
-    /// @param poolId Unique Id of pool.
-    /// @param currentMostRecentEpoch Epoch of the most recent cumulative
-    ///        reward.
-    /// @param newMostRecentEpoch Epoch of the new most recent cumulative
-    ///        reward.
-    function _forceSetMostRecentCumulativeRewardEpoch(
-        bytes32 poolId,
-        uint256 currentMostRecentEpoch,
-        uint256 newMostRecentEpoch
-    )
-        internal
-    {
-        // Sanity check that we're not trying to go back in time
-        assert(newMostRecentEpoch >= currentMostRecentEpoch);
-        _cumulativeRewardsByPoolLastStored[poolId] = newMostRecentEpoch;
+        assert(currentEpoch_ > currentMostRecentEpoch);
+        _cumulativeRewardsByPoolLastStored[poolId] = currentEpoch_;
     }
 
     /// @dev Computes a member's reward over a given epoch interval.
diff --git a/contracts/staking/contracts/test/TestCumulativeRewardTracking.sol b/contracts/staking/contracts/test/TestCumulativeRewardTracking.sol
index a57f6c329e..8e74842989 100644
--- a/contracts/staking/contracts/test/TestCumulativeRewardTracking.sol
+++ b/contracts/staking/contracts/test/TestCumulativeRewardTracking.sol
@@ -30,11 +30,6 @@ contract TestCumulativeRewardTracking is
         uint256 epoch
     );
 
-    event SetMostRecentCumulativeReward(
-        bytes32 poolId,
-        uint256 epoch
-    );
-
     constructor(
         address wethAddress,
         address zrxVaultAddress
@@ -61,19 +56,4 @@ contract TestCumulativeRewardTracking is
             value
         );
     }
-
-    function _forceSetMostRecentCumulativeRewardEpoch(
-        bytes32 poolId,
-        uint256 currentMostRecentEpoch,
-        uint256 newMostRecentEpoch
-    )
-        internal
-    {
-        emit SetMostRecentCumulativeReward(poolId, newMostRecentEpoch);
-        MixinCumulativeRewards._forceSetMostRecentCumulativeRewardEpoch(
-            poolId,
-            currentMostRecentEpoch,
-            newMostRecentEpoch
-        );
-    }
 }
diff --git a/contracts/staking/test/utils/cumulative_reward_tracking_simulation.ts b/contracts/staking/test/utils/cumulative_reward_tracking_simulation.ts
index 516c0ffd31..675f079f25 100644
--- a/contracts/staking/test/utils/cumulative_reward_tracking_simulation.ts
+++ b/contracts/staking/test/utils/cumulative_reward_tracking_simulation.ts
@@ -36,12 +36,7 @@ export class CumulativeRewardTrackingSimulation {
     private static _extractTestLogs(txReceiptLogs: DecodedLogs): TestLog[] {
         const logs = [];
         for (const log of txReceiptLogs) {
-            if (log.event === TestCumulativeRewardTrackingEvents.SetMostRecentCumulativeReward) {
-                logs.push({
-                    event: log.event,
-                    epoch: log.args.epoch.toNumber(),
-                });
-            } else if (log.event === TestCumulativeRewardTrackingEvents.SetCumulativeReward) {
+            if (log.event === TestCumulativeRewardTrackingEvents.SetCumulativeReward) {
                 logs.push({
                     event: log.event,
                     epoch: log.args.epoch.toNumber(),

From 9e3331d0188714eaec1c6f0553fc04841eb79f1f Mon Sep 17 00:00:00 2001
From: Amir Bandeali <abandeali1@gmail.com>
Date: Wed, 25 Sep 2019 11:31:30 -0700
Subject: [PATCH 7/9] Fix ordering of function calls, remove optimization in
 _forceSetCumulativeReward

---
 .../contracts/src/stake/MixinStake.sol        | 20 +++++++++----------
 .../staking_pools/MixinCumulativeRewards.sol  | 11 +++-------
 2 files changed, 13 insertions(+), 18 deletions(-)

diff --git a/contracts/staking/contracts/src/stake/MixinStake.sol b/contracts/staking/contracts/src/stake/MixinStake.sol
index 6dc3079500..a77350fbd5 100644
--- a/contracts/staking/contracts/src/stake/MixinStake.sol
+++ b/contracts/staking/contracts/src/stake/MixinStake.sol
@@ -187,6 +187,11 @@ contract MixinStake is
         // Sanity check the pool we're delegating to exists.
         _assertStakingPoolExists(poolId);
 
+        _withdrawAndSyncDelegatorRewards(
+            poolId,
+            staker
+        );
+
         // Increment how much stake the staker has delegated to the input pool.
         _increaseNextBalance(
             _delegatedStakeToPoolByOwner[staker][poolId],
@@ -195,11 +200,6 @@ contract MixinStake is
 
         // Increment how much stake has been delegated to pool.
         _increaseNextBalance(_delegatedStakeByPoolId[poolId], amount);
-
-        _withdrawAndSyncDelegatorRewards(
-            poolId,
-            staker
-        );
     }
 
     /// @dev Un-Delegates a owners stake from a staking pool.
@@ -216,6 +216,11 @@ contract MixinStake is
         // sanity check the pool we're undelegating from exists
         _assertStakingPoolExists(poolId);
 
+        _withdrawAndSyncDelegatorRewards(
+            poolId,
+            staker
+        );
+
         // decrement how much stake the staker has delegated to the input pool
         _decreaseNextBalance(
             _delegatedStakeToPoolByOwner[staker][poolId],
@@ -224,11 +229,6 @@ contract MixinStake is
 
         // decrement how much stake has been delegated to pool
         _decreaseNextBalance(_delegatedStakeByPoolId[poolId], amount);
-
-        _withdrawAndSyncDelegatorRewards(
-            poolId,
-            staker
-        );
     }
 
     /// @dev Returns a storage pointer to a user's stake in a given status.
diff --git a/contracts/staking/contracts/src/staking_pools/MixinCumulativeRewards.sol b/contracts/staking/contracts/src/staking_pools/MixinCumulativeRewards.sol
index 21368fc093..ed5626049d 100644
--- a/contracts/staking/contracts/src/staking_pools/MixinCumulativeRewards.sol
+++ b/contracts/staking/contracts/src/staking_pools/MixinCumulativeRewards.sol
@@ -68,15 +68,10 @@ contract MixinCumulativeRewards is
     {
         uint256 currentEpoch_ = currentEpoch;
         _cumulativeRewardsByPool[poolId][currentEpoch_] = value;
-
-        // Check if we should do any work
-        uint256 currentMostRecentEpoch = _cumulativeRewardsByPoolLastStored[poolId];
-        if (currentEpoch_ == currentMostRecentEpoch) {
-            return;
-        }
-
+        
         // Update state to reflect the most recent cumulative reward
-        assert(currentEpoch_ > currentMostRecentEpoch);
+        uint256 currentMostRecentEpoch = _cumulativeRewardsByPoolLastStored[poolId];
+        assert(currentEpoch_ >= currentMostRecentEpoch);
         _cumulativeRewardsByPoolLastStored[poolId] = currentEpoch_;
     }
 

From 5b77e2c8aca435d6f9aa52ab1157f807f812a775 Mon Sep 17 00:00:00 2001
From: Lawrence Forman <lawrence@0xproject.com>
Date: Wed, 25 Sep 2019 15:29:22 -0400
Subject: [PATCH 8/9] `@0x/contracts-staking`: Fix stake accounting.

---
 .../contracts/src/stake/MixinStake.sol        | 26 +++++++++++++------
 .../staking_pools/MixinStakingPoolRewards.sol | 15 +++++++----
 .../contracts/test/TestDelegatorRewards.sol   | 14 +++++++---
 .../test/cumulative_reward_tracking_test.ts   | 24 ++++++++---------
 4 files changed, 50 insertions(+), 29 deletions(-)

diff --git a/contracts/staking/contracts/src/stake/MixinStake.sol b/contracts/staking/contracts/src/stake/MixinStake.sol
index a77350fbd5..930003161a 100644
--- a/contracts/staking/contracts/src/stake/MixinStake.sol
+++ b/contracts/staking/contracts/src/stake/MixinStake.sol
@@ -187,10 +187,9 @@ contract MixinStake is
         // Sanity check the pool we're delegating to exists.
         _assertStakingPoolExists(poolId);
 
-        _withdrawAndSyncDelegatorRewards(
-            poolId,
-            staker
-        );
+        // Cache amount delegated to pool by staker.
+        IStructs.StoredBalance memory initDelegatedStakeToPoolByOwner =
+            _loadUnsyncedBalance(_delegatedStakeToPoolByOwner[staker][poolId]);
 
         // Increment how much stake the staker has delegated to the input pool.
         _increaseNextBalance(
@@ -200,6 +199,12 @@ contract MixinStake is
 
         // Increment how much stake has been delegated to pool.
         _increaseNextBalance(_delegatedStakeByPoolId[poolId], amount);
+
+        _withdrawAndSyncDelegatorRewards(
+            poolId,
+            staker,
+            initDelegatedStakeToPoolByOwner
+        );
     }
 
     /// @dev Un-Delegates a owners stake from a staking pool.
@@ -216,10 +221,9 @@ contract MixinStake is
         // sanity check the pool we're undelegating from exists
         _assertStakingPoolExists(poolId);
 
-        _withdrawAndSyncDelegatorRewards(
-            poolId,
-            staker
-        );
+        // Cache amount delegated to pool by staker.
+        IStructs.StoredBalance memory initDelegatedStakeToPoolByOwner =
+            _loadUnsyncedBalance(_delegatedStakeToPoolByOwner[staker][poolId]);
 
         // decrement how much stake the staker has delegated to the input pool
         _decreaseNextBalance(
@@ -229,6 +233,12 @@ contract MixinStake is
 
         // decrement how much stake has been delegated to pool
         _decreaseNextBalance(_delegatedStakeByPoolId[poolId], amount);
+
+        _withdrawAndSyncDelegatorRewards(
+            poolId,
+            staker,
+            initDelegatedStakeToPoolByOwner
+        );
     }
 
     /// @dev Returns a storage pointer to a user's stake in a given status.
diff --git a/contracts/staking/contracts/src/staking_pools/MixinStakingPoolRewards.sol b/contracts/staking/contracts/src/staking_pools/MixinStakingPoolRewards.sol
index 99274b54e8..7d70b50d72 100644
--- a/contracts/staking/contracts/src/staking_pools/MixinStakingPoolRewards.sol
+++ b/contracts/staking/contracts/src/staking_pools/MixinStakingPoolRewards.sol
@@ -46,7 +46,8 @@ contract MixinStakingPoolRewards is
 
         _withdrawAndSyncDelegatorRewards(
             poolId,
-            member
+            member,
+            _loadUnsyncedBalance(_delegatedStakeToPoolByOwner[member][poolId])
         );
 
         // Update stored balance with synchronized version; this prevents
@@ -103,6 +104,7 @@ contract MixinStakingPoolRewards is
         return _computeDelegatorReward(
             poolId,
             member,
+            _loadUnsyncedBalance(_delegatedStakeToPoolByOwner[member][poolId]),
             unfinalizedMembersReward,
             unfinalizedMembersStake
         );
@@ -112,9 +114,12 @@ contract MixinStakingPoolRewards is
     ///      withdrawing rewards and adding/removing dependencies on cumulative rewards.
     /// @param poolId Unique id of pool.
     /// @param member of the pool.
+    /// @param unsyncedStake The member's unsynced delegated balance at the
+    ///        beginning of this transaction.
     function _withdrawAndSyncDelegatorRewards(
         bytes32 poolId,
-        address member
+        address member,
+        IStructs.StoredBalance memory unsyncedStake
     )
         internal
     {
@@ -125,6 +130,7 @@ contract MixinStakingPoolRewards is
         uint256 balance = _computeDelegatorReward(
             poolId,
             member,
+            unsyncedStake,
             // No unfinalized values because we ensured the pool is already
             // finalized.
             0,
@@ -247,12 +253,14 @@ contract MixinStakingPoolRewards is
     /// @dev Computes the reward balance in ETH of a specific member of a pool.
     /// @param poolId Unique id of pool.
     /// @param member of the pool.
+    /// @param unsyncedStake Unsynced delegated stake to pool by staker
     /// @param unfinalizedMembersReward Unfinalized total members reward (if any).
     /// @param unfinalizedMembersStake Unfinalized total members stake (if any).
     /// @return reward Balance in WETH.
     function _computeDelegatorReward(
         bytes32 poolId,
         address member,
+        IStructs.StoredBalance memory unsyncedStake,
         uint256 unfinalizedMembersReward,
         uint256 unfinalizedMembersStake
     )
@@ -267,9 +275,6 @@ contract MixinStakingPoolRewards is
             return 0;
         }
 
-        IStructs.StoredBalance memory unsyncedStake =
-            _loadUnsyncedBalance(_delegatedStakeToPoolByOwner[member][poolId]);
-
         // There can be no rewards if the last epoch when stake was synced is
         // equal to the current epoch, because all prior rewards, including
         // rewards finalized this epoch have been claimed.
diff --git a/contracts/staking/contracts/test/TestDelegatorRewards.sol b/contracts/staking/contracts/test/TestDelegatorRewards.sol
index 2c4aa80c7a..a782d63a4f 100644
--- a/contracts/staking/contracts/test/TestDelegatorRewards.sol
+++ b/contracts/staking/contracts/test/TestDelegatorRewards.sol
@@ -86,7 +86,7 @@ contract TestDelegatorRewards is
         _poolById[poolId].operator = operatorAddress;
         _setOperatorShare(poolId, operatorReward, membersReward);
         _initGenesisCumulativeRewards(poolId);
-        
+
         _syncPoolRewards(
             poolId,
             operatorReward + membersReward,
@@ -110,6 +110,7 @@ contract TestDelegatorRewards is
         external
     {
         _initGenesisCumulativeRewards(poolId);
+        IStructs.StoredBalance memory initialStake = _delegatedStakeToPoolByOwner[delegator][poolId];
         IStructs.StoredBalance storage _stake = _delegatedStakeToPoolByOwner[delegator][poolId];
         _stake.isInitialized = true;
         _stake.currentEpochBalance += uint96(stake);
@@ -117,7 +118,8 @@ contract TestDelegatorRewards is
         _stake.currentEpoch = uint32(currentEpoch);
         _withdrawAndSyncDelegatorRewards(
             poolId,
-            delegator
+            delegator,
+            initialStake
         );
     }
 
@@ -132,6 +134,7 @@ contract TestDelegatorRewards is
         external
     {
         _initGenesisCumulativeRewards(poolId);
+        IStructs.StoredBalance memory initialStake = _delegatedStakeToPoolByOwner[delegator][poolId];
         IStructs.StoredBalance storage _stake = _delegatedStakeToPoolByOwner[delegator][poolId];
         if (_stake.currentEpoch < currentEpoch) {
             _stake.currentEpochBalance = _stake.nextEpochBalance;
@@ -141,7 +144,8 @@ contract TestDelegatorRewards is
         _stake.currentEpoch = uint32(currentEpoch);
         _withdrawAndSyncDelegatorRewards(
             poolId,
-            delegator
+            delegator,
+            initialStake
         );
     }
 
@@ -156,6 +160,7 @@ contract TestDelegatorRewards is
         external
     {
         _initGenesisCumulativeRewards(poolId);
+        IStructs.StoredBalance memory initialStake = _delegatedStakeToPoolByOwner[delegator][poolId];
         IStructs.StoredBalance storage _stake = _delegatedStakeToPoolByOwner[delegator][poolId];
         if (_stake.currentEpoch < currentEpoch) {
             _stake.currentEpochBalance = _stake.nextEpochBalance;
@@ -165,7 +170,8 @@ contract TestDelegatorRewards is
         _stake.currentEpoch = uint32(currentEpoch);
         _withdrawAndSyncDelegatorRewards(
             poolId,
-            delegator
+            delegator,
+            initialStake
         );
     }
 
diff --git a/contracts/staking/test/cumulative_reward_tracking_test.ts b/contracts/staking/test/cumulative_reward_tracking_test.ts
index 5e1df454f4..c4ba1d3235 100644
--- a/contracts/staking/test/cumulative_reward_tracking_test.ts
+++ b/contracts/staking/test/cumulative_reward_tracking_test.ts
@@ -39,7 +39,7 @@ blockchainTests.resets('Cumulative Reward Tracking', env => {
             await simulation.runTestAsync(
                 [TestAction.Finalize],
                 [TestAction.CreatePool],
-                [{ event: 'SetCumulativeReward', epoch: 1 }, { event: 'SetMostRecentCumulativeReward', epoch: 1 }],
+                [{ event: 'SetCumulativeReward', epoch: 1 }],
             );
         });
         it('delegating in the same epoch pool is created', async () => {
@@ -86,7 +86,7 @@ blockchainTests.resets('Cumulative Reward Tracking', env => {
                     // Unsets the CR for epoch 0
                     TestAction.Delegate,
                 ],
-                [{ event: 'SetCumulativeReward', epoch: 1 }, { event: 'SetMostRecentCumulativeReward', epoch: 1 }],
+                [{ event: 'SetCumulativeReward', epoch: 1 }],
             );
         });
         it('re-delegating in a new epoch', async () => {
@@ -105,7 +105,7 @@ blockchainTests.resets('Cumulative Reward Tracking', env => {
                     // Sets MRCR to epoch 1
                     TestAction.Delegate,
                 ],
-                [{ event: 'SetCumulativeReward', epoch: 1 }, { event: 'SetMostRecentCumulativeReward', epoch: 1 }],
+                [{ event: 'SetCumulativeReward', epoch: 1 }],
             );
         });
         it('delegating in epoch 1 then again in epoch 2', async () => {
@@ -128,7 +128,7 @@ blockchainTests.resets('Cumulative Reward Tracking', env => {
                     // Clears CR for epoch 1
                     TestAction.Delegate,
                 ],
-                [{ event: 'SetCumulativeReward', epoch: 2 }, { event: 'SetMostRecentCumulativeReward', epoch: 2 }],
+                [{ event: 'SetCumulativeReward', epoch: 2 } ],
             );
         });
         it('delegate in epoch 1 then undelegate in epoch 2', async () => {
@@ -152,7 +152,7 @@ blockchainTests.resets('Cumulative Reward Tracking', env => {
                     // Clear CR for epoch 1
                     TestAction.Undelegate,
                 ],
-                [{ event: 'SetCumulativeReward', epoch: 2 }, { event: 'SetMostRecentCumulativeReward', epoch: 2 }],
+                [{ event: 'SetCumulativeReward', epoch: 2 } ],
             );
         });
         it('delegate in epoch 0 and epoch 1, then undelegate half in epoch 2', async () => {
@@ -181,7 +181,7 @@ blockchainTests.resets('Cumulative Reward Tracking', env => {
                     // Clears CR for epoch 1
                     TestAction.Undelegate,
                 ],
-                [{ event: 'SetCumulativeReward', epoch: 2 }, { event: 'SetMostRecentCumulativeReward', epoch: 2 }],
+                [{ event: 'SetCumulativeReward', epoch: 2 } ],
             );
         });
         it('delegate in epoch 1 and 2 then again in 3', async () => {
@@ -210,7 +210,7 @@ blockchainTests.resets('Cumulative Reward Tracking', env => {
                     // Clears CR for epoch 1
                     TestAction.Delegate,
                 ],
-                [{ event: 'SetCumulativeReward', epoch: 2 }, { event: 'SetMostRecentCumulativeReward', epoch: 2 }],
+                [{ event: 'SetCumulativeReward', epoch: 2 } ],
             );
         });
         it('delegate in epoch 0, earn reward in epoch 1', async () => {
@@ -233,7 +233,7 @@ blockchainTests.resets('Cumulative Reward Tracking', env => {
                     // Sets MRCR to epoch 2
                     TestAction.Finalize,
                 ],
-                [{ event: 'SetCumulativeReward', epoch: 2 }, { event: 'SetMostRecentCumulativeReward', epoch: 2 }],
+                [{ event: 'SetCumulativeReward', epoch: 2 } ],
             );
         });
         it('delegate in epoch 0, epoch 2, earn reward in epoch 3, then delegate', async () => {
@@ -341,7 +341,7 @@ blockchainTests.resets('Cumulative Reward Tracking', env => {
                     // Clears CR for epoch 1
                     TestAction.Delegate,
                 ],
-                [{ event: 'SetCumulativeReward', epoch: 4 }, { event: 'SetMostRecentCumulativeReward', epoch: 4 }],
+                [{ event: 'SetCumulativeReward', epoch: 4 } ],
             );
         });
         it('earn reward in epoch 1 with no stake, then delegate', async () => {
@@ -362,7 +362,7 @@ blockchainTests.resets('Cumulative Reward Tracking', env => {
                     // Creates CR for epoch 2
                     TestAction.Delegate,
                 ],
-                [{ event: 'SetCumulativeReward', epoch: 1 }, { event: 'SetMostRecentCumulativeReward', epoch: 1 }],
+                [{ event: 'SetCumulativeReward', epoch: 1 }],
             );
         });
         it('delegate in epoch 1, 3, then delegate in epoch 4', async () => {
@@ -397,7 +397,7 @@ blockchainTests.resets('Cumulative Reward Tracking', env => {
                     // Creates CR for epoch 5
                     TestAction.Delegate,
                 ],
-                [{ event: 'SetCumulativeReward', epoch: 4 }, { event: 'SetMostRecentCumulativeReward', epoch: 4 }],
+                [{ event: 'SetCumulativeReward', epoch: 4 } ],
             );
         });
         it('delegate in epoch 1, then epoch 3', async () => {
@@ -425,7 +425,7 @@ blockchainTests.resets('Cumulative Reward Tracking', env => {
                     // Clears CR for epoch 2
                     TestAction.Delegate,
                 ],
-                [{ event: 'SetCumulativeReward', epoch: 3 }, { event: 'SetMostRecentCumulativeReward', epoch: 3 }],
+                [{ event: 'SetCumulativeReward', epoch: 3 } ],
             );
         });
     });

From f925c353447a5b82df07e0cb2ada65b3fe11941e Mon Sep 17 00:00:00 2001
From: Lawrence Forman <lawrence@0xproject.com>
Date: Wed, 25 Sep 2019 16:34:06 -0400
Subject: [PATCH 9/9] `@0x/contracts-staking: Always do
 `_withdrawAndSyncDelegatorRewards()` before staking operations and always add
 a CR (if unset) in `_withdrawSyncDelegatorRewards()`.

---
 .../contracts/src/stake/MixinStake.sol        | 26 +++-----
 .../staking_pools/MixinStakingPoolRewards.sol | 61 ++++---------------
 .../contracts/test/TestDelegatorRewards.sol   | 28 ++++-----
 .../contracts/test/TestStakingNoWETH.sol      |  2 +-
 .../test/cumulative_reward_tracking_test.ts   | 16 ++---
 5 files changed, 42 insertions(+), 91 deletions(-)

diff --git a/contracts/staking/contracts/src/stake/MixinStake.sol b/contracts/staking/contracts/src/stake/MixinStake.sol
index 930003161a..a77350fbd5 100644
--- a/contracts/staking/contracts/src/stake/MixinStake.sol
+++ b/contracts/staking/contracts/src/stake/MixinStake.sol
@@ -187,9 +187,10 @@ contract MixinStake is
         // Sanity check the pool we're delegating to exists.
         _assertStakingPoolExists(poolId);
 
-        // Cache amount delegated to pool by staker.
-        IStructs.StoredBalance memory initDelegatedStakeToPoolByOwner =
-            _loadUnsyncedBalance(_delegatedStakeToPoolByOwner[staker][poolId]);
+        _withdrawAndSyncDelegatorRewards(
+            poolId,
+            staker
+        );
 
         // Increment how much stake the staker has delegated to the input pool.
         _increaseNextBalance(
@@ -199,12 +200,6 @@ contract MixinStake is
 
         // Increment how much stake has been delegated to pool.
         _increaseNextBalance(_delegatedStakeByPoolId[poolId], amount);
-
-        _withdrawAndSyncDelegatorRewards(
-            poolId,
-            staker,
-            initDelegatedStakeToPoolByOwner
-        );
     }
 
     /// @dev Un-Delegates a owners stake from a staking pool.
@@ -221,9 +216,10 @@ contract MixinStake is
         // sanity check the pool we're undelegating from exists
         _assertStakingPoolExists(poolId);
 
-        // Cache amount delegated to pool by staker.
-        IStructs.StoredBalance memory initDelegatedStakeToPoolByOwner =
-            _loadUnsyncedBalance(_delegatedStakeToPoolByOwner[staker][poolId]);
+        _withdrawAndSyncDelegatorRewards(
+            poolId,
+            staker
+        );
 
         // decrement how much stake the staker has delegated to the input pool
         _decreaseNextBalance(
@@ -233,12 +229,6 @@ contract MixinStake is
 
         // decrement how much stake has been delegated to pool
         _decreaseNextBalance(_delegatedStakeByPoolId[poolId], amount);
-
-        _withdrawAndSyncDelegatorRewards(
-            poolId,
-            staker,
-            initDelegatedStakeToPoolByOwner
-        );
     }
 
     /// @dev Returns a storage pointer to a user's stake in a given status.
diff --git a/contracts/staking/contracts/src/staking_pools/MixinStakingPoolRewards.sol b/contracts/staking/contracts/src/staking_pools/MixinStakingPoolRewards.sol
index 7d70b50d72..153481bfa0 100644
--- a/contracts/staking/contracts/src/staking_pools/MixinStakingPoolRewards.sol
+++ b/contracts/staking/contracts/src/staking_pools/MixinStakingPoolRewards.sol
@@ -46,8 +46,7 @@ contract MixinStakingPoolRewards is
 
         _withdrawAndSyncDelegatorRewards(
             poolId,
-            member,
-            _loadUnsyncedBalance(_delegatedStakeToPoolByOwner[member][poolId])
+            member
         );
 
         // Update stored balance with synchronized version; this prevents
@@ -104,7 +103,6 @@ contract MixinStakingPoolRewards is
         return _computeDelegatorReward(
             poolId,
             member,
-            _loadUnsyncedBalance(_delegatedStakeToPoolByOwner[member][poolId]),
             unfinalizedMembersReward,
             unfinalizedMembersStake
         );
@@ -114,12 +112,9 @@ contract MixinStakingPoolRewards is
     ///      withdrawing rewards and adding/removing dependencies on cumulative rewards.
     /// @param poolId Unique id of pool.
     /// @param member of the pool.
-    /// @param unsyncedStake The member's unsynced delegated balance at the
-    ///        beginning of this transaction.
     function _withdrawAndSyncDelegatorRewards(
         bytes32 poolId,
-        address member,
-        IStructs.StoredBalance memory unsyncedStake
+        address member
     )
         internal
     {
@@ -130,7 +125,6 @@ contract MixinStakingPoolRewards is
         uint256 balance = _computeDelegatorReward(
             poolId,
             member,
-            unsyncedStake,
             // No unfinalized values because we ensured the pool is already
             // finalized.
             0,
@@ -146,12 +140,13 @@ contract MixinStakingPoolRewards is
             getWethContract().transfer(member, balance);
         }
 
-        // Add dependencies on cumulative rewards for this epoch and the next
-        // epoch, if necessary.
-        _setCumulativeRewardDependenciesForDelegator(
-            poolId,
-            member
-        );
+        // Add a cumulative reward entry for this epoch.
+        if (!_isCumulativeRewardSet(_cumulativeRewardsByPool[poolId][currentEpoch])) {
+            _forceSetCumulativeReward(
+                poolId,
+                _getMostRecentCumulativeReward(poolId)
+            );
+        }
     }
 
     /// @dev Handles a pool's reward at the current epoch.
@@ -253,14 +248,12 @@ contract MixinStakingPoolRewards is
     /// @dev Computes the reward balance in ETH of a specific member of a pool.
     /// @param poolId Unique id of pool.
     /// @param member of the pool.
-    /// @param unsyncedStake Unsynced delegated stake to pool by staker
     /// @param unfinalizedMembersReward Unfinalized total members reward (if any).
     /// @param unfinalizedMembersStake Unfinalized total members stake (if any).
     /// @return reward Balance in WETH.
     function _computeDelegatorReward(
         bytes32 poolId,
         address member,
-        IStructs.StoredBalance memory unsyncedStake,
         uint256 unfinalizedMembersReward,
         uint256 unfinalizedMembersStake
     )
@@ -275,6 +268,9 @@ contract MixinStakingPoolRewards is
             return 0;
         }
 
+        IStructs.StoredBalance memory unsyncedStake =
+            _loadUnsyncedBalance(_delegatedStakeToPoolByOwner[member][poolId]);
+
         // There can be no rewards if the last epoch when stake was synced is
         // equal to the current epoch, because all prior rewards, including
         // rewards finalized this epoch have been claimed.
@@ -357,39 +353,6 @@ contract MixinStakingPoolRewards is
         );
     }
 
-    /// @dev Adds or removes cumulative reward dependencies for a delegator.
-    ///      A delegator always depends on the cumulative reward for the current
-    ///      and next epoch, if they would still have stake in the next epoch.
-    /// @param poolId Unique id of pool.
-    /// @param member of the pool.
-    function _setCumulativeRewardDependenciesForDelegator(
-        bytes32 poolId,
-        address member
-    )
-        private
-    {
-        IStructs.StoredBalance memory finalDelegatedStake =
-            _loadSyncedBalance(_delegatedStakeToPoolByOwner[member][poolId]);
-
-        // The delegator depends on the Cumulative Reward for this epoch
-        // only if they are currently staked or will be staked next epoch.
-        if (finalDelegatedStake.currentEpochBalance == 0 && finalDelegatedStake.nextEpochBalance == 0) {
-            return;
-        }
-
-        // Get the most recent cumulative reward, which will serve as a
-        // reference point when updating dependencies
-        IStructs.Fraction memory mostRecentCumulativeReward = _getMostRecentCumulativeReward(poolId);
-
-        // Delegator depends on the Cumulative Reward for this epoch - ensure it is set.
-        if (!_isCumulativeRewardSet(_cumulativeRewardsByPool[poolId][finalDelegatedStake.currentEpoch])) {
-            _forceSetCumulativeReward(
-                poolId,
-                mostRecentCumulativeReward
-            );
-        }
-    }
-
     /// @dev Increases rewards for a pool.
     /// @param poolId Unique id of pool.
     /// @param amount Amount to increment rewards by.
diff --git a/contracts/staking/contracts/test/TestDelegatorRewards.sol b/contracts/staking/contracts/test/TestDelegatorRewards.sol
index a782d63a4f..5e86e001bd 100644
--- a/contracts/staking/contracts/test/TestDelegatorRewards.sol
+++ b/contracts/staking/contracts/test/TestDelegatorRewards.sol
@@ -110,7 +110,10 @@ contract TestDelegatorRewards is
         external
     {
         _initGenesisCumulativeRewards(poolId);
-        IStructs.StoredBalance memory initialStake = _delegatedStakeToPoolByOwner[delegator][poolId];
+        _withdrawAndSyncDelegatorRewards(
+            poolId,
+            delegator
+        );
         IStructs.StoredBalance storage _stake = _delegatedStakeToPoolByOwner[delegator][poolId];
         _stake.isInitialized = true;
         _stake.currentEpochBalance += uint96(stake);
@@ -118,8 +121,7 @@ contract TestDelegatorRewards is
         _stake.currentEpoch = uint32(currentEpoch);
         _withdrawAndSyncDelegatorRewards(
             poolId,
-            delegator,
-            initialStake
+            delegator
         );
     }
 
@@ -134,7 +136,10 @@ contract TestDelegatorRewards is
         external
     {
         _initGenesisCumulativeRewards(poolId);
-        IStructs.StoredBalance memory initialStake = _delegatedStakeToPoolByOwner[delegator][poolId];
+        _withdrawAndSyncDelegatorRewards(
+            poolId,
+            delegator
+        );
         IStructs.StoredBalance storage _stake = _delegatedStakeToPoolByOwner[delegator][poolId];
         if (_stake.currentEpoch < currentEpoch) {
             _stake.currentEpochBalance = _stake.nextEpochBalance;
@@ -142,11 +147,6 @@ contract TestDelegatorRewards is
         _stake.isInitialized = true;
         _stake.nextEpochBalance += uint96(stake);
         _stake.currentEpoch = uint32(currentEpoch);
-        _withdrawAndSyncDelegatorRewards(
-            poolId,
-            delegator,
-            initialStake
-        );
     }
 
     /// @dev Clear stake that will occur in the next epoch
@@ -160,7 +160,10 @@ contract TestDelegatorRewards is
         external
     {
         _initGenesisCumulativeRewards(poolId);
-        IStructs.StoredBalance memory initialStake = _delegatedStakeToPoolByOwner[delegator][poolId];
+        _withdrawAndSyncDelegatorRewards(
+            poolId,
+            delegator
+        );
         IStructs.StoredBalance storage _stake = _delegatedStakeToPoolByOwner[delegator][poolId];
         if (_stake.currentEpoch < currentEpoch) {
             _stake.currentEpochBalance = _stake.nextEpochBalance;
@@ -168,11 +171,6 @@ contract TestDelegatorRewards is
         _stake.isInitialized = true;
         _stake.nextEpochBalance -= uint96(stake);
         _stake.currentEpoch = uint32(currentEpoch);
-        _withdrawAndSyncDelegatorRewards(
-            poolId,
-            delegator,
-            initialStake
-        );
     }
 
     // solhint-disable no-simple-event-func-name
diff --git a/contracts/staking/contracts/test/TestStakingNoWETH.sol b/contracts/staking/contracts/test/TestStakingNoWETH.sol
index 77375f59b9..e176f326aa 100644
--- a/contracts/staking/contracts/test/TestStakingNoWETH.sol
+++ b/contracts/staking/contracts/test/TestStakingNoWETH.sol
@@ -22,7 +22,7 @@ pragma experimental ABIEncoderV2;
 import "../src/Staking.sol";
 
 
-// solhint-disable no-empty-blocks
+// solhint-disable no-empty-blocks,no-simple-event-func-name
 /// @dev A version of the staking contract with WETH-related functions
 ///      overridden to do nothing.
 contract TestStakingNoWETH is
diff --git a/contracts/staking/test/cumulative_reward_tracking_test.ts b/contracts/staking/test/cumulative_reward_tracking_test.ts
index c4ba1d3235..b2b4e360fc 100644
--- a/contracts/staking/test/cumulative_reward_tracking_test.ts
+++ b/contracts/staking/test/cumulative_reward_tracking_test.ts
@@ -128,7 +128,7 @@ blockchainTests.resets('Cumulative Reward Tracking', env => {
                     // Clears CR for epoch 1
                     TestAction.Delegate,
                 ],
-                [{ event: 'SetCumulativeReward', epoch: 2 } ],
+                [{ event: 'SetCumulativeReward', epoch: 2 }],
             );
         });
         it('delegate in epoch 1 then undelegate in epoch 2', async () => {
@@ -152,7 +152,7 @@ blockchainTests.resets('Cumulative Reward Tracking', env => {
                     // Clear CR for epoch 1
                     TestAction.Undelegate,
                 ],
-                [{ event: 'SetCumulativeReward', epoch: 2 } ],
+                [{ event: 'SetCumulativeReward', epoch: 2 }],
             );
         });
         it('delegate in epoch 0 and epoch 1, then undelegate half in epoch 2', async () => {
@@ -181,7 +181,7 @@ blockchainTests.resets('Cumulative Reward Tracking', env => {
                     // Clears CR for epoch 1
                     TestAction.Undelegate,
                 ],
-                [{ event: 'SetCumulativeReward', epoch: 2 } ],
+                [{ event: 'SetCumulativeReward', epoch: 2 }],
             );
         });
         it('delegate in epoch 1 and 2 then again in 3', async () => {
@@ -210,7 +210,7 @@ blockchainTests.resets('Cumulative Reward Tracking', env => {
                     // Clears CR for epoch 1
                     TestAction.Delegate,
                 ],
-                [{ event: 'SetCumulativeReward', epoch: 2 } ],
+                [{ event: 'SetCumulativeReward', epoch: 2 }],
             );
         });
         it('delegate in epoch 0, earn reward in epoch 1', async () => {
@@ -233,7 +233,7 @@ blockchainTests.resets('Cumulative Reward Tracking', env => {
                     // Sets MRCR to epoch 2
                     TestAction.Finalize,
                 ],
-                [{ event: 'SetCumulativeReward', epoch: 2 } ],
+                [{ event: 'SetCumulativeReward', epoch: 2 }],
             );
         });
         it('delegate in epoch 0, epoch 2, earn reward in epoch 3, then delegate', async () => {
@@ -341,7 +341,7 @@ blockchainTests.resets('Cumulative Reward Tracking', env => {
                     // Clears CR for epoch 1
                     TestAction.Delegate,
                 ],
-                [{ event: 'SetCumulativeReward', epoch: 4 } ],
+                [{ event: 'SetCumulativeReward', epoch: 4 }],
             );
         });
         it('earn reward in epoch 1 with no stake, then delegate', async () => {
@@ -397,7 +397,7 @@ blockchainTests.resets('Cumulative Reward Tracking', env => {
                     // Creates CR for epoch 5
                     TestAction.Delegate,
                 ],
-                [{ event: 'SetCumulativeReward', epoch: 4 } ],
+                [{ event: 'SetCumulativeReward', epoch: 4 }],
             );
         });
         it('delegate in epoch 1, then epoch 3', async () => {
@@ -425,7 +425,7 @@ blockchainTests.resets('Cumulative Reward Tracking', env => {
                     // Clears CR for epoch 2
                     TestAction.Delegate,
                 ],
-                [{ event: 'SetCumulativeReward', epoch: 3 } ],
+                [{ event: 'SetCumulativeReward', epoch: 3 }],
             );
         });
     });