safeGetPartialAmount (#1035)

* Added Test "Should transfer correct amounts when left order is fully filled and values pass isRoundingErrorCeil but fail isRoundingErrorFloor"

* Added RoundingError exception to reference function for getPartialAmount

* Added RoundingError exception to reference function for getPartialAmount

* Added isRoundingErrorCeil to getPartialAmountCeil reference funtion

* Computed new values  for "Should give right maker a better buy price when correct price is not integral" that does not have a rounding error

* Almost all tests for match orders are passing after adding isRoundingErrorCeil check

* WIP commit: Added rounding error checks to getPartialAmount

* WIP commit: Added rounding error checks to getPartialAmount

* Use safe versions of getPartialAmount

* Update Exchange internals tests

* Run linter

* Found new values for "Should transfer correct amounts when right order fill amount deviates from amount derived by `Exchange.fillOrder`"

* Fixed merge conflicts

* Run all tests

* Cleaned up some comments on match Orders tests

* Fix tests for geth

1 files changed, 3 insertions, 13 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 be163ec97..64b1f7665 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/MixinExchangeCore.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinExchangeCore.sol
@@ -404,16 +404,6 @@ contract MixinExchangeCore is
             safeMul(order.makerAssetAmount, takerAssetFilledAmount),
             "INVALID_FILL_PRICE"
         );
-        
-        // Validate fill order rounding
-        require(
-            !isRoundingErrorFloor(
-                takerAssetFilledAmount,
-                order.takerAssetAmount,
-                order.makerAssetAmount
-            ),
-            "ROUNDING_ERROR"
-        );
     }
 
     /// @dev Validates context for cancelOrder. Succeeds or throws.
@@ -463,17 +453,17 @@ contract MixinExchangeCore is
     {
         // Compute proportional transfer amounts
         fillResults.takerAssetFilledAmount = takerAssetFilledAmount;
-        fillResults.makerAssetFilledAmount = getPartialAmountFloor(
+        fillResults.makerAssetFilledAmount = safeGetPartialAmountFloor(
             takerAssetFilledAmount,
             order.takerAssetAmount,
             order.makerAssetAmount
         );
-        fillResults.makerFeePaid = getPartialAmountFloor(
+        fillResults.makerFeePaid = safeGetPartialAmountFloor(
             takerAssetFilledAmount,
             order.takerAssetAmount,
             order.makerFee
         );
-        fillResults.takerFeePaid = getPartialAmountFloor(
+        fillResults.takerFeePaid = safeGetPartialAmountFloor(
             takerAssetFilledAmount,
             order.takerAssetAmount,
             order.takerFee