Add combinatorial tests for internal Exchange functions (#807)

* WIP add combinatorial tests for internal Exchange functions

* Change combinitorial testing strategy based on feedback

* Check value of filled[orderHash] in updateFilledState tests

* Add combinatorial tests for addFillResults

* Add combinatorial tests for getPartialAmount

* Implement generic `testWithReferenceFuncAsync`

* Implement generic `testCombinatoriallyWithReferenceFuncAsync`

* Add combinatorial tests for isRoundingError

* Add combinatorial tests for calculateFillResults

* Add support for Geth in internal contract tests

* Fix contract artifacts

* Change DECIMAL_PLACES to 78 and add a note.

* Document new functions in utils

* Optimize tests by only reseting state when needed

* Rename/move some files

* Print parameter names on failure in testWithReferenceFuncAsync

* Add to changelog for utils package

* Appease various linters

* Rename some more things related to FillOrderCombinatorialUtils

* Remove .only from test/exchange/internal.ts

* Remove old test for isRoundingError and getPartialAmount

* Appease linters again

* Remove old todos

* Fix typos, add comments, rename some things

* Re-add some LibMath tests

* Update contract internal tests to use new SafeMath revert reasons

* Apply PR feedback from Amir

* Apply PR feedback from Remco

* Re-add networks to ZRXToken artifact

* Remove duplicate Whitelist in compiler.json

2 files changed, 120 insertions, 1 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 354d0e9c3..ab5c6e507 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/MixinExchangeCore.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinExchangeCore.sol
@@ -207,7 +207,6 @@ contract MixinExchangeCore is
     /// @param order that was filled.
     /// @param takerAddress Address of taker who filled the order.
     /// @param orderTakerAssetFilledAmount Amount of order already filled.
-    /// @return fillResults Amounts filled and fees paid by maker and taker.
     function updateFilledState(
         Order memory order,
         address takerAddress,
diff --git a/packages/contracts/src/2.0.0/test/TestExchangeInternals/TestExchangeInternals.sol b/packages/contracts/src/2.0.0/test/TestExchangeInternals/TestExchangeInternals.sol
new file mode 100644
index 000000000..923bac97d
--- /dev/null
+++ b/packages/contracts/src/2.0.0/test/TestExchangeInternals/TestExchangeInternals.sol
@@ -0,0 +1,120 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../protocol/Exchange/Exchange.sol";
+
+
+contract TestExchangeInternals is
+    Exchange
+{
+    constructor ()
+        public
+        Exchange("")
+    {}
+
+    /// @dev Adds properties of both FillResults instances.
+    ///      Modifies the first FillResults instance specified.
+    ///      Note that this function has been modified from the original
+    //       internal version to return the FillResults.
+    /// @param totalFillResults Fill results instance that will be added onto.
+    /// @param singleFillResults Fill results instance that will be added to totalFillResults.
+    /// @return newTotalFillResults The result of adding singleFillResults to totalFilResults.
+    function publicAddFillResults(FillResults memory totalFillResults, FillResults memory singleFillResults)
+        public
+        pure
+        returns (FillResults memory)
+    {
+        addFillResults(totalFillResults, singleFillResults);
+        return totalFillResults;
+    }
+
+    /// @dev Calculates amounts filled and fees paid by maker and taker.
+    /// @param order to be filled.
+    /// @param takerAssetFilledAmount Amount of takerAsset that will be filled.
+    /// @return fillResults Amounts filled and fees paid by maker and taker.
+    function publicCalculateFillResults(
+        Order memory order,
+        uint256 takerAssetFilledAmount
+    )
+        public
+        pure
+        returns (FillResults memory fillResults)
+    {
+        return calculateFillResults(order, takerAssetFilledAmount);
+    }
+
+    /// @dev Calculates partial value given a numerator and denominator.
+    /// @param numerator Numerator.
+    /// @param denominator Denominator.
+    /// @param target Value to calculate partial of.
+    /// @return Partial value of target.
+    function publicGetPartialAmount(
+        uint256 numerator,
+        uint256 denominator,
+        uint256 target
+    )
+        public
+        pure
+        returns (uint256 partialAmount)
+    {
+        return getPartialAmount(numerator, denominator, target);
+    }
+
+    /// @dev Checks if rounding error > 0.1%.
+    /// @param numerator Numerator.
+    /// @param denominator Denominator.
+    /// @param target Value to multiply with numerator/denominator.
+    /// @return Rounding error is present.
+    function publicIsRoundingError(
+        uint256 numerator,
+        uint256 denominator,
+        uint256 target
+    )
+        public
+        pure
+        returns (bool isError)
+    {
+        return isRoundingError(numerator, denominator, target);
+    }
+ 
+    /// @dev Updates state with results of a fill order.
+    /// @param order that was filled.
+    /// @param takerAddress Address of taker who filled the order.
+    /// @param orderTakerAssetFilledAmount Amount of order already filled.
+    /// @return fillResults Amounts filled and fees paid by maker and taker.
+    function publicUpdateFilledState(
+        Order memory order,
+        address takerAddress,
+        bytes32 orderHash,
+        uint256 orderTakerAssetFilledAmount,
+        FillResults memory fillResults
+    )
+        public
+    {
+        updateFilledState(
+            order,
+            takerAddress,
+            orderHash,
+            orderTakerAssetFilledAmount,
+            fillResults
+        );
+    }
+}