Ran prettier/linter

contracts/exchange/contracts/src/MixinAssetProxyDispatcher.sol

@@ -179,13 +179,16 @@ contract MixinAssetProxyDispatcher is
                 )
 
                 if iszero(didSucceed) { // Call reverted.
-                    // Get the revert data.
                     let revertDataSize := returndatasize()
+                    // Construct a `bytes memory` type to hold the revert data
+                    // at `cdStart`.
+                    // The first 32 bytes are the length of the data.
+                    mstore(cdStart, revertDataSize)
+                    // Copy the revert data immediately after the length. 
+                    returndatacopy(add(cdStart, 32), 0, revertDataSize)
                     // We need to move the free memory pointer because we
                     // still have solidity logic that executes after this assembly.
-                    mstore(64, add(cdStart, revertDataSize))
+                    mstore(64, add(cdStart, add(revertDataSize, 32)))
-                    // Copy the revert data.
-                    returndatacopy(cdStart, 0, revertDataSize)
                     revertData := cdStart
                 }
             }

contracts/exchange/contracts/test/TestRevertReceiver.sol

@@ -21,9 +21,10 @@ pragma solidity ^0.5.5;
 import "@0x/contracts-erc20/contracts/src/interfaces/IERC20Token.sol";
 
 
+// solhint-disable no-unused-vars
 contract TestRevertReceiver {
 
-    string constant REVERT_REASON = "you shall not pass";
+    string constant public REVERT_REASON = "you shall not pass";
 
     /// @dev Reverts with `REVERT_REASON`. Intended to be used with `Validator` signature type.
     /// @param hash Message hash that is signed.

contracts/exchange/test/signature_validator.ts

@@ -90,13 +90,9 @@ describe('MixinSignatureValidator', () => {
         );
         signatureValidatorLogDecoder = new LogDecoder(web3Wrapper, artifacts);
         await web3Wrapper.awaitTransactionSuccessAsync(
-            await signatureValidator.setSignatureValidatorApproval.sendTransactionAsync(
+            await signatureValidator.setSignatureValidatorApproval.sendTransactionAsync(testValidator.address, true, {
-                testValidator.address,
+                from: signerAddress,
-                true,
+            }),
-                {
-                    from: signerAddress,
-                },
-            ),
             constants.AWAIT_TRANSACTION_MINED_MS,
         );
         await web3Wrapper.awaitTransactionSuccessAsync(
@@ -144,6 +140,8 @@ describe('MixinSignatureValidator', () => {
     });
 
     describe('isValidSignature', () => {
+        const REVERT_REASON = 'you shall not pass';
+
         beforeEach(async () => {
             signedOrder = await orderFactory.newSignedOrderAsync();
         });
@@ -412,7 +410,7 @@ describe('MixinSignatureValidator', () => {
                 orderHashHex,
                 revertingWallet.address,
                 signatureHex,
-                new StringRevertError('you shall not pass').encode(),
+                new StringRevertError(REVERT_REASON).encode(),
             );
             const tx = signatureValidator.publicIsValidSignature.callAsync(
                 orderHashHex,
@@ -464,11 +462,7 @@ describe('MixinSignatureValidator', () => {
                 signatureHex,
                 constants.NULL_BYTES,
             );
-            const tx = signatureValidator.publicIsValidSignature.callAsync(
+            const tx = signatureValidator.publicIsValidSignature.callAsync(orderHashHex, signerAddress, signatureHex);
-                orderHashHex,
-                signerAddress,
-                signatureHex,
-            );
             return expect(tx).to.revertWith(expectedError);
         });
 
@@ -482,13 +476,9 @@ describe('MixinSignatureValidator', () => {
                 orderHashHex,
                 signedOrder.makerAddress,
                 signatureHex,
-                new StringRevertError('you shall not pass').encode(),
+                new StringRevertError(REVERT_REASON).encode(),
-            );
-            const tx = signatureValidator.publicIsValidSignature.callAsync(
-                orderHashHex,
-                signerAddress,
-                signatureHex,
             );
+            const tx = signatureValidator.publicIsValidSignature.callAsync(orderHashHex, signerAddress, signatureHex);
             return expect(tx).to.revertWith(expectedError);
         });