Merge pull request #633 from 0xProject/feature/contracts/errors

Update error handling

30 files changed, 490 insertions, 737 deletions

diff --git a/packages/contracts/compiler.json b/packages/contracts/compiler.json
index ed59069fe..48ba4ffcd 100644
--- a/packages/contracts/compiler.json
+++ b/packages/contracts/compiler.json
@@ -4,7 +4,7 @@
     "compilerSettings": {
         "optimizer": {
             "enabled": true,
-            "runs": 0
+            "runs": 200
         },
         "outputSelection": {
             "*": {
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC20Proxy.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC20Proxy.sol
index 79824fbbb..2c321e134 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC20Proxy.sol
+++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC20Proxy.sol
@@ -20,9 +20,9 @@ pragma solidity ^0.4.24;
 pragma experimental ABIEncoderV2;
 
 import "../../utils/LibBytes/LibBytes.sol";
-import "../../tokens/ERC20Token/IERC20Token.sol";
 import "./MixinAssetProxy.sol";
 import "./MixinAuthorizable.sol";
+import "../../tokens/ERC20Token/IERC20Token.sol";
 
 contract ERC20Proxy is
     LibBytes,
@@ -33,11 +33,6 @@ contract ERC20Proxy is
     // Id of this proxy.
     uint8 constant PROXY_ID = 1;
 
-    // Revert reasons
-    string constant INVALID_METADATA_LENGTH = "Metadata must have a length of 21.";
-    string constant TRANSFER_FAILED = "Transfer failed.";
-    string constant PROXY_ID_MISMATCH = "Proxy id in metadata does not match this proxy id.";
-
     /// @dev Internal version of `transferFrom`.
     /// @param assetMetadata Encoded byte array.
     /// @param from Address to transfer asset from.
@@ -56,12 +51,12 @@ contract ERC20Proxy is
 
         require(
             length == 21,
-            INVALID_METADATA_LENGTH
+            LENGTH_21_REQUIRED
         );
-
+        // TODO: Is this too inflexible in the future?
         require(
             uint8(assetMetadata[length - 1]) == PROXY_ID,
-            PROXY_ID_MISMATCH
+            ASSET_PROXY_ID_MISMATCH
         );
 
         // Decode metadata.
@@ -70,7 +65,7 @@ contract ERC20Proxy is
         // Transfer tokens.
         bool success = IERC20Token(token).transferFrom(from, to, amount);
         require(
-            success == true,
+            success,
             TRANSFER_FAILED
         );
     }
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC721Proxy.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC721Proxy.sol
index ace3570bc..07e01c774 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC721Proxy.sol
+++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC721Proxy.sol
@@ -20,9 +20,9 @@ pragma solidity ^0.4.24;
 pragma experimental ABIEncoderV2;
 
 import "../../utils/LibBytes/LibBytes.sol";
-import "../../tokens/ERC721Token/ERC721Token.sol";
 import "./MixinAssetProxy.sol";
 import "./MixinAuthorizable.sol";
+import "../../tokens/ERC721Token/ERC721Token.sol";
 
 contract ERC721Proxy is
     LibBytes,
@@ -33,11 +33,6 @@ contract ERC721Proxy is
     // Id of this proxy.
     uint8 constant PROXY_ID = 2;
 
-    // Revert reasons
-    string constant INVALID_TRANSFER_AMOUNT = "Transfer amount must equal 1.";
-    string constant INVALID_METADATA_LENGTH = "Metadata must have a length of 53.";
-    string constant PROXY_ID_MISMATCH = "Proxy id in metadata does not match this proxy id.";
-
     /// @dev Internal version of `transferFrom`.
     /// @param assetMetadata Encoded byte array.
     /// @param from Address to transfer asset from.
@@ -56,18 +51,19 @@ contract ERC721Proxy is
 
         require(
             length == 53,
-            INVALID_METADATA_LENGTH
+            LENGTH_53_REQUIRED
         );
 
+        // TODO: Is this too inflexible in the future?
         require(
             uint8(assetMetadata[length - 1]) == PROXY_ID,
-            PROXY_ID_MISMATCH
+            ASSET_PROXY_ID_MISMATCH
         );
 
         // There exists only 1 of each token.
         require(
             amount == 1,
-            INVALID_TRANSFER_AMOUNT
+            INVALID_AMOUNT
         );
 
         // Decode metadata
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinAssetProxy.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinAssetProxy.sol
index 4bd533148..5fa33cbef 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinAssetProxy.sol
+++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinAssetProxy.sol
@@ -19,10 +19,10 @@
 pragma solidity ^0.4.24;
 pragma experimental ABIEncoderV2;
 
-import "./mixins/MAssetProxy.sol";
 import "./mixins/MAuthorizable.sol";
+import "./mixins/MAssetProxy.sol";
 
-contract MixinAssetProxy is 
+contract MixinAssetProxy is
     MAuthorizable,
     MAssetProxy
 {
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinAuthorizable.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinAuthorizable.sol
index 4aaeb66d1..8cb4254c5 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinAuthorizable.sol
+++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinAuthorizable.sol
@@ -19,21 +19,16 @@
 pragma solidity ^0.4.24;
 pragma experimental ABIEncoderV2;
 
-import "./mixins/MAuthorizable.sol";
+import "./libs/LibAssetProxyErrors.sol";
 import "../../utils/Ownable/Ownable.sol";
+import "./mixins/MAuthorizable.sol";
 
 contract MixinAuthorizable is
+    LibAssetProxyErrors,
     Ownable,
     MAuthorizable
 {
 
-    // Revert reasons
-    string constant SENDER_NOT_AUTHORIZED = "Sender not authorized to call this method.";
-    string constant TARGET_NOT_AUTHORIZED = "Target address must be authorized.";
-    string constant TARGET_ALREADY_AUTHORIZED = "Target must not already be authorized.";
-    string constant INDEX_OUT_OF_BOUNDS = "Specified array index is out of bounds.";
-    string constant INDEX_ADDRESS_MISMATCH = "Address found at index does not match target address.";
-
     /// @dev Only authorized addresses can invoke functions with this modifier.
     modifier onlyAuthorized {
         require(
@@ -99,7 +94,7 @@ contract MixinAuthorizable is
         );
         require(
             authorities[index] == target,
-            INDEX_ADDRESS_MISMATCH
+            AUTHORIZED_ADDRESS_MISMATCH
         );
 
         delete authorized[target];
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/libs/LibAssetProxyErrors.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/libs/LibAssetProxyErrors.sol
new file mode 100644
index 000000000..e0c7fc796
--- /dev/null
+++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/libs/LibAssetProxyErrors.sol
@@ -0,0 +1,37 @@
+/*
+
+  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;
+
+contract LibAssetProxyErrors {
+    /// Authorizable errors ///
+    string constant SENDER_NOT_AUTHORIZED = "SENDER_NOT_AUTHORIZED";              // Sender not authorized to call this method.
+    string constant TARGET_NOT_AUTHORIZED = "TARGET_NOT_AUTHORIZED";              // Target address not authorized to call this method.
+    string constant TARGET_ALREADY_AUTHORIZED = "TARGET_ALREADY_AUTHORIZED";      // Target address must not already be authorized.
+    string constant INDEX_OUT_OF_BOUNDS = "INDEX_OUT_OF_BOUNDS";                  // Specified array index is out of bounds.
+    string constant AUTHORIZED_ADDRESS_MISMATCH = "AUTHORIZED_ADDRESS_MISMATCH";  // Address at index does not match given target address.
+
+    /// AssetProxy errors ///
+    string constant ASSET_PROXY_ID_MISMATCH = "ASSET_PROXY_ID_MISMATCH";          // Proxy id in metadata does not match this proxy id.
+    string constant INVALID_AMOUNT = "INVALID_AMOUNT";                            // Transfer amount must equal 1.
+    string constant TRANSFER_FAILED = "TRANSFER_FAILED";                          // Transfer failed. 
+
+    /// Length validation errors ///
+    string constant LENGTH_21_REQUIRED = "LENGTH_21_REQUIRED";                    // Byte array must have a length of 21.
+    string constant LENGTH_53_REQUIRED = "LENGTH_53_REQUIRED";                    // Byte array must have a length of 53.
+}
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinAssetProxyDispatcher.sol b/packages/contracts/src/contracts/current/protocol/Exchange/MixinAssetProxyDispatcher.sol
index d996f933c..8f9342739 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinAssetProxyDispatcher.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/MixinAssetProxyDispatcher.sol
@@ -19,13 +19,13 @@
 pragma solidity ^0.4.24;
 
 import "../../utils/Ownable/Ownable.sol";
-import "../AssetProxy/interfaces/IAssetProxy.sol";
 import "./libs/LibExchangeErrors.sol";
 import "./mixins/MAssetProxyDispatcher.sol";
+import "../AssetProxy/interfaces/IAssetProxy.sol";
 
 contract MixinAssetProxyDispatcher is
-    LibExchangeErrors,
     Ownable,
+    LibExchangeErrors,
     MAssetProxyDispatcher
 {
     // Mapping from Asset Proxy Id's to their respective Asset Proxy
@@ -45,9 +45,10 @@ contract MixinAssetProxyDispatcher is
         onlyOwner
     {
         // Ensure the existing asset proxy is not unintentionally overwritten
+        address currentAssetProxy = address(assetProxies[assetProxyId]);
         require(
-            oldAssetProxy == address(assetProxies[assetProxyId]),
-            OLD_ASSET_PROXY_MISMATCH
+            oldAssetProxy == currentAssetProxy,
+            ASSET_PROXY_MISMATCH
         );
 
         IAssetProxy assetProxy = IAssetProxy(newAssetProxy);
@@ -57,7 +58,7 @@ contract MixinAssetProxyDispatcher is
             uint8 newAssetProxyId = assetProxy.getProxyId();
             require(
                 newAssetProxyId == assetProxyId,
-                NEW_ASSET_PROXY_MISMATCH
+                ASSET_PROXY_ID_MISMATCH
             );
         }
 
@@ -98,7 +99,7 @@ contract MixinAssetProxyDispatcher is
             uint256 length = assetMetadata.length;
             require(
                 length > 0,
-                GT_ZERO_LENGTH_REQUIRED
+                LENGTH_GREATER_THAN_0_REQUIRED
             );
             uint8 assetProxyId = uint8(assetMetadata[length - 1]);
             IAssetProxy assetProxy = assetProxies[assetProxyId];
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinExchangeCore.sol b/packages/contracts/src/contracts/current/protocol/Exchange/MixinExchangeCore.sol
index 1c2420374..42128c92a 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinExchangeCore.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/MixinExchangeCore.sol
@@ -22,7 +22,6 @@ pragma experimental ABIEncoderV2;
 import "./libs/LibFillResults.sol";
 import "./libs/LibOrder.sol";
 import "./libs/LibMath.sol";
-import "./libs/LibStatus.sol";
 import "./libs/LibExchangeErrors.sol";
 import "./mixins/MExchangeCore.sol";
 import "./mixins/MSettlement.sol";
@@ -30,9 +29,7 @@ import "./mixins/MSignatureValidator.sol";
 import "./mixins/MTransactions.sol";
 
 contract MixinExchangeCore is
-    SafeMath,
     LibMath,
-    LibStatus,
     LibOrder,
     LibFillResults,
     LibExchangeErrors,
@@ -58,13 +55,21 @@ contract MixinExchangeCore is
     function cancelOrdersUpTo(uint256 salt)
         external
     {
-        uint256 newMakerEpoch = salt + 1;  // makerEpoch is initialized to 0, so to cancelUpTo we need salt + 1
+        address makerAddress = getCurrentContextAddress();
+
+        // makerEpoch is initialized to 0, so to cancelUpTo we need salt + 1
+        uint256 newMakerEpoch = salt + 1;  
+        uint256 oldMakerEpoch = makerEpoch[makerAddress];
+
+        // Ensure makerEpoch is monotonically increasing
         require(
-            newMakerEpoch > makerEpoch[msg.sender],  // epoch must be monotonically increasing
+            newMakerEpoch > oldMakerEpoch, 
             INVALID_NEW_MAKER_EPOCH
         );
-        makerEpoch[msg.sender] = newMakerEpoch;
-        emit CancelUpTo(msg.sender, newMakerEpoch);
+
+        // Update makerEpoch
+        makerEpoch[makerAddress] = newMakerEpoch;
+        emit CancelUpTo(makerAddress, newMakerEpoch);
     }
 
     /// @dev Fills the input order.
@@ -86,29 +91,22 @@ contract MixinExchangeCore is
         // Fetch taker address
         address takerAddress = getCurrentContextAddress();
 
-        // Either our context is valid or we revert
+        // Get amount of takerAsset to fill
+        uint256 remainingTakerAssetAmount = safeSub(order.takerAssetAmount, orderInfo.orderTakerAssetFilledAmount);
+        uint256 takerAssetFilledAmount = min256(takerAssetFillAmount, remainingTakerAssetAmount);
+
+        // Validate context
         assertValidFill(
             order,
-            orderInfo.orderStatus,
-            orderInfo.orderHash,
+            orderInfo,
             takerAddress,
-            orderInfo.orderTakerAssetFilledAmount,
             takerAssetFillAmount,
+            takerAssetFilledAmount,
             signature
         );
 
         // Compute proportional fill amounts
-        uint8 status;
-        (status, fillResults) = calculateFillResults(
-            order,
-            orderInfo.orderStatus,
-            orderInfo.orderTakerAssetFilledAmount,
-            takerAssetFillAmount
-        );
-        if (status != uint8(Status.SUCCESS)) {
-            emit ExchangeStatus(uint8(status), orderInfo.orderHash);
-            return getNullFillResults();
-        }
+        fillResults = calculateFillResults(order, takerAssetFilledAmount);
 
         // Settle order
         settleOrder(order, takerAddress, fillResults);
@@ -126,32 +124,28 @@ contract MixinExchangeCore is
 
     /// @dev After calling, the order can not be filled anymore.
     ///      Throws if order is invalid or sender does not have permission to cancel.
-    /// @param order Order to cancel. Order must be Status.FILLABLE.
-    /// @return True if the order state changed to cancelled.
-    ///         False if the order was valid, but in an
-    ///               unfillable state (see LibStatus.STATUS for order states)
+    /// @param order Order to cancel. Order must be OrderStatus.FILLABLE.
     function cancelOrder(Order memory order)
         public
-        returns (bool)
     {
         // Fetch current order status
         OrderInfo memory orderInfo = getOrderInfo(order);
 
         // Validate context
-        assertValidCancel(order, orderInfo.orderStatus, orderInfo.orderHash);
+        assertValidCancel(order, orderInfo);
 
         // Perform cancel
-        return updateCancelledState(order, orderInfo.orderStatus, orderInfo.orderHash);
+        updateCancelledState(order, orderInfo.orderHash);
     }
 
     /// @dev Gets information about an order: status, hash, and amount filled.
     /// @param order Order to gather information on.
     /// @return OrderInfo Information about the order and its state.
-    ///                   See LibOrder.OrderInfo for a complete description.
+    ///         See LibOrder.OrderInfo for a complete description.
     function getOrderInfo(Order memory order)
         public
         view
-        returns (LibOrder.OrderInfo memory orderInfo)
+        returns (OrderInfo memory orderInfo)
     {
         // Compute the order hash
         orderInfo.orderHash = getOrderHash(order);
@@ -161,7 +155,7 @@ contract MixinExchangeCore is
         // edge cases in the supporting infrastructure because they have
         // an 'infinite' price when computed by a simple division.
         if (order.makerAssetAmount == 0) {
-            orderInfo.orderStatus = uint8(Status.ORDER_INVALID_MAKER_ASSET_AMOUNT);
+            orderInfo.orderStatus = uint8(OrderStatus.INVALID_MAKER_ASSET_AMOUNT);
             return orderInfo;
         }
 
@@ -170,148 +164,124 @@ contract MixinExchangeCore is
         // Instead of distinguishing between unfilled and filled zero taker
         // amount orders, we choose not to support them.
         if (order.takerAssetAmount == 0) {
-            orderInfo.orderStatus = uint8(Status.ORDER_INVALID_TAKER_ASSET_AMOUNT);
+            orderInfo.orderStatus = uint8(OrderStatus.INVALID_TAKER_ASSET_AMOUNT);
             return orderInfo;
         }
 
         // Validate order expiration
         if (block.timestamp >= order.expirationTimeSeconds) {
-            orderInfo.orderStatus = uint8(Status.ORDER_EXPIRED);
+            orderInfo.orderStatus = uint8(OrderStatus.EXPIRED);
             return orderInfo;
         }
 
         // Check if order has been cancelled
         if (cancelled[orderInfo.orderHash]) {
-            orderInfo.orderStatus = uint8(Status.ORDER_CANCELLED);
+            orderInfo.orderStatus = uint8(OrderStatus.CANCELLED);
             return orderInfo;
         }
         if (makerEpoch[order.makerAddress] > order.salt) {
-            orderInfo.orderStatus = uint8(Status.ORDER_CANCELLED);
+            orderInfo.orderStatus = uint8(OrderStatus.CANCELLED);
             return orderInfo;
         }
 
         // Fetch filled amount and validate order availability
         orderInfo.orderTakerAssetFilledAmount = filled[orderInfo.orderHash];
         if (orderInfo.orderTakerAssetFilledAmount >= order.takerAssetAmount) {
-            orderInfo.orderStatus = uint8(Status.ORDER_FULLY_FILLED);
+            orderInfo.orderStatus = uint8(OrderStatus.FULLY_FILLED);
             return orderInfo;
         }
 
         // All other statuses are ruled out: order is Fillable
-        orderInfo.orderStatus = uint8(Status.ORDER_FILLABLE);
+        orderInfo.orderStatus = uint8(OrderStatus.FILLABLE);
         return orderInfo;
     }
 
-    /// @dev Calculates amounts filled and fees paid by maker and taker.
-    /// @param order to be filled.
-    /// @param orderStatus Status of order to be filled.
+    /// @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.
-    /// @param takerAssetFillAmount Desired amount of order to fill by taker.
-    /// @return status Return status of calculating fill amounts. Returns Status.SUCCESS on success.
     /// @return fillResults Amounts filled and fees paid by maker and taker.
-    function calculateFillResults(
+    function updateFilledState(
         Order memory order,
-        uint8 orderStatus,
+        address takerAddress,
+        bytes32 orderHash,
         uint256 orderTakerAssetFilledAmount,
-        uint256 takerAssetFillAmount
+        FillResults memory fillResults
     )
-        public
-        pure
-        returns (
-            uint8 status,
-            FillResults memory fillResults
-        )
+        internal
     {
-        // Fill amount must be greater than 0
-        if (takerAssetFillAmount == 0) {
-            status = uint8(Status.TAKER_ASSET_FILL_AMOUNT_TOO_LOW);
-            return (status, fillResults);
-        }
-
-        // Ensure the order is fillable
-        if (orderStatus != uint8(Status.ORDER_FILLABLE)) {
-            status = orderStatus;
-            return (status, fillResults);
-        }
-
-        // Compute takerAssetFilledAmount
-        uint256 remainingTakerAssetAmount = safeSub(order.takerAssetAmount, orderTakerAssetFilledAmount);
-        uint256 takerAssetFilledAmount = min256(takerAssetFillAmount, remainingTakerAssetAmount);
-
-        // Validate fill order rounding
-        if (isRoundingError(
-            takerAssetFilledAmount,
-            order.takerAssetAmount,
-            order.makerAssetAmount))
-        {
-            status = uint8(Status.ROUNDING_ERROR_TOO_LARGE);
-            return (status, fillResults);
-        }
+        // Update state
+        filled[orderHash] = safeAdd(orderTakerAssetFilledAmount, fillResults.takerAssetFilledAmount);
 
-        // Compute proportional transfer amounts
-        // TODO: All three are multiplied by the same fraction. This can
-        // potentially be optimized.
-        fillResults.takerAssetFilledAmount = takerAssetFilledAmount;
-        fillResults.makerAssetFilledAmount = getPartialAmount(
-            fillResults.takerAssetFilledAmount,
-            order.takerAssetAmount,
-            order.makerAssetAmount
-        );
-        fillResults.makerFeePaid = getPartialAmount(
-            fillResults.takerAssetFilledAmount,
-            order.takerAssetAmount,
-            order.makerFee
-        );
-        fillResults.takerFeePaid = getPartialAmount(
+        // Log order
+        emit Fill(
+            order.makerAddress,
+            takerAddress,
+            order.feeRecipientAddress,
+            fillResults.makerAssetFilledAmount,
             fillResults.takerAssetFilledAmount,
-            order.takerAssetAmount,
-            order.takerFee
+            fillResults.makerFeePaid,
+            fillResults.takerFeePaid,
+            orderHash,
+            order.makerAssetData,
+            order.takerAssetData
         );
+    }
+
+    /// @dev Updates state with results of cancelling an order.
+    ///      State is only updated if the order is currently fillable.
+    ///      Otherwise, updating state would have no effect.
+    /// @param order that was cancelled.
+    /// @param orderHash Hash of order that was cancelled.
+    function updateCancelledState(
+        Order memory order,
+        bytes32 orderHash
+    )
+        internal
+    {
+        // Perform cancel
+        cancelled[orderHash] = true;
 
-        status = uint8(Status.SUCCESS);
-        return (status, fillResults);
+        // Log cancel
+        emit Cancel(
+            order.makerAddress,
+            order.feeRecipientAddress,
+            orderHash,
+            order.makerAssetData,
+            order.takerAssetData
+        );
     }
 
     /// @dev Validates context for fillOrder. Succeeds or throws.
     /// @param order to be filled.
-    /// @param orderStatus Status of order to be filled.
-    /// @param orderHash Hash of order to be filled.
+    /// @param orderInfo OrderStatus, orderHash, and amount already filled of order.
     /// @param takerAddress Address of order taker.
-    /// @param orderTakerAssetFilledAmount Amount of order already filled.
     /// @param takerAssetFillAmount Desired amount of order to fill by taker.
+    /// @param takerAssetFilledAmount Amount of takerAsset that will be filled.
     /// @param signature Proof that the orders was created by its maker.
     function assertValidFill(
         Order memory order,
-        uint8 orderStatus,
-        bytes32 orderHash,
+        OrderInfo memory orderInfo,
         address takerAddress,
-        uint256 orderTakerAssetFilledAmount,
         uint256 takerAssetFillAmount,
+        uint256 takerAssetFilledAmount,
         bytes memory signature
     )
         internal
+        view
     {
-        // Ensure order is valid
-        // An order can only be filled if its status is FILLABLE;
-        // however, only invalid statuses result in a throw.
-        // See LibStatus for a complete description of order statuses.
+        // An order can only be filled if its status is FILLABLE.
         require(
-            orderStatus != uint8(Status.ORDER_INVALID_MAKER_ASSET_AMOUNT),
-            INVALID_ORDER_MAKER_ASSET_AMOUNT
+            orderInfo.orderStatus == uint8(OrderStatus.FILLABLE),
+            ORDER_UNFILLABLE
         );
+
+        // Revert if fill amount is invalid
         require(
-            orderStatus != uint8(Status.ORDER_INVALID_TAKER_ASSET_AMOUNT),
-            INVALID_ORDER_TAKER_ASSET_AMOUNT
+            takerAssetFillAmount != 0,
+            INVALID_TAKER_AMOUNT
         );
 
-        // Validate Maker signature (check only if first time seen)
-        if (orderTakerAssetFilledAmount == 0) {
-            require(
-                isValidSignature(orderHash, order.makerAddress, signature),
-                SIGNATURE_VALIDATION_FAILED
-            );
-        }
-
         // Validate sender is allowed to fill this order
         if (order.senderAddress != address(0)) {
             require(
@@ -324,76 +294,44 @@ contract MixinExchangeCore is
         if (order.takerAddress != address(0)) {
             require(
                 order.takerAddress == takerAddress,
-                INVALID_CONTEXT
+                INVALID_TAKER
             );
         }
-        require(
-            takerAssetFillAmount > 0,
-            GT_ZERO_AMOUNT_REQUIRED
-        );
-    }
 
-    /// @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 updateFilledState(
-        Order memory order,
-        address takerAddress,
-        bytes32 orderHash,
-        uint256 orderTakerAssetFilledAmount,
-        FillResults memory fillResults
-    )
-        internal
-    {
-        // Update state
-        filled[orderHash] = safeAdd(orderTakerAssetFilledAmount, fillResults.takerAssetFilledAmount);
+        // Validate Maker signature (check only if first time seen)
+        if (orderInfo.orderTakerAssetFilledAmount == 0) {
+            require(
+                isValidSignature(orderInfo.orderHash, order.makerAddress, signature),
+                INVALID_ORDER_SIGNATURE
+            );
+        }
 
-        // Log order
-        emit Fill(
-            order.makerAddress,
-            takerAddress,
-            order.feeRecipientAddress,
-            fillResults.makerAssetFilledAmount,
-            fillResults.takerAssetFilledAmount,
-            fillResults.makerFeePaid,
-            fillResults.takerFeePaid,
-            orderHash,
-            order.makerAssetData,
-            order.takerAssetData
+        // Validate fill order rounding
+        require(
+            !isRoundingError(
+                takerAssetFilledAmount,
+                order.takerAssetAmount,
+                order.makerAssetAmount
+            ),
+            ROUNDING_ERROR
         );
     }
 
     /// @dev Validates context for cancelOrder. Succeeds or throws.
-    /// @param order that was cancelled.
-    /// @param orderStatus Status of order that was cancelled.
-    /// @param orderHash Hash of order that was cancelled.
+    /// @param order to be cancelled.
+    /// @param orderInfo OrderStatus, orderHash, and amount already filled of order.
     function assertValidCancel(
         Order memory order,
-        uint8 orderStatus,
-        bytes32 orderHash
+        OrderInfo memory orderInfo
     )
         internal
+        view
     {
         // Ensure order is valid
-        // An order can only be cancelled if its status is FILLABLE;
-        // however, only invalid statuses result in a throw.
-        // See LibStatus for a complete description of order statuses.
-        require(
-            orderStatus != uint8(Status.ORDER_INVALID_MAKER_ASSET_AMOUNT),
-            INVALID_ORDER_MAKER_ASSET_AMOUNT
-        );
+        // An order can only be cancelled if its status is FILLABLE.
         require(
-            orderStatus != uint8(Status.ORDER_INVALID_TAKER_ASSET_AMOUNT),
-            INVALID_ORDER_TAKER_ASSET_AMOUNT
-        );
-
-        // Validate transaction signed by maker
-        address makerAddress = getCurrentContextAddress();
-        require(
-            order.makerAddress == makerAddress,
-            INVALID_CONTEXT
+            orderInfo.orderStatus == uint8(OrderStatus.FILLABLE),
+            ORDER_UNFILLABLE
         );
 
         // Validate sender is allowed to cancel this order
@@ -403,44 +341,47 @@ contract MixinExchangeCore is
                 INVALID_SENDER
             );
         }
+
+        // Validate transaction signed by maker
+        address makerAddress = getCurrentContextAddress();
+        require(
+            order.makerAddress == makerAddress,
+            INVALID_MAKER
+        );
     }
 
-    /// @dev Updates state with results of cancelling an order.
-    ///      State is only updated if the order is currently fillable.
-    ///      Otherwise, updating state would have no effect.
-    /// @param order that was cancelled.
-    /// @param orderStatus Status of order that was cancelled.
-    /// @param orderHash Hash of order that was cancelled.
-    /// @return stateUpdated Returns true only if state was updated.
-    function updateCancelledState(
+    /// @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 calculateFillResults(
         Order memory order,
-        uint8 orderStatus,
-        bytes32 orderHash
+        uint256 takerAssetFilledAmount
     )
         internal
-        returns (bool stateUpdated)
+        pure
+        returns (FillResults memory fillResults)
     {
-        // Ensure order is fillable (otherwise cancelling does nothing)
-        // See LibStatus for a complete description of order statuses.
-        if (orderStatus != uint8(Status.ORDER_FILLABLE)) {
-            emit ExchangeStatus(uint8(orderStatus), orderHash);
-            stateUpdated = false;
-            return stateUpdated;
-        }
-
-        // Perform cancel
-        cancelled[orderHash] = true;
-        stateUpdated = true;
-
-        // Log cancel
-        emit Cancel(
-            order.makerAddress,
-            order.feeRecipientAddress,
-            orderHash,
-            order.makerAssetData,
-            order.takerAssetData
+        // Compute proportional transfer amounts
+        // TODO: All three are multiplied by the same fraction. This can
+        // potentially be optimized.
+        fillResults.takerAssetFilledAmount = takerAssetFilledAmount;
+        fillResults.makerAssetFilledAmount = getPartialAmount(
+            fillResults.takerAssetFilledAmount,
+            order.takerAssetAmount,
+            order.makerAssetAmount
+        );
+        fillResults.makerFeePaid = getPartialAmount(
+            fillResults.takerAssetFilledAmount,
+            order.takerAssetAmount,
+            order.makerFee
+        );
+        fillResults.takerFeePaid = getPartialAmount(
+            fillResults.takerAssetFilledAmount,
+            order.takerAssetAmount,
+            order.takerFee
         );
 
-        return stateUpdated;
+        return fillResults;
     }
 }
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinMatchOrders.sol b/packages/contracts/src/contracts/current/protocol/Exchange/MixinMatchOrders.sol
index 9d8b521c0..ed76287e0 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinMatchOrders.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/MixinMatchOrders.sol
@@ -14,24 +14,19 @@
 pragma solidity ^0.4.24;
 pragma experimental ABIEncoderV2;
 
+import "../../utils/LibBytes/LibBytes.sol";
+import "./libs/LibMath.sol";
+import "./libs/LibOrder.sol";
+import "./libs/LibFillResults.sol";
+import "./libs/LibExchangeErrors.sol";
 import "./mixins/MExchangeCore.sol";
 import "./mixins/MMatchOrders.sol";
 import "./mixins/MSettlement.sol";
 import "./mixins/MTransactions.sol";
-import "../../utils/SafeMath/SafeMath.sol";
-import "./libs/LibMath.sol";
-import "./libs/LibOrder.sol";
-import "./libs/LibStatus.sol";
-import "../../utils/LibBytes/LibBytes.sol";
-import "./libs/LibExchangeErrors.sol";
 
 contract MixinMatchOrders is
-    SafeMath,
     LibBytes,
     LibMath,
-    LibStatus,
-    LibOrder,
-    LibFillResults,
     LibExchangeErrors,
     MExchangeCore,
     MMatchOrders,
@@ -50,17 +45,22 @@ contract MixinMatchOrders is
     /// @return matchedFillResults Amounts filled and fees paid by maker and taker of matched orders.
     /// TODO: Make this function external once supported by Solidity (See Solidity Issues #3199, #1603)
     function matchOrders(
-        Order memory leftOrder,
-        Order memory rightOrder,
+        LibOrder.Order memory leftOrder,
+        LibOrder.Order memory rightOrder,
         bytes memory leftSignature,
         bytes memory rightSignature
     )
         public
-        returns (MatchedFillResults memory matchedFillResults)
+        returns (LibFillResults.MatchedFillResults memory matchedFillResults)
     {
+        // We assume that rightOrder.takerAssetData == leftOrder.makerAssetData and rightOrder.makerAssetData == leftOrder.takerAssetData.
+        // If this assumption isn't true, the match will fail at signature validation.
+        rightOrder.makerAssetData = leftOrder.takerAssetData;
+        rightOrder.takerAssetData = leftOrder.makerAssetData;
+
         // Get left & right order info
-        OrderInfo memory leftOrderInfo = getOrderInfo(leftOrder);
-        OrderInfo memory rightOrderInfo = getOrderInfo(rightOrder);
+        LibOrder.OrderInfo memory leftOrderInfo = getOrderInfo(leftOrder);
+        LibOrder.OrderInfo memory rightOrderInfo = getOrderInfo(rightOrder);
 
         // Fetch taker address
         address takerAddress = getCurrentContextAddress();
@@ -72,8 +72,6 @@ contract MixinMatchOrders is
         matchedFillResults = calculateMatchedFillResults(
             leftOrder,
             rightOrder,
-            leftOrderInfo.orderStatus,
-            rightOrderInfo.orderStatus,
             leftOrderInfo.orderTakerAssetFilledAmount,
             rightOrderInfo.orderTakerAssetFilledAmount
         );
@@ -81,19 +79,17 @@ contract MixinMatchOrders is
         // Validate fill contexts
         assertValidFill(
             leftOrder,
-            leftOrderInfo.orderStatus,
-            leftOrderInfo.orderHash,
+            leftOrderInfo,
             takerAddress,
-            leftOrderInfo.orderTakerAssetFilledAmount,
+            matchedFillResults.left.takerAssetFilledAmount,
             matchedFillResults.left.takerAssetFilledAmount,
             leftSignature
         );
         assertValidFill(
             rightOrder,
-            rightOrderInfo.orderStatus,
-            rightOrderInfo.orderHash,
+            rightOrderInfo,
             takerAddress,
-            rightOrderInfo.orderTakerAssetFilledAmount,
+            matchedFillResults.right.takerAssetFilledAmount,
             matchedFillResults.right.takerAssetFilledAmount,
             rightSignature
         );
@@ -129,25 +125,12 @@ contract MixinMatchOrders is
     /// @param leftOrder First order to match.
     /// @param rightOrder Second order to match.
     function assertValidMatch(
-        Order memory leftOrder,
-        Order memory rightOrder
+        LibOrder.Order memory leftOrder,
+        LibOrder.Order memory rightOrder
     )
         internal
+        pure
     {
-        // The leftOrder maker asset must be the same as the rightOrder taker asset.
-        // TODO: Can we safely assume equality and expect a later failure otherwise?
-        require(
-            areBytesEqual(leftOrder.makerAssetData, rightOrder.takerAssetData),
-            ASSET_MISMATCH_MAKER_TAKER
-        );
-
-        // The leftOrder taker asset must be the same as the rightOrder maker asset.
-        // TODO: Can we safely assume equality and expect a later failure otherwise?
-        require(
-            areBytesEqual(leftOrder.takerAssetData, rightOrder.makerAssetData),
-            ASSET_MISMATCH_TAKER_MAKER
-        );
-
         // Make sure there is a profitable spread.
         // There is a profitable spread iff the cost per unit bought (OrderA.MakerAmount/OrderA.TakerAmount) for each order is greater
         // than the profit per unit sold of the matched order (OrderB.TakerAmount/OrderB.MakerAmount).
@@ -159,39 +142,7 @@ contract MixinMatchOrders is
         require(
             safeMul(leftOrder.makerAssetAmount, rightOrder.makerAssetAmount) >=
             safeMul(leftOrder.takerAssetAmount, rightOrder.takerAssetAmount),
-            NEGATIVE_SPREAD
-        );
-    }
-
-    /// @dev Validates matched fill results. Succeeds or throws.
-    /// @param matchedFillResults Amounts to fill and fees to pay by maker and taker of matched orders.
-    function assertValidMatchResults(MatchedFillResults memory matchedFillResults)
-        internal
-    {
-        // If the amount transferred from the left order is different than what is transferred, it is a rounding error amount.
-        // Ensure this difference is negligible by dividing the values with each other. The result should equal to ~1.
-        uint256 amountSpentByLeft = safeAdd(
-            matchedFillResults.right.takerAssetFilledAmount,
-            matchedFillResults.takerFillAmount
-        );
-        require(
-            !isRoundingError(
-                matchedFillResults.left.makerAssetFilledAmount,
-                amountSpentByLeft,
-                1
-            ),
-            ROUNDING_ERROR_TRANSFER_AMOUNTS
-        );
-
-        // If the amount transferred from the right order is different than what is transferred, it is a rounding error amount.
-        // Ensure this difference is negligible by dividing the values with each other. The result should equal to ~1.
-        require(
-            !isRoundingError(
-                matchedFillResults.right.makerAssetFilledAmount,
-                matchedFillResults.left.takerAssetFilledAmount,
-                1
-            ),
-            ROUNDING_ERROR_TRANSFER_AMOUNTS
+            NEGATIVE_SPREAD_REQUIRED
         );
     }
 
@@ -201,21 +152,18 @@ contract MixinMatchOrders is
     ///      The profit made by the leftOrder order goes to the taker (who matched the two orders).
     /// @param leftOrder First order to match.
     /// @param rightOrder Second order to match.
-    /// @param leftOrderStatus Order status of left order.
-    /// @param rightOrderStatus Order status of right order.
-    /// @param leftOrderFilledAmount Amount of left order already filled.
-    /// @param rightOrderFilledAmount Amount of right order already filled.
+    /// @param leftOrderTakerAssetFilledAmount Amount of left order already filled.
+    /// @param rightOrderTakerAssetFilledAmount Amount of right order already filled.
     /// @param matchedFillResults Amounts to fill and fees to pay by maker and taker of matched orders.
     function calculateMatchedFillResults(
-        Order memory leftOrder,
-        Order memory rightOrder,
-        uint8 leftOrderStatus,
-        uint8 rightOrderStatus,
-        uint256 leftOrderFilledAmount,
-        uint256 rightOrderFilledAmount
+        LibOrder.Order memory leftOrder,
+        LibOrder.Order memory rightOrder,
+        uint256 leftOrderTakerAssetFilledAmount,
+        uint256 rightOrderTakerAssetFilledAmount
     )
         internal
-        returns (MatchedFillResults memory matchedFillResults)
+        pure
+        returns (LibFillResults.MatchedFillResults memory matchedFillResults)
     {
         // We settle orders at the exchange rate of the right order.
         // The amount saved by the left maker goes to the taker.
@@ -226,71 +174,55 @@ contract MixinMatchOrders is
         //          <leftTakerAssetAmountRemaining> <= <rightTakerAssetAmountRemaining> * <rightMakerToTakerRatio>
         //          <leftTakerAssetAmountRemaining> <= <rightTakerAssetAmountRemaining> * <rightOrder.makerAssetAmount> / <rightOrder.takerAssetAmount>
         //          <leftTakerAssetAmountRemaining> * <rightOrder.takerAssetAmount> <= <rightTakerAssetAmountRemaining> * <rightOrder.makerAssetAmount>
-        uint256 rightTakerAssetAmountRemaining = safeSub(rightOrder.takerAssetAmount, rightOrderFilledAmount);
-        uint256 leftTakerAssetAmountRemaining = safeSub(leftOrder.takerAssetAmount, leftOrderFilledAmount);
-        uint256 leftOrderAmountToFill;
-        uint256 rightOrderAmountToFill;
+        uint256 leftTakerAssetAmountRemaining = safeSub(leftOrder.takerAssetAmount, leftOrderTakerAssetFilledAmount);
+        uint256 rightTakerAssetAmountRemaining = safeSub(rightOrder.takerAssetAmount, rightOrderTakerAssetFilledAmount);
+        uint256 leftTakerAssetFilledAmount;
+        uint256 rightTakerAssetFilledAmount;
         if (
             safeMul(leftTakerAssetAmountRemaining, rightOrder.takerAssetAmount) <=
             safeMul(rightTakerAssetAmountRemaining, rightOrder.makerAssetAmount)
         ) {
             // Left order will be fully filled: maximally fill left
-            leftOrderAmountToFill = leftTakerAssetAmountRemaining;
+            leftTakerAssetFilledAmount = leftTakerAssetAmountRemaining;
 
             // The right order receives an amount proportional to how much was spent.
             // TODO: Can we ensure rounding error is in the correct direction?
-            rightOrderAmountToFill = safeGetPartialAmount(
+            rightTakerAssetFilledAmount = getPartialAmount(
                 rightOrder.takerAssetAmount,
                 rightOrder.makerAssetAmount,
-                leftOrderAmountToFill
+                leftTakerAssetFilledAmount
             );
         } else {
             // Right order will be fully filled: maximally fill right
-            rightOrderAmountToFill = rightTakerAssetAmountRemaining;
+            rightTakerAssetFilledAmount = rightTakerAssetAmountRemaining;
 
             // The left order receives an amount proportional to how much was spent.
             // TODO: Can we ensure rounding error is in the correct direction?
-            leftOrderAmountToFill = safeGetPartialAmount(
+            leftTakerAssetFilledAmount = getPartialAmount(
                 rightOrder.makerAssetAmount,
                 rightOrder.takerAssetAmount,
-                rightOrderAmountToFill
+                rightTakerAssetFilledAmount
             );
         }
 
         // Calculate fill results for left order
-        uint8 status;
-        (status, matchedFillResults.left) = calculateFillResults(
+        matchedFillResults.left = calculateFillResults(
             leftOrder,
-            leftOrderStatus,
-            leftOrderFilledAmount,
-            leftOrderAmountToFill
-        );
-        require(
-            status == uint8(Status.SUCCESS),
-            FAILED_TO_CALCULATE_FILL_RESULTS_FOR_LEFT_ORDER
+            leftTakerAssetFilledAmount
         );
 
         // Calculate fill results for right order
-        (status, matchedFillResults.right) = calculateFillResults(
+        matchedFillResults.right = calculateFillResults(
             rightOrder,
-            rightOrderStatus,
-            rightOrderFilledAmount,
-            rightOrderAmountToFill
-        );
-        require(
-            status == uint8(Status.SUCCESS),
-            FAILED_TO_CALCULATE_FILL_RESULTS_FOR_RIGHT_ORDER
+            rightTakerAssetFilledAmount
         );
 
         // Calculate amount given to taker
-        matchedFillResults.takerFillAmount = safeSub(
+        matchedFillResults.leftMakerAssetSpreadAmount = safeSub(
             matchedFillResults.left.makerAssetFilledAmount,
             matchedFillResults.right.takerAssetFilledAmount
         );
 
-        // Validate the fill results
-        assertValidMatchResults(matchedFillResults);
-
         // Return fill results
         return matchedFillResults;
     }
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinSettlement.sol b/packages/contracts/src/contracts/current/protocol/Exchange/MixinSettlement.sol
index 7c03bde75..646d3ed58 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinSettlement.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/MixinSettlement.sol
@@ -19,17 +19,16 @@
 pragma solidity ^0.4.24;
 pragma experimental ABIEncoderV2;
 
-import "./mixins/MSettlement.sol";
-import "./mixins/MAssetProxyDispatcher.sol";
-import "./libs/LibOrder.sol";
 import "./libs/LibMath.sol";
-import "./libs/LibExchangeErrors.sol";
 import "./libs/LibFillResults.sol";
+import "./libs/LibOrder.sol";
+import "./libs/LibExchangeErrors.sol";
 import "./mixins/MMatchOrders.sol";
+import "./mixins/MSettlement.sol";
+import "./mixins/MAssetProxyDispatcher.sol";
 
 contract MixinSettlement is
     LibMath,
-    LibFillResults,
     LibExchangeErrors,
     MMatchOrders,
     MSettlement,
@@ -65,7 +64,7 @@ contract MixinSettlement is
     function settleOrder(
         LibOrder.Order memory order,
         address takerAddress,
-        FillResults memory fillResults
+        LibFillResults.FillResults memory fillResults
     )
         internal
     {
@@ -104,7 +103,7 @@ contract MixinSettlement is
         LibOrder.Order memory leftOrder,
         LibOrder.Order memory rightOrder,
         address takerAddress,
-        MatchedFillResults memory matchedFillResults
+        LibFillResults.MatchedFillResults memory matchedFillResults
     )
         internal
     {
@@ -125,7 +124,7 @@ contract MixinSettlement is
             leftOrder.makerAssetData,
             leftOrder.makerAddress,
             takerAddress,
-            matchedFillResults.takerFillAmount
+            matchedFillResults.leftMakerAssetSpreadAmount
         );
 
         // Maker fees
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinSignatureValidator.sol b/packages/contracts/src/contracts/current/protocol/Exchange/MixinSignatureValidator.sol
index 79dc87af0..48a0c5552 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinSignatureValidator.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/MixinSignatureValidator.sol
@@ -18,12 +18,12 @@
 
 pragma solidity ^0.4.24;
 
+import "../../utils/LibBytes/LibBytes.sol";
+import "./libs/LibExchangeErrors.sol";
 import "./mixins/MSignatureValidator.sol";
 import "./mixins/MTransactions.sol";
 import "./interfaces/IWallet.sol";
 import "./interfaces/IValidator.sol";
-import "./libs/LibExchangeErrors.sol";
-import "../../utils/LibBytes/LibBytes.sol";
 
 contract MixinSignatureValidator is
     LibBytes,
@@ -31,6 +31,9 @@ contract MixinSignatureValidator is
     MSignatureValidator,
     MTransactions
 {
+    // Personal message headers
+    string constant ETH_PERSONAL_MESSAGE = "\x19Ethereum Signed Message:\n32";
+    string constant TREZOR_PERSONAL_MESSAGE = "\x19Ethereum Signed Message:\n\x41";
 
     // Mapping of hash => signer => signed
     mapping (bytes32 => mapping (address => bool)) public preSigned;
@@ -51,7 +54,7 @@ contract MixinSignatureValidator is
     {
         require(
             isValidSignature(hash, signer, signature),
-            SIGNATURE_VALIDATION_FAILED
+            INVALID_SIGNATURE
         );
         preSigned[hash][signer] = true;
     }
@@ -85,8 +88,8 @@ contract MixinSignatureValidator is
     {
         // TODO: Domain separation: make hash depend on role. (Taker sig should not be valid as maker sig, etc.)
         require(
-            signature.length >= 1,
-            INVALID_SIGNATURE_LENGTH
+            signature.length > 0,
+            LENGTH_GREATER_THAN_0_REQUIRED
         );
 
         // Pop last byte off of signature byte array.
@@ -104,7 +107,7 @@ contract MixinSignatureValidator is
         // it an explicit option. This aids testing and analysis. It is
         // also the initialization value for the enum type.
         if (signatureType == SignatureType.Illegal) {
-            revert(ILLEGAL_SIGNATURE_TYPE);
+            revert(SIGNATURE_ILLEGAL);
 
         // Always invalid signature.
         // Like Illegal, this is always implicitly available and therefore
@@ -113,7 +116,7 @@ contract MixinSignatureValidator is
         } else if (signatureType == SignatureType.Invalid) {
             require(
                 signature.length == 0,
-                INVALID_SIGNATURE_LENGTH
+                LENGTH_0_REQUIRED
             );
             isValid = false;
             return isValid;
@@ -122,7 +125,7 @@ contract MixinSignatureValidator is
         } else if (signatureType == SignatureType.EIP712) {
             require(
                 signature.length == 65,
-                INVALID_SIGNATURE_LENGTH
+                LENGTH_65_REQUIRED
             );
             v = uint8(signature[0]);
             r = readBytes32(signature, 1);
@@ -135,13 +138,13 @@ contract MixinSignatureValidator is
         } else if (signatureType == SignatureType.EthSign) {
             require(
                 signature.length == 65,
-                INVALID_SIGNATURE_LENGTH
+                LENGTH_65_REQUIRED
             );
             v = uint8(signature[0]);
             r = readBytes32(signature, 1);
             s = readBytes32(signature, 33);
             recovered = ecrecover(
-                keccak256("\x19Ethereum Signed Message:\n32", hash),
+                keccak256(abi.encodePacked(ETH_PERSONAL_MESSAGE, hash)),
                 v,
                 r,
                 s
@@ -160,7 +163,7 @@ contract MixinSignatureValidator is
         } else if (signatureType == SignatureType.Caller) {
             require(
                 signature.length == 0,
-                INVALID_SIGNATURE_LENGTH
+                LENGTH_0_REQUIRED
             );
             isValid = signer == msg.sender;
             return isValid;
@@ -208,13 +211,13 @@ contract MixinSignatureValidator is
         } else if (signatureType == SignatureType.Trezor) {
             require(
                 signature.length == 65,
-                INVALID_SIGNATURE_LENGTH
+                LENGTH_65_REQUIRED
             );
             v = uint8(signature[0]);
             r = readBytes32(signature, 1);
             s = readBytes32(signature, 33);
             recovered = ecrecover(
-                keccak256("\x19Ethereum Signed Message:\n\x41", hash),
+                keccak256(abi.encodePacked(TREZOR_PERSONAL_MESSAGE, hash)),
                 v,
                 r,
                 s
@@ -233,6 +236,6 @@ contract MixinSignatureValidator is
         // that we currently support. In this case returning false
         // may lead the caller to incorrectly believe that the
         // signature was invalid.)
-        revert(UNSUPPORTED_SIGNATURE_TYPE);
+        revert(SIGNATURE_UNSUPPORTED);
     }
 }
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinTransactions.sol b/packages/contracts/src/contracts/current/protocol/Exchange/MixinTransactions.sol
index d153dfa5c..30b0102fd 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinTransactions.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/MixinTransactions.sol
@@ -17,9 +17,9 @@
 */
 pragma solidity ^0.4.24;
 
+import "./libs/LibExchangeErrors.sol";
 import "./mixins/MSignatureValidator.sol";
 import "./mixins/MTransactions.sol";
-import "./libs/LibExchangeErrors.sol";
 
 contract MixinTransactions is
     LibExchangeErrors,
@@ -50,29 +50,29 @@ contract MixinTransactions is
         // Prevent reentrancy
         require(
             currentContextAddress == address(0),
-            REENTRANCY_NOT_ALLOWED
+            REENTRANCY_ILLEGAL
         );
 
         // Calculate transaction hash
-        bytes32 transactionHash = keccak256(
+        bytes32 transactionHash = keccak256(abi.encodePacked(
             address(this),
             signer,
             salt,
             data
-        );
+        ));
 
         // Validate transaction has not been executed
         require(
             !transactions[transactionHash],
-            DUPLICATE_TRANSACTION_HASH
+            INVALID_TX_HASH
         );
 
-        // TODO: is SignatureType.Caller necessary if we make this check?
+        // Transaction always valid if signer is sender of transaction
         if (signer != msg.sender) {
             // Validate signature
             require(
                 isValidSignature(transactionHash, signer, signature),
-                SIGNATURE_VALIDATION_FAILED
+                INVALID_TX_SIGNATURE
             );
 
             // Set the current transaction signer
@@ -83,7 +83,7 @@ contract MixinTransactions is
         transactions[transactionHash] = true;
         require(
             address(this).delegatecall(data),
-            TRANSACTION_EXECUTION_FAILED
+            FAILED_EXECUTION
         );
 
         // Reset current transaction signer
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinWrapperFunctions.sol b/packages/contracts/src/contracts/current/protocol/Exchange/MixinWrapperFunctions.sol
index 15f1a2e0b..0ad0710ce 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinWrapperFunctions.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/MixinWrapperFunctions.sol
@@ -20,17 +20,15 @@ pragma solidity ^0.4.24;
 pragma experimental ABIEncoderV2;
 
 import "../../utils/LibBytes/LibBytes.sol";
-import "./mixins/MExchangeCore.sol";
 import "./libs/LibMath.sol";
 import "./libs/LibOrder.sol";
 import "./libs/LibFillResults.sol";
 import "./libs/LibExchangeErrors.sol";
+import "./mixins/MExchangeCore.sol";
 
 contract MixinWrapperFunctions is
-    SafeMath,
     LibBytes,
     LibMath,
-    LibOrder,
     LibFillResults,
     LibExchangeErrors,
     MExchangeCore
@@ -40,7 +38,7 @@ contract MixinWrapperFunctions is
     /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
     /// @param signature Proof that order has been created by maker.
     function fillOrKillOrder(
-        Order memory order,
+        LibOrder.Order memory order,
         uint256 takerAssetFillAmount,
         bytes memory signature)
         public
@@ -65,7 +63,7 @@ contract MixinWrapperFunctions is
     /// @param signature Proof that order has been created by maker.
     /// @return Amounts filled and fees paid by maker and taker.
     function fillOrderNoThrow(
-        Order memory order,
+        LibOrder.Order memory order,
         uint256 takerAssetFillAmount,
         bytes memory signature)
         public
@@ -264,7 +262,7 @@ contract MixinWrapperFunctions is
     /// @param takerAssetFillAmounts Array of desired amounts of takerAsset to sell in orders.
     /// @param signatures Proofs that orders have been created by makers.
     function batchFillOrders(
-        Order[] memory orders,
+        LibOrder.Order[] memory orders,
         uint256[] memory takerAssetFillAmounts,
         bytes[] memory signatures)
         public
@@ -283,7 +281,7 @@ contract MixinWrapperFunctions is
     /// @param takerAssetFillAmounts Array of desired amounts of takerAsset to sell in orders.
     /// @param signatures Proofs that orders have been created by makers.
     function batchFillOrKillOrders(
-        Order[] memory orders,
+        LibOrder.Order[] memory orders,
         uint256[] memory takerAssetFillAmounts,
         bytes[] memory signatures)
         public
@@ -303,7 +301,7 @@ contract MixinWrapperFunctions is
     /// @param takerAssetFillAmounts Array of desired amounts of takerAsset to sell in orders.
     /// @param signatures Proofs that orders have been created by makers.
     function batchFillOrdersNoThrow(
-        Order[] memory orders,
+        LibOrder.Order[] memory orders,
         uint256[] memory takerAssetFillAmounts,
         bytes[] memory signatures)
         public
@@ -323,7 +321,7 @@ contract MixinWrapperFunctions is
     /// @param signatures Proofs that orders have been created by makers.
     /// @return Amounts filled and fees paid by makers and taker.
     function marketSellOrders(
-        Order[] memory orders,
+        LibOrder.Order[] memory orders,
         uint256 takerAssetFillAmount,
         bytes[] memory signatures)
         public
@@ -366,7 +364,7 @@ contract MixinWrapperFunctions is
     /// @param signatures Proofs that orders have been signed by makers.
     /// @return Amounts filled and fees paid by makers and taker.
     function marketSellOrdersNoThrow(
-        Order[] memory orders,
+        LibOrder.Order[] memory orders,
         uint256 takerAssetFillAmount,
         bytes[] memory signatures)
         public
@@ -408,7 +406,7 @@ contract MixinWrapperFunctions is
     /// @param signatures Proofs that orders have been signed by makers.
     /// @return Amounts filled and fees paid by makers and taker.
     function marketBuyOrders(
-        Order[] memory orders,
+        LibOrder.Order[] memory orders,
         uint256 makerAssetFillAmount,
         bytes[] memory signatures)
         public
@@ -459,7 +457,7 @@ contract MixinWrapperFunctions is
     /// @param signatures Proofs that orders have been signed by makers.
     /// @return Amounts filled and fees paid by makers and taker.
     function marketBuyOrdersNoThrow(
-        Order[] memory orders,
+        LibOrder.Order[] memory orders,
         uint256 makerAssetFillAmount,
         bytes[] memory signatures)
         public
@@ -505,7 +503,7 @@ contract MixinWrapperFunctions is
 
     /// @dev Synchronously cancels multiple orders in a single transaction.
     /// @param orders Array of order specifications.
-    function batchCancelOrders(Order[] memory orders)
+    function batchCancelOrders(LibOrder.Order[] memory orders)
         public
     {
         for (uint256 i = 0; i < orders.length; i++) {
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IExchangeCore.sol b/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IExchangeCore.sol
index fc0157d75..7ca2dd052 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IExchangeCore.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IExchangeCore.sol
@@ -37,17 +37,15 @@ contract IExchangeCore {
     function fillOrder(
         LibOrder.Order memory order,
         uint256 takerAssetFillAmount,
-        bytes memory signature)
+        bytes memory signature
+    )
         public
         returns (LibFillResults.FillResults memory fillResults);
 
     /// @dev After calling, the order can not be filled anymore.
     /// @param order Order struct containing order specifications.
-    /// @return True if the order state changed to cancelled.
-    ///         False if the transaction was already cancelled or expired.
     function cancelOrder(LibOrder.Order memory order)
-        public
-        returns (bool);
+        public;
 
     /// @dev Gets information about an order: status, hash, and amount filled.
     /// @param order Order to gather information on.
@@ -57,24 +55,4 @@ contract IExchangeCore {
         public
         view
         returns (LibOrder.OrderInfo memory orderInfo);
-
-    /// @dev Calculates amounts filled and fees paid by maker and taker.
-    /// @param order to be filled.
-    /// @param orderStatus Status of order to be filled.
-    /// @param orderTakerAssetFilledAmount Amount of order already filled.
-    /// @param takerAssetFillAmount Desired amount of order to fill by taker.
-    /// @return status Return status of calculating fill amounts. Returns Status.SUCCESS on success.
-    /// @return fillResults Amounts filled and fees paid by maker and taker.
-    function calculateFillResults(
-        LibOrder.Order memory order,
-        uint8 orderStatus,
-        uint256 orderTakerAssetFilledAmount,
-        uint256 takerAssetFillAmount
-    )
-        public
-        pure
-        returns (
-            uint8 status,
-            LibFillResults.FillResults memory fillResults
-        );
 }
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibExchangeErrors.sol b/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibExchangeErrors.sol
index 7d67e5080..2b4bbeec4 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibExchangeErrors.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibExchangeErrors.sol
@@ -19,43 +19,44 @@
 pragma solidity ^0.4.24;
 
 contract LibExchangeErrors {
-
-    // Core revert reasons
-    string constant GT_ZERO_AMOUNT_REQUIRED = "Amount must be greater than 0.";
-    string constant SIGNATURE_VALIDATION_FAILED = "Signature validation failed.";
-    string constant INVALID_SENDER = "Invalid `msg.sender`.";
-    string constant INVALID_CONTEXT = "Function called in an invalid context.";
-    string constant INVALID_NEW_MAKER_EPOCH = "Specified salt must be greater than or equal to existing makerEpoch.";
-
-    // Order revert reasons
-    string constant INVALID_ORDER_TAKER_ASSET_AMOUNT = "Invalid order taker asset amount: expected a non-zero value.";
-    string constant INVALID_ORDER_MAKER_ASSET_AMOUNT = "Invalid order maker asset amount: expected a non-zero value.";
-
-    // Transaction revert reasons
-    string constant REENTRANCY_NOT_ALLOWED = "`executeTransaction` is not allowed to call itself recursively.";
-    string constant DUPLICATE_TRANSACTION_HASH = "Transaction has already been executed.";
-    string constant TRANSACTION_EXECUTION_FAILED = "Transaction execution failed.";
-
-    // Wrapper revert reasons
-    string constant COMPLETE_FILL_FAILED = "Desired fill amount could not be completely filled.";
-    string constant ASSET_DATA_MISMATCH = "Asset data must be the same for each order.";
-
-    // Asset proxy dispatcher revert reasons
-    string constant GT_ZERO_LENGTH_REQUIRED = "Length must be greater than 0.";
-    string constant OLD_ASSET_PROXY_MISMATCH = "Old asset proxy does not match asset proxy at given id.";
-    string constant NEW_ASSET_PROXY_MISMATCH = "New asset proxy id does not match given id.";
-
-    // Signature validator revert reasons
-    string constant INVALID_SIGNATURE_LENGTH = "Invalid signature length.";
-    string constant ILLEGAL_SIGNATURE_TYPE = "Illegal signature type.";
-    string constant UNSUPPORTED_SIGNATURE_TYPE = "Unsupported signature type.";
-
-    // Order matching revert reasons
-    string constant ASSET_MISMATCH_MAKER_TAKER = "Left order maker asset is different from right order taker asset.";
-    string constant ASSET_MISMATCH_TAKER_MAKER = "Left order taker asset is different from right order maker asset.";
-    string constant NEGATIVE_SPREAD = "Matched orders must have a positive spread.";
-    string constant MISCALCULATED_TRANSFER_AMOUNTS = "A miscalculation occurred: the left maker would receive more than the right maker would spend.";
-    string constant ROUNDING_ERROR_TRANSFER_AMOUNTS = "A rounding error occurred when calculating transfer amounts for matched orders.";
-    string constant FAILED_TO_CALCULATE_FILL_RESULTS_FOR_LEFT_ORDER = "Failed to calculate fill results for left order.";
-    string constant FAILED_TO_CALCULATE_FILL_RESULTS_FOR_RIGHT_ORDER = "Failed to calculate fill results for right order.";
+    /// Order validation errors ///
+    string constant ORDER_UNFILLABLE = "ORDER_UNFILLABLE";                  // Order cannot be filled.
+    string constant INVALID_MAKER = "INVALID_MAKER";                        // Invalid makerAddress.
+    string constant INVALID_TAKER = "INVALID_TAKER";                        // Invalid takerAddress.
+    string constant INVALID_SENDER = "INVALID_SENDER";                      // Invalid `msg.sender`.
+    string constant INVALID_ORDER_SIGNATURE = "INVALID_ORDER_SIGNATURE";    // Signature validation failed. 
+    string constant ASSET_DATA_MISMATCH = "ASSET_DATA_MISMATCH";            // Asset data must be the same for each order. 
+    
+    /// fillOrder validation errors ///
+    string constant INVALID_TAKER_AMOUNT = "INVALID_TAKER_AMOUNT";          // takerAssetFillAmount cannot equal 0.
+    string constant ROUNDING_ERROR = "ROUNDING_ERROR";                      // Rounding error greater than 0.1% of takerAssetFillAmount. 
+    
+    /// Signature validation errors ///
+    string constant INVALID_SIGNATURE = "INVALID_SIGNATURE";                // Signature validation failed. 
+    string constant SIGNATURE_ILLEGAL = "SIGNATURE_ILLEGAL";                // Signature type is illegal.
+    string constant SIGNATURE_UNSUPPORTED = "SIGNATURE_UNSUPPORTED";        // Signature type unsupported.
+    
+    /// cancelOrdersUptTo errors ///
+    string constant INVALID_NEW_MAKER_EPOCH = "INVALID_NEW_MAKER_EPOCH";    // Specified salt must be greater than or equal to existing makerEpoch.
+
+    /// fillOrKillOrder errors ///
+    string constant COMPLETE_FILL_FAILED = "COMPLETE_FILL_FAILED";          // Desired takerAssetFillAmount could not be completely filled. 
+
+    /// matchOrders errors ///
+    string constant NEGATIVE_SPREAD_REQUIRED = "NEGATIVE_SPREAD_REQUIRED";  // Matched orders must have a negative spread.
+
+    /// Transaction errors ///
+    string constant REENTRANCY_ILLEGAL = "REENTRANCY_ILLEGAL";              // Recursive reentrancy is not allowed. 
+    string constant INVALID_TX_HASH = "INVALID_TX_HASH";                    // Transaction has already been executed. 
+    string constant INVALID_TX_SIGNATURE = "INVALID_TX_SIGNATURE";          // Signature validation failed. 
+    string constant FAILED_EXECUTION = "FAILED_EXECUTION";                  // Transaction execution failed. 
+    
+    /// registerAssetProxy errors ///
+    string constant ASSET_PROXY_MISMATCH = "ASSET_PROXY_MISMATCH";          // oldAssetProxy proxy does not match currentAssetProxy. 
+    string constant ASSET_PROXY_ID_MISMATCH = "ASSET_PROXY_ID_MISMATCH";    // newAssetProxyId does not match given assetProxyId.
+
+    /// Length validation errors ///
+    string constant LENGTH_GREATER_THAN_0_REQUIRED = "LENGTH_GREATER_THAN_0_REQUIRED"; // Byte array must have a length greater than 0.
+    string constant LENGTH_0_REQUIRED = "LENGTH_1_REQUIRED";                // Byte array must have a length of 1.
+    string constant LENGTH_65_REQUIRED = "LENGTH_66_REQUIRED";              // Byte array must have a length of 66.
 }
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibFillResults.sol b/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibFillResults.sol
index aa54598fa..b7550d6d2 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibFillResults.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibFillResults.sol
@@ -32,9 +32,9 @@ contract LibFillResults is
     }
 
     struct MatchedFillResults {
-        LibFillResults.FillResults left;
-        LibFillResults.FillResults right;
-        uint256 takerFillAmount;
+        FillResults left;
+        FillResults right;
+        uint256 leftMakerAssetSpreadAmount;
     }
 
     /// @dev Adds properties of both FillResults instances.
@@ -50,19 +50,4 @@ contract LibFillResults is
         totalFillResults.makerFeePaid = safeAdd(totalFillResults.makerFeePaid, singleFillResults.makerFeePaid);
         totalFillResults.takerFeePaid = safeAdd(totalFillResults.takerFeePaid, singleFillResults.takerFeePaid);
     }
-
-    /// @dev Returns a null fill results struct
-    function getNullFillResults()
-        internal
-        pure
-        returns (FillResults memory)
-    {
-        // returns zeroed out FillResults instance
-        return FillResults({
-            makerAssetFilledAmount: 0,
-            takerAssetFilledAmount: 0,
-            makerFeePaid: 0,
-            takerFeePaid: 0
-        });
-    }
 }
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibMath.sol b/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibMath.sol
index ea8c138d6..233547b9f 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibMath.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibMath.sol
@@ -45,26 +45,6 @@ contract LibMath is
         return partialAmount;
     }
 
-    /// @dev Calculates partial value given a numerator and denominator.
-    ///      Throws if there is a rounding error.
-    /// @param numerator Numerator.
-    /// @param denominator Denominator.
-    /// @param target Value to calculate partial of.
-    /// @return Partial value of target.
-    function safeGetPartialAmount(
-        uint256 numerator,
-        uint256 denominator,
-        uint256 target)
-        internal pure
-        returns (uint256 partialAmount)
-    {
-        require(
-            !isRoundingError(numerator, denominator, target),
-            ROUNDING_ERROR_ON_PARTIAL_AMOUNT
-        );
-        return getPartialAmount(numerator, denominator, target);
-    }
-
     /// @dev Checks if rounding error > 0.1%.
     /// @param numerator Numerator.
     /// @param denominator Denominator.
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibOrder.sol b/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibOrder.sol
index ed7f9391d..05ea27ffc 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibOrder.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibOrder.sol
@@ -20,11 +20,11 @@ pragma solidity ^0.4.24;
 
 contract LibOrder {
 
-    bytes32 constant DOMAIN_SEPARATOR_SCHEMA_HASH = keccak256(
+    bytes32 constant DOMAIN_SEPARATOR_SCHEMA_HASH = keccak256(abi.encodePacked(
         "DomainSeparator(address contract)"
-    );
+    ));
 
-    bytes32 constant ORDER_SCHEMA_HASH = keccak256(
+    bytes32 constant ORDER_SCHEMA_HASH = keccak256(abi.encodePacked(
         "Order(",
         "address makerAddress,",
         "address takerAddress,",
@@ -39,7 +39,19 @@ contract LibOrder {
         "bytes makerAssetData,",
         "bytes takerAssetData,",
         ")"
-    );
+    ));
+
+    // A valid order remains fillable until it is expired, fully filled, or cancelled.
+    // An order's state is unaffected by external factors, like account balances.
+    enum OrderStatus {
+        INVALID,                     // Default value
+        INVALID_MAKER_ASSET_AMOUNT,  // Order does not have a valid maker asset amount
+        INVALID_TAKER_ASSET_AMOUNT,  // Order does not have a valid taker asset amount
+        FILLABLE,                    // Order is fillable
+        EXPIRED,                     // Order has already expired
+        FULLY_FILLED,                // Order is fully filled
+        CANCELLED                    // Order has been cancelled
+    }
 
     struct Order {
         address makerAddress;
@@ -75,11 +87,11 @@ contract LibOrder {
     {
         // TODO: EIP712 is not finalized yet
         // Source: https://github.com/ethereum/EIPs/pull/712
-        orderHash = keccak256(
+        orderHash = keccak256(abi.encodePacked(
             DOMAIN_SEPARATOR_SCHEMA_HASH,
-            keccak256(address(this)),
+            keccak256(abi.encodePacked(address(this))),
             ORDER_SCHEMA_HASH,
-            keccak256(
+            keccak256(abi.encodePacked(
                 order.makerAddress,
                 order.takerAddress,
                 order.feeRecipientAddress,
@@ -90,10 +102,10 @@ contract LibOrder {
                 order.takerFee,
                 order.expirationTimeSeconds,
                 order.salt,
-                keccak256(order.makerAssetData),
-                keccak256(order.takerAssetData)
-            )
-        );
+                keccak256(abi.encodePacked(order.makerAssetData)),
+                keccak256(abi.encodePacked(order.takerAssetData))
+            ))
+        ));
         return orderHash;
     }
 }
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibStatus.sol b/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibStatus.sol
deleted file mode 100644
index f72b7d65f..000000000
--- a/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibStatus.sol
+++ /dev/null
@@ -1,51 +0,0 @@
-/*
-
-  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;
-
-contract LibStatus {
-
-    // Exchange Status Codes
-    enum Status {
-        /// Default Status ///
-        INVALID,                                // General invalid status
-
-        /// General Exchange Statuses ///
-        SUCCESS,                                // Indicates a successful operation
-        ROUNDING_ERROR_TOO_LARGE,               // Rounding error too large
-        INSUFFICIENT_BALANCE_OR_ALLOWANCE,      // Insufficient balance or allowance for token transfer
-        TAKER_ASSET_FILL_AMOUNT_TOO_LOW,        // takerAssetFillAmount is <= 0
-        INVALID_SIGNATURE,                      // Invalid signature
-        INVALID_SENDER,                         // Invalid sender
-        INVALID_TAKER,                          // Invalid taker
-        INVALID_MAKER,                          // Invalid maker
-
-        /// Order State Statuses ///
-        // A valid order remains fillable until it is expired, fully filled, or cancelled.
-        // An order's state is unaffected by external factors, like account balances.
-        ORDER_INVALID_MAKER_ASSET_AMOUNT,       // Order does not have a valid maker asset amount
-        ORDER_INVALID_TAKER_ASSET_AMOUNT,       // Order does not have a valid taker asset amount
-        ORDER_FILLABLE,                         // Order is fillable
-        ORDER_EXPIRED,                          // Order has already expired
-        ORDER_FULLY_FILLED,                     // Order is fully filled
-        ORDER_CANCELLED                         // Order has been cancelled
-    }
-
-    event ExchangeStatus(uint8 indexed statusId, bytes32 indexed orderHash);
-}
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MExchangeCore.sol b/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MExchangeCore.sol
index ae1e50637..de7c4d3af 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MExchangeCore.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MExchangeCore.sol
@@ -26,7 +26,6 @@ import "../interfaces/IExchangeCore.sol";
 contract MExchangeCore is
     IExchangeCore
 {
-
     // Fill event is emitted whenever an order is filled.
     event Fill(
         address indexed makerAddress,
@@ -56,25 +55,6 @@ contract MExchangeCore is
         uint256 makerEpoch
     );
 
-    /// @dev Validates context for fillOrder. Succeeds or throws.
-    /// @param order to be filled.
-    /// @param orderStatus Status of order to be filled.
-    /// @param orderHash Hash of order to be filled.
-    /// @param takerAddress Address of order taker.
-    /// @param orderTakerAssetFilledAmount Amount of order already filled.
-    /// @param takerAssetFillAmount Desired amount of order to fill by taker.
-    /// @param signature Proof that the orders was created by its maker.
-    function assertValidFill(
-        LibOrder.Order memory order,
-        uint8 orderStatus,
-        bytes32 orderHash,
-        address takerAddress,
-        uint256 orderTakerAssetFilledAmount,
-        uint256 takerAssetFillAmount,
-        bytes memory signature
-    )
-        internal;
-
     /// @dev Updates state with results of a fill order.
     /// @param order that was filled.
     /// @param takerAddress Address of taker who filled the order.
@@ -89,29 +69,55 @@ contract MExchangeCore is
     )
         internal;
 
-    /// @dev Validates context for cancelOrder. Succeeds or throws.
-    /// @param order that was cancelled.
-    /// @param orderStatus Status of order that was cancelled.
-    /// @param orderHash Hash of order that was cancelled.
-    function assertValidCancel(
-        LibOrder.Order memory order,
-        uint8 orderStatus,
-        bytes32 orderHash
-    )
-        internal;
-
     /// @dev Updates state with results of cancelling an order.
     ///      State is only updated if the order is currently fillable.
     ///      Otherwise, updating state would have no effect.
     /// @param order that was cancelled.
-    /// @param orderStatus Status of order that was cancelled.
     /// @param orderHash Hash of order that was cancelled.
-    /// @return stateUpdated Returns true only if state was updated.
     function updateCancelledState(
         LibOrder.Order memory order,
-        uint8 orderStatus,
         bytes32 orderHash
     )
+        internal;
+
+    /// @dev Validates context for fillOrder. Succeeds or throws.
+    /// @param order to be filled.
+    /// @param orderInfo Status, orderHash, and amount already filled of order.
+    /// @param takerAddress Address of order taker.
+    /// @param takerAssetFillAmount Desired amount of order to fill by taker.
+    /// @param takerAssetFilledAmount Amount of takerAsset that will be filled.
+    /// @param signature Proof that the orders was created by its maker.
+    function assertValidFill(
+        LibOrder.Order memory order,
+        LibOrder.OrderInfo memory orderInfo,
+        address takerAddress,
+        uint256 takerAssetFillAmount,
+        uint256 takerAssetFilledAmount,
+        bytes memory signature
+    )
+        internal
+        view;
+
+
+    /// @dev Validates context for cancelOrder. Succeeds or throws.
+    /// @param order to be cancelled.
+    /// @param orderInfo OrderStatus, orderHash, and amount already filled of order.
+    function assertValidCancel(
+        LibOrder.Order memory order,
+        LibOrder.OrderInfo memory orderInfo
+    )
+        internal
+        view;
+
+    /// @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 calculateFillResults(
+        LibOrder.Order memory order,
+        uint256 takerAssetFilledAmount
+    )
         internal
-        returns (bool stateUpdated);
+        pure
+        returns (LibFillResults.FillResults memory fillResults);
 }
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MMatchOrders.sol b/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MMatchOrders.sol
index 7dd608cf2..e52963a26 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MMatchOrders.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MMatchOrders.sol
@@ -20,7 +20,6 @@ pragma experimental ABIEncoderV2;
 
 import "../libs/LibOrder.sol";
 import "../libs/LibFillResults.sol";
-import "./MExchangeCore.sol";
 import "../interfaces/IMatchOrders.sol";
 
 contract MMatchOrders is
@@ -34,12 +33,8 @@ contract MMatchOrders is
         LibOrder.Order memory leftOrder,
         LibOrder.Order memory rightOrder
     )
-        internal;
-
-    /// @dev Validates matched fill results. Succeeds or throws.
-    /// @param matchedFillResults Amounts to fill and fees to pay by maker and taker of matched orders.
-    function assertValidMatchResults(LibFillResults.MatchedFillResults memory matchedFillResults)
-        internal;
+        internal
+        pure;
 
     /// @dev Calculates fill amounts for the matched orders.
     ///      Each order is filled at their respective price point. However, the calculations are
@@ -47,19 +42,16 @@ contract MMatchOrders is
     ///      The profit made by the leftOrder order goes to the taker (who matched the two orders).
     /// @param leftOrder First order to match.
     /// @param rightOrder Second order to match.
-    /// @param leftOrderStatus Order status of left order.
-    /// @param rightOrderStatus Order status of right order.
-    /// @param leftOrderFilledAmount Amount of left order already filled.
-    /// @param rightOrderFilledAmount Amount of right order already filled.
+    /// @param leftOrderTakerAssetFilledAmount Amount of left order already filled.
+    /// @param rightOrderTakerAssetFilledAmount Amount of right order already filled.
     /// @param matchedFillResults Amounts to fill and fees to pay by maker and taker of matched orders.
     function calculateMatchedFillResults(
         LibOrder.Order memory leftOrder,
         LibOrder.Order memory rightOrder,
-        uint8 leftOrderStatus,
-        uint8 rightOrderStatus,
-        uint256 leftOrderFilledAmount,
-        uint256 rightOrderFilledAmount
+        uint256 leftOrderTakerAssetFilledAmount,
+        uint256 rightOrderTakerAssetFilledAmount
     )
         internal
+        pure
         returns (LibFillResults.MatchedFillResults memory matchedFillResults);
 }
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MSettlement.sol b/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MSettlement.sol
index 50b62e79f..2c403162f 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MSettlement.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MSettlement.sol
@@ -19,7 +19,6 @@
 pragma solidity ^0.4.24;
 
 import "../libs/LibOrder.sol";
-import "./MMatchOrders.sol";
 import "../libs/LibFillResults.sol";
 
 contract MSettlement {
diff --git a/packages/contracts/src/contracts/current/test/TestLibs/TestLibs.sol b/packages/contracts/src/contracts/current/test/TestLibs/TestLibs.sol
index bd01277dd..47ce0dcf3 100644
--- a/packages/contracts/src/contracts/current/test/TestLibs/TestLibs.sol
+++ b/packages/contracts/src/contracts/current/test/TestLibs/TestLibs.sol
@@ -71,7 +71,7 @@ contract TestLibs is
 
     function getOrderSchemaHash()
         public
-        view
+        pure
         returns (bytes32)
     {
         return ORDER_SCHEMA_HASH;
@@ -79,7 +79,7 @@ contract TestLibs is
 
     function getDomainSeparatorSchemaHash()
         public
-        view
+        pure
         returns (bytes32)
     {
         return DOMAIN_SEPARATOR_SCHEMA_HASH;
diff --git a/packages/contracts/src/utils/match_order_tester.ts b/packages/contracts/src/utils/match_order_tester.ts
index 09c0d8083..6170188bc 100644
--- a/packages/contracts/src/utils/match_order_tester.ts
+++ b/packages/contracts/src/utils/match_order_tester.ts
@@ -26,7 +26,6 @@ import {
     ContractName,
     ERC20BalancesByOwner,
     ERC721TokenIdsByOwner,
-    ExchangeStatus,
     TransferAmountsByMatchOrders as TransferAmounts,
 } from '../utils/types';
 import { provider, web3Wrapper } from '../utils/web3_wrapper';
diff --git a/packages/contracts/src/utils/types.ts b/packages/contracts/src/utils/types.ts
index 6340c4a51..360e1fdbc 100644
--- a/packages/contracts/src/utils/types.ts
+++ b/packages/contracts/src/utils/types.ts
@@ -69,22 +69,14 @@ export interface Token {
     swarmHash: string;
 }
 
-export enum ExchangeStatus {
+export enum OrderStatus {
     INVALID,
-    SUCCESS,
-    ROUNDING_ERROR_TOO_LARGE,
-    INSUFFICIENT_BALANCE_OR_ALLOWANCE,
-    TAKER_ASSET_FILL_AMOUNT_TOO_LOW,
-    INVALID_SIGNATURE,
-    INVALID_SENDER,
-    INVALID_TAKER,
-    INVALID_MAKER,
-    ORDER_INVALID_MAKER_ASSET_AMOUNT,
-    ORDER_INVALID_TAKER_ASSET_AMOUNT,
-    ORDER_FILLABLE,
-    ORDER_EXPIRED,
-    ORDER_FULLY_FILLED,
-    ORDER_CANCELLED,
+    INVALID_MAKER_ASSET_AMOUNT,
+    INVALID_TAKER_ASSET_AMOUNT,
+    FILLABLE,
+    EXPIRED,
+    FULLY_FILLED,
+    CANCELLED,
 }
 
 export enum ContractName {
diff --git a/packages/contracts/test/asset_proxy/authorizable.ts b/packages/contracts/test/asset_proxy/authorizable.ts
index 87f89c513..e8274acb1 100644
--- a/packages/contracts/test/asset_proxy/authorizable.ts
+++ b/packages/contracts/test/asset_proxy/authorizable.ts
@@ -19,6 +19,7 @@ describe('Authorizable', () => {
     let notOwner: string;
     let address: string;
     let authorizable: MixinAuthorizableContract;
+
     before(async () => {
         await blockchainLifecycle.startAsync();
     });
diff --git a/packages/contracts/test/exchange/core.ts b/packages/contracts/test/exchange/core.ts
index 8320e97d6..91ead93f0 100644
--- a/packages/contracts/test/exchange/core.ts
+++ b/packages/contracts/test/exchange/core.ts
@@ -15,7 +15,6 @@ import { ERC721ProxyContract } from '../../src/contract_wrappers/generated/e_r_c
 import {
     CancelContractEventArgs,
     ExchangeContract,
-    ExchangeStatusContractEventArgs,
     FillContractEventArgs,
 } from '../../src/contract_wrappers/generated/exchange';
 import { artifacts } from '../../src/utils/artifacts';
@@ -25,7 +24,8 @@ import { ERC20Wrapper } from '../../src/utils/erc20_wrapper';
 import { ERC721Wrapper } from '../../src/utils/erc721_wrapper';
 import { ExchangeWrapper } from '../../src/utils/exchange_wrapper';
 import { OrderFactory } from '../../src/utils/order_factory';
-import { ContractName, ERC20BalancesByOwner, ExchangeStatus } from '../../src/utils/types';
+import { orderUtils } from '../../src/utils/order_utils';
+import { ContractName, ERC20BalancesByOwner, OrderStatus } from '../../src/utils/types';
 import { provider, txDefaults, web3Wrapper } from '../../src/utils/web3_wrapper';
 
 chaiSetup.configure();
@@ -131,39 +131,6 @@ describe('Exchange core', () => {
             erc20Balances = await erc20Wrapper.getBalancesAsync();
             signedOrder = orderFactory.newSignedOrder();
         });
-
-        it('should create an unfillable order', async () => {
-            signedOrder = orderFactory.newSignedOrder({
-                makerAssetAmount: new BigNumber(1001),
-                takerAssetAmount: new BigNumber(3),
-            });
-
-            const takerAssetFilledAmountBefore = await exchangeWrapper.getTakerAssetFilledAmountAsync(
-                orderHashUtils.getOrderHashHex(signedOrder),
-            );
-            expect(takerAssetFilledAmountBefore).to.be.bignumber.equal(0);
-
-            const fillTakerAssetAmount1 = new BigNumber(2);
-            await exchangeWrapper.fillOrderAsync(signedOrder, takerAddress, {
-                takerAssetFillAmount: fillTakerAssetAmount1,
-            });
-
-            const takerAssetFilledAmountAfter1 = await exchangeWrapper.getTakerAssetFilledAmountAsync(
-                orderHashUtils.getOrderHashHex(signedOrder),
-            );
-            expect(takerAssetFilledAmountAfter1).to.be.bignumber.equal(fillTakerAssetAmount1);
-
-            const fillTakerAssetAmount2 = new BigNumber(1);
-            await exchangeWrapper.fillOrderAsync(signedOrder, takerAddress, {
-                takerAssetFillAmount: fillTakerAssetAmount2,
-            });
-
-            const takerAssetFilledAmountAfter2 = await exchangeWrapper.getTakerAssetFilledAmountAsync(
-                orderHashUtils.getOrderHashHex(signedOrder),
-            );
-            expect(takerAssetFilledAmountAfter2).to.be.bignumber.equal(takerAssetFilledAmountAfter1);
-        });
-
         it('should transfer the correct amounts when makerAssetAmount === takerAssetAmount', async () => {
             signedOrder = orderFactory.newSignedOrder({
                 makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 18),
@@ -550,37 +517,21 @@ describe('Exchange core', () => {
             );
         });
 
-        it('should not change erc20Balances if an order is expired', async () => {
-            signedOrder = orderFactory.newSignedOrder({
-                expirationTimeSeconds: new BigNumber(Math.floor((Date.now() - 10000) / 1000)),
-            });
-            await exchangeWrapper.fillOrderAsync(signedOrder, takerAddress);
-
-            const newBalances = await erc20Wrapper.getBalancesAsync();
-            expect(newBalances).to.be.deep.equal(erc20Balances);
-        });
-
-        it('should log an error event if an order is expired', async () => {
+        it('should throw if an order is expired', async () => {
             signedOrder = orderFactory.newSignedOrder({
                 expirationTimeSeconds: new BigNumber(Math.floor((Date.now() - 10000) / 1000)),
             });
-
-            const res = await exchangeWrapper.fillOrderAsync(signedOrder, takerAddress);
-            expect(res.logs).to.have.length(1);
-            const log = res.logs[0] as LogWithDecodedArgs<ExchangeStatusContractEventArgs>;
-            const statusCode = log.args.statusId;
-            expect(statusCode).to.be.equal(ExchangeStatus.ORDER_EXPIRED);
+            return expect(exchangeWrapper.fillOrderAsync(signedOrder, takerAddress)).to.be.rejectedWith(
+                constants.REVERT,
+            );
         });
 
-        it('should log an error event if no value is filled', async () => {
-            signedOrder = orderFactory.newSignedOrder({});
+        it('should throw if no value is filled', async () => {
+            signedOrder = orderFactory.newSignedOrder();
             await exchangeWrapper.fillOrderAsync(signedOrder, takerAddress);
-
-            const res = await exchangeWrapper.fillOrderAsync(signedOrder, takerAddress);
-            expect(res.logs).to.have.length(1);
-            const log = res.logs[0] as LogWithDecodedArgs<ExchangeStatusContractEventArgs>;
-            const statusCode = log.args.statusId;
-            expect(statusCode).to.be.equal(ExchangeStatus.ORDER_FULLY_FILLED);
+            return expect(exchangeWrapper.fillOrderAsync(signedOrder, takerAddress)).to.be.rejectedWith(
+                constants.REVERT,
+            );
         });
     });
 
@@ -618,12 +569,11 @@ describe('Exchange core', () => {
 
         it('should be able to cancel a full order', async () => {
             await exchangeWrapper.cancelOrderAsync(signedOrder, makerAddress);
-            await exchangeWrapper.fillOrderAsync(signedOrder, takerAddress, {
-                takerAssetFillAmount: signedOrder.takerAssetAmount.div(2),
-            });
-
-            const newBalances = await erc20Wrapper.getBalancesAsync();
-            expect(newBalances).to.be.deep.equal(erc20Balances);
+            return expect(
+                exchangeWrapper.fillOrderAsync(signedOrder, takerAddress, {
+                    takerAssetFillAmount: signedOrder.takerAssetAmount.div(2),
+                }),
+            ).to.be.rejectedWith(constants.REVERT);
         });
 
         it('should log 1 event with correct arguments', async () => {
@@ -641,26 +591,39 @@ describe('Exchange core', () => {
             expect(orderHashUtils.getOrderHashHex(signedOrder)).to.be.equal(logArgs.orderHash);
         });
 
-        it('should log an error if already cancelled', async () => {
+        it('should throw if already cancelled', async () => {
             await exchangeWrapper.cancelOrderAsync(signedOrder, makerAddress);
-
-            const res = await exchangeWrapper.cancelOrderAsync(signedOrder, makerAddress);
-            expect(res.logs).to.have.length(1);
-            const log = res.logs[0] as LogWithDecodedArgs<ExchangeStatusContractEventArgs>;
-            const statusCode = log.args.statusId;
-            expect(statusCode).to.be.equal(ExchangeStatus.ORDER_CANCELLED);
+            return expect(exchangeWrapper.cancelOrderAsync(signedOrder, makerAddress)).to.be.rejectedWith(
+                constants.REVERT,
+            );
         });
 
-        it('should log error if order is expired', async () => {
+        it('should throw if order is expired', async () => {
             signedOrder = orderFactory.newSignedOrder({
                 expirationTimeSeconds: new BigNumber(Math.floor((Date.now() - 10000) / 1000)),
             });
+            return expect(exchangeWrapper.cancelOrderAsync(signedOrder, makerAddress)).to.be.rejectedWith(
+                constants.REVERT,
+            );
+        });
+
+        it('should throw if rounding error is greater than 0.1%', async () => {
+            signedOrder = orderFactory.newSignedOrder({
+                makerAssetAmount: new BigNumber(1001),
+                takerAssetAmount: new BigNumber(3),
+            });
 
-            const res = await exchangeWrapper.cancelOrderAsync(signedOrder, makerAddress);
-            expect(res.logs).to.have.length(1);
-            const log = res.logs[0] as LogWithDecodedArgs<ExchangeStatusContractEventArgs>;
-            const statusCode = log.args.statusId;
-            expect(statusCode).to.be.equal(ExchangeStatus.ORDER_EXPIRED);
+            const fillTakerAssetAmount1 = new BigNumber(2);
+            await exchangeWrapper.fillOrderAsync(signedOrder, takerAddress, {
+                takerAssetFillAmount: fillTakerAssetAmount1,
+            });
+
+            const fillTakerAssetAmount2 = new BigNumber(1);
+            return expect(
+                exchangeWrapper.fillOrderAsync(signedOrder, takerAddress, {
+                    takerAssetFillAmount: fillTakerAssetAmount2,
+                }),
+            ).to.be.rejectedWith(constants.REVERT);
         });
     });
 
diff --git a/packages/contracts/test/exchange/match_orders.ts b/packages/contracts/test/exchange/match_orders.ts
index 07295d78a..24ee794bc 100644
--- a/packages/contracts/test/exchange/match_orders.ts
+++ b/packages/contracts/test/exchange/match_orders.ts
@@ -15,7 +15,6 @@ import { ERC721ProxyContract } from '../../src/contract_wrappers/generated/e_r_c
 import {
     CancelContractEventArgs,
     ExchangeContract,
-    ExchangeStatusContractEventArgs,
     FillContractEventArgs,
 } from '../../src/contract_wrappers/generated/exchange';
 import { artifacts } from '../../src/utils/artifacts';
@@ -30,8 +29,8 @@ import {
     ContractName,
     ERC20BalancesByOwner,
     ERC721TokenIdsByOwner,
-    ExchangeStatus,
     OrderInfo,
+    OrderStatus,
 } from '../../src/utils/types';
 import { provider, txDefaults, web3Wrapper } from '../../src/utils/web3_wrapper';
 
@@ -186,10 +185,10 @@ describe('matchOrders', () => {
             );
             // Verify left order was fully filled
             const leftOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderLeft);
-            expect(leftOrderInfo.orderStatus as ExchangeStatus).to.be.equal(ExchangeStatus.ORDER_FULLY_FILLED);
+            expect(leftOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
             // Verify right order was fully filled
             const rightOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderRight);
-            expect(rightOrderInfo.orderStatus as ExchangeStatus).to.be.equal(ExchangeStatus.ORDER_FULLY_FILLED);
+            expect(rightOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
         });
 
         it('should transfer the correct amounts when orders completely fill each other and taker doesnt take a profit', async () => {
@@ -227,10 +226,10 @@ describe('matchOrders', () => {
             );
             // Verify left order was fully filled
             const leftOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderLeft);
-            expect(leftOrderInfo.orderStatus as ExchangeStatus).to.be.equal(ExchangeStatus.ORDER_FULLY_FILLED);
+            expect(leftOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
             // Verify right order was fully filled
             const rightOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderRight);
-            expect(rightOrderInfo.orderStatus as ExchangeStatus).to.be.equal(ExchangeStatus.ORDER_FULLY_FILLED);
+            expect(rightOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
             // Verify taker did not take a profit
             expect(takerInitialBalances).to.be.deep.equal(
                 newERC20BalancesByOwner[takerAddress][defaultERC20MakerAssetAddress],
@@ -265,10 +264,10 @@ describe('matchOrders', () => {
             );
             // Verify left order was fully filled
             const leftOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderLeft);
-            expect(leftOrderInfo.orderStatus as ExchangeStatus).to.be.equal(ExchangeStatus.ORDER_FULLY_FILLED);
+            expect(leftOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
             // Verify right order was partially filled
             const rightOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderRight);
-            expect(rightOrderInfo.orderStatus as ExchangeStatus).to.be.equal(ExchangeStatus.ORDER_FILLABLE);
+            expect(rightOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FILLABLE);
         });
 
         it('should transfer the correct amounts when right order is completely filled and left order is partially filled', async () => {
@@ -299,10 +298,10 @@ describe('matchOrders', () => {
             );
             // Verify left order was partially filled
             const leftOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderLeft);
-            expect(leftOrderInfo.orderStatus as ExchangeStatus).to.be.equal(ExchangeStatus.ORDER_FILLABLE);
+            expect(leftOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FILLABLE);
             // Verify right order was fully filled
             const rightOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderRight);
-            expect(rightOrderInfo.orderStatus as ExchangeStatus).to.be.equal(ExchangeStatus.ORDER_FULLY_FILLED);
+            expect(rightOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
         });
 
         it('should transfer the correct amounts when consecutive calls are used to completely fill the left order', async () => {
@@ -338,10 +337,10 @@ describe('matchOrders', () => {
             );
             // Verify left order was partially filled
             const leftOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderLeft);
-            expect(leftOrderInfo.orderStatus as ExchangeStatus).to.be.equal(ExchangeStatus.ORDER_FILLABLE);
+            expect(leftOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FILLABLE);
             // Verify right order was fully filled
             const rightOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderRight);
-            expect(rightOrderInfo.orderStatus as ExchangeStatus).to.be.equal(ExchangeStatus.ORDER_FULLY_FILLED);
+            expect(rightOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
             // Construct second right order
             // Note: This order needs makerAssetAmount=90/takerAssetAmount=[anything <= 45] to fully fill the right order.
             //       However, we use 100/50 to ensure a partial fill as we want to go down the "left fill"
@@ -368,10 +367,10 @@ describe('matchOrders', () => {
             );
             // Verify left order was fully filled
             const leftOrderInfo2: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderLeft);
-            expect(leftOrderInfo2.orderStatus as ExchangeStatus).to.be.equal(ExchangeStatus.ORDER_FULLY_FILLED);
+            expect(leftOrderInfo2.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
             // Verify second right order was partially filled
             const rightOrderInfo2: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderRight2);
-            expect(rightOrderInfo2.orderStatus as ExchangeStatus).to.be.equal(ExchangeStatus.ORDER_FILLABLE);
+            expect(rightOrderInfo2.orderStatus as OrderStatus).to.be.equal(OrderStatus.FILLABLE);
         });
 
         it('should transfer the correct amounts when consecutive calls are used to completely fill the right order', async () => {
@@ -408,10 +407,10 @@ describe('matchOrders', () => {
             );
             // Verify left order was partially filled
             const leftOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderLeft);
-            expect(leftOrderInfo.orderStatus as ExchangeStatus).to.be.equal(ExchangeStatus.ORDER_FULLY_FILLED);
+            expect(leftOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
             // Verify right order was fully filled
             const rightOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderRight);
-            expect(rightOrderInfo.orderStatus as ExchangeStatus).to.be.equal(ExchangeStatus.ORDER_FILLABLE);
+            expect(rightOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FILLABLE);
             // Create second left order
             // Note: This order needs makerAssetAmount=96/takerAssetAmount=48 to fully fill the right order.
             //       However, we use 100/50 to ensure a partial fill as we want to go down the "right fill"
@@ -441,10 +440,10 @@ describe('matchOrders', () => {
             );
             // Verify second left order was partially filled
             const leftOrderInfo2: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderLeft2);
-            expect(leftOrderInfo2.orderStatus as ExchangeStatus).to.be.equal(ExchangeStatus.ORDER_FILLABLE);
+            expect(leftOrderInfo2.orderStatus as OrderStatus).to.be.equal(OrderStatus.FILLABLE);
             // Verify right order was fully filled
             const rightOrderInfo2: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderRight);
-            expect(rightOrderInfo2.orderStatus as ExchangeStatus).to.be.equal(ExchangeStatus.ORDER_FULLY_FILLED);
+            expect(rightOrderInfo2.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
         });
 
         it('should transfer the correct amounts if fee recipient is the same across both matched orders', async () => {
@@ -790,10 +789,10 @@ describe('matchOrders', () => {
             );
             // Verify left order was fully filled
             const leftOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderLeft);
-            expect(leftOrderInfo.orderStatus as ExchangeStatus).to.be.equal(ExchangeStatus.ORDER_FULLY_FILLED);
+            expect(leftOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
             // Verify right order was fully filled
             const rightOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderRight);
-            expect(rightOrderInfo.orderStatus as ExchangeStatus).to.be.equal(ExchangeStatus.ORDER_FULLY_FILLED);
+            expect(rightOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
         });
 
         it('should transfer correct amounts when right order maker asset is an ERC721 token', async () => {
@@ -825,10 +824,10 @@ describe('matchOrders', () => {
             );
             // Verify left order was fully filled
             const leftOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderLeft);
-            expect(leftOrderInfo.orderStatus as ExchangeStatus).to.be.equal(ExchangeStatus.ORDER_FULLY_FILLED);
+            expect(leftOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
             // Verify right order was fully filled
             const rightOrderInfo: OrderInfo = await exchangeWrapper.getOrderInfoAsync(signedOrderRight);
-            expect(rightOrderInfo.orderStatus as ExchangeStatus).to.be.equal(ExchangeStatus.ORDER_FULLY_FILLED);
+            expect(rightOrderInfo.orderStatus as OrderStatus).to.be.equal(OrderStatus.FULLY_FILLED);
         });
     });
 }); // tslint:disable-line:max-file-line-count
diff --git a/packages/contracts/test/exchange/transactions.ts b/packages/contracts/test/exchange/transactions.ts
index 9af8b522b..f31053ad3 100644
--- a/packages/contracts/test/exchange/transactions.ts
+++ b/packages/contracts/test/exchange/transactions.ts
@@ -18,7 +18,7 @@ import { ExchangeWrapper } from '../../src/utils/exchange_wrapper';
 import { OrderFactory } from '../../src/utils/order_factory';
 import { orderUtils } from '../../src/utils/order_utils';
 import { TransactionFactory } from '../../src/utils/transaction_factory';
-import { ERC20BalancesByOwner, ExchangeStatus, SignedTransaction } from '../../src/utils/types';
+import { ERC20BalancesByOwner, OrderStatus, SignedTransaction } from '../../src/utils/types';
 import { provider, txDefaults, web3Wrapper } from '../../src/utils/web3_wrapper';
 
 chaiSetup.configure();
@@ -194,9 +194,9 @@ describe('Exchange transactions', () => {
 
             it('should cancel the order when signed by maker and called by sender', async () => {
                 await exchangeWrapper.executeTransactionAsync(signedTx, senderAddress);
-                const res = await exchangeWrapper.fillOrderAsync(signedOrder, senderAddress);
-                const newBalances = await erc20Wrapper.getBalancesAsync();
-                expect(newBalances).to.deep.equal(erc20Balances);
+                return expect(exchangeWrapper.fillOrderAsync(signedOrder, senderAddress)).to.be.rejectedWith(
+                    constants.REVERT,
+                );
             });
         });
     });
diff --git a/packages/contracts/test/exchange/wrapper.ts b/packages/contracts/test/exchange/wrapper.ts
index a158ba8f3..583ec9f91 100644
--- a/packages/contracts/test/exchange/wrapper.ts
+++ b/packages/contracts/test/exchange/wrapper.ts
@@ -959,7 +959,7 @@ describe('Exchange wrappers', () => {
                 const takerAssetCancelAmounts = _.map(signedOrders, signedOrder => signedOrder.takerAssetAmount);
                 await exchangeWrapper.batchCancelOrdersAsync(signedOrders, makerAddress);
 
-                await exchangeWrapper.batchFillOrdersAsync(signedOrders, takerAddress, {
+                await exchangeWrapper.batchFillOrdersNoThrowAsync(signedOrders, takerAddress, {
                     takerAssetFillAmounts: takerAssetCancelAmounts,
                 });
                 const newBalances = await erc20Wrapper.getBalancesAsync();