Fix incorrect affiliate fee calculations and associated tests

2 files changed, 20 insertions, 14 deletions

diff --git a/packages/asset-buyer/src/utils/buy_quote_calculator.ts b/packages/asset-buyer/src/utils/buy_quote_calculator.ts
index cb0fd128c..a1d334eef 100644
--- a/packages/asset-buyer/src/utils/buy_quote_calculator.ts
+++ b/packages/asset-buyer/src/utils/buy_quote_calculator.ts
@@ -72,7 +72,6 @@ export const buyQuoteCalculator = {
             assetBuyAmount,
             feePercentage,
         );
-
         return {
             assetData,
             orders: resultOrders,
@@ -98,13 +97,14 @@ function calculateQuoteInfo(
     );
     // find the total eth needed to buy fees
     const ethAmountToBuyFees = findEthAmountNeededToBuyFees(feeOrdersAndFillableAmounts, zrxAmountToBuyAsset);
-    const ethAmountBeforeAffiliateFee = ethAmountToBuyAsset.plus(ethAmountToBuyFees);
-    const totalEthAmount = ethAmountBeforeAffiliateFee.mul(feePercentage + 1);
+    const affiliateFeeEthAmount = ethAmountToBuyAsset.mul(feePercentage);
+    const totalEthAmountWithoutAffiliateFee = ethAmountToBuyAsset.plus(ethAmountToBuyFees);
+    const totalEthAmount = totalEthAmountWithoutAffiliateFee.plus(affiliateFeeEthAmount);
     // divide into the assetBuyAmount in order to find rate of makerAsset / WETH
-    const ethPerAssetPrice = ethAmountBeforeAffiliateFee.div(assetBuyAmount);
+    const ethPerAssetPrice = totalEthAmountWithoutAffiliateFee.div(assetBuyAmount);
     return {
         totalEthAmount,
-        feeEthAmount: totalEthAmount.minus(ethAmountBeforeAffiliateFee),
+        feeEthAmount: affiliateFeeEthAmount,
         ethPerAssetPrice,
     };
 }
diff --git a/packages/asset-buyer/test/buy_quote_calculator_test.ts b/packages/asset-buyer/test/buy_quote_calculator_test.ts
index b987b45a8..fda6958cd 100644
--- a/packages/asset-buyer/test/buy_quote_calculator_test.ts
+++ b/packages/asset-buyer/test/buy_quote_calculator_test.ts
@@ -103,9 +103,11 @@ describe('buyQuoteCalculator', () => {
             expect(buyQuote.feeOrders).to.deep.equal([smallFeeOrderAndFillableAmount.orders[0]]);
             // test if rates are correct
             // 50 eth to fill the first order + 100 eth for fees
-            const expectedFillEthAmount = new BigNumber(150);
-            const expectedTotalEthAmount = expectedFillEthAmount.mul(feePercentage + 1);
-            const expectedFeeEthAmount = expectedTotalEthAmount.minus(expectedFillEthAmount);
+            const expectedEthAmountForAsset = new BigNumber(50);
+            const expectedEthAmountForZrxFees = new BigNumber(100);
+            const expectedFillEthAmount = expectedEthAmountForAsset.plus(expectedEthAmountForZrxFees);
+            const expectedFeeEthAmount = expectedEthAmountForAsset.mul(feePercentage);
+            const expectedTotalEthAmount = expectedFillEthAmount.plus(expectedFeeEthAmount);
             const expectedEthPerAssetPrice = expectedFillEthAmount.div(assetBuyAmount);
             expect(buyQuote.bestCaseQuoteInfo.feeEthAmount).to.bignumber.equal(expectedFeeEthAmount);
             expect(buyQuote.bestCaseQuoteInfo.totalEthAmount).to.bignumber.equal(expectedTotalEthAmount);
@@ -138,17 +140,21 @@ describe('buyQuoteCalculator', () => {
             expect(buyQuote.feeOrders).to.deep.equal(allFeeOrdersAndFillableAmounts.orders);
             // test if rates are correct
             // 50 eth to fill the first order + 100 eth for fees
-            const expectedFillEthAmount = new BigNumber(150);
-            const expectedTotalEthAmount = expectedFillEthAmount.mul(feePercentage + 1);
-            const expectedFeeEthAmount = expectedTotalEthAmount.minus(expectedFillEthAmount);
+            const expectedEthAmountForAsset = new BigNumber(50);
+            const expectedEthAmountForZrxFees = new BigNumber(100);
+            const expectedFillEthAmount = expectedEthAmountForAsset.plus(expectedEthAmountForZrxFees);
+            const expectedFeeEthAmount = expectedEthAmountForAsset.mul(feePercentage);
+            const expectedTotalEthAmount = expectedFillEthAmount.plus(expectedFeeEthAmount);
             const expectedEthPerAssetPrice = expectedFillEthAmount.div(assetBuyAmount);
             expect(buyQuote.bestCaseQuoteInfo.feeEthAmount).to.bignumber.equal(expectedFeeEthAmount);
             expect(buyQuote.bestCaseQuoteInfo.totalEthAmount).to.bignumber.equal(expectedTotalEthAmount);
             expect(buyQuote.bestCaseQuoteInfo.ethPerAssetPrice).to.bignumber.equal(expectedEthPerAssetPrice);
             // 100 eth to fill the first order + 200 eth for fees
-            const expectedWorstFillEthAmount = new BigNumber(300);
-            const expectedWorstTotalEthAmount = expectedWorstFillEthAmount.mul(feePercentage + 1);
-            const expectedWorstFeeEthAmount = expectedWorstTotalEthAmount.minus(expectedWorstFillEthAmount);
+            const expectedWorstEthAmountForAsset = new BigNumber(100);
+            const expectedWorstEthAmountForZrxFees = new BigNumber(200);
+            const expectedWorstFillEthAmount = expectedWorstEthAmountForAsset.plus(expectedWorstEthAmountForZrxFees);
+            const expectedWorstFeeEthAmount = expectedWorstEthAmountForAsset.mul(feePercentage);
+            const expectedWorstTotalEthAmount = expectedWorstFillEthAmount.plus(expectedWorstFeeEthAmount);
             const expectedWorstEthPerAssetPrice = expectedWorstFillEthAmount.div(assetBuyAmount);
             expect(buyQuote.worstCaseQuoteInfo.feeEthAmount).to.bignumber.equal(expectedWorstFeeEthAmount);
             expect(buyQuote.worstCaseQuoteInfo.totalEthAmount).to.bignumber.equal(expectedWorstTotalEthAmount);