Merge pull request #1036 from 0xProject/fix/contracts/calculateFillResults

Making rounding consistent in calculateFillResults

2 files changed, 12 insertions, 9 deletions

diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinExchangeCore.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinExchangeCore.sol
index 64b1f7665..ff908917d 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/MixinExchangeCore.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinExchangeCore.sol
@@ -459,8 +459,8 @@ contract MixinExchangeCore is
             order.makerAssetAmount
         );
         fillResults.makerFeePaid = safeGetPartialAmountFloor(
-            takerAssetFilledAmount,
-            order.takerAssetAmount,
+            fillResults.makerAssetFilledAmount,
+            order.makerAssetAmount,
             order.makerFee
         );
         fillResults.takerFeePaid = safeGetPartialAmountFloor(
diff --git a/packages/contracts/test/exchange/internal.ts b/packages/contracts/test/exchange/internal.ts
index c5d2fc58f..dc2c5fbe0 100644
--- a/packages/contracts/test/exchange/internal.ts
+++ b/packages/contracts/test/exchange/internal.ts
@@ -221,16 +221,19 @@ describe('Exchange core internal functions', () => {
             // in any mathematical operation in either the reference TypeScript
             // implementation or the Solidity implementation of
             // calculateFillResults.
+            const makerAssetFilledAmount = await referenceSafeGetPartialAmountFloorAsync(
+                takerAssetFilledAmount,
+                orderTakerAssetAmount,
+                otherAmount,
+            );
+            const order = makeOrder(otherAmount, orderTakerAssetAmount, otherAmount, otherAmount);
+            const orderMakerAssetAmount = order.makerAssetAmount;
             return {
-                makerAssetFilledAmount: await referenceSafeGetPartialAmountFloorAsync(
-                    takerAssetFilledAmount,
-                    orderTakerAssetAmount,
-                    otherAmount,
-                ),
+                makerAssetFilledAmount,
                 takerAssetFilledAmount,
                 makerFeePaid: await referenceSafeGetPartialAmountFloorAsync(
-                    takerAssetFilledAmount,
-                    orderTakerAssetAmount,
+                    makerAssetFilledAmount,
+                    orderMakerAssetAmount,
                     otherAmount,
                 ),
                 takerFeePaid: await referenceSafeGetPartialAmountFloorAsync(