Reward calculation clean up for zero gas.

contracts/gateway/EIP20CoGateway.sol

@@ -741,6 +741,7 @@ contract EIP20CoGateway is GatewayBase {
         );
     }
 
+
     /* Public functions */
 
     /**
@@ -979,6 +980,7 @@ contract EIP20CoGateway is GatewayBase {
         );
     }
 
+
     /* Private functions */
 
     /**
@@ -1063,12 +1065,12 @@ contract EIP20CoGateway is GatewayBase {
      * @notice This is internal method for process minting contains common logic.
      *
      * @param _messageHash Message hash.
-     * @param _initialGas initial gas during progress process.
+     * @param _initialGas Initial gas during progress process.
      *
-     * @param _proofProgress true if progress with proof, false if progress
+     * @param _proofProgress True if progress with proof, false if progress
      *                       with hashlock.
-     * @param _unlockSecret unlock secret to progress, zero in case of progress
-     *                      with proof
+     * @param _unlockSecret Unlock secret to progress, zero in case of progress
+     *                      with proof.
      *
      * @return  beneficiary_ Address to which the utility tokens will be
      *                      transferred after minting.
@@ -1077,9 +1079,8 @@ contract EIP20CoGateway is GatewayBase {
      *                      is given to the facilitator.
      * @return mintedAmount_ Actual minted amount, after deducting the reward
      *                        from the total amount.
-     * @return rewardAmount_ Reward amount that is transferred to facilitator
+     * @return rewardAmount_ Reward amount that is transferred to facilitator.
      */
-
     function progressMintInternal(
         bytes32 _messageHash,
         uint256 _initialGas,
@@ -1111,16 +1112,18 @@ contract EIP20CoGateway is GatewayBase {
 
         mintedAmount_ = stakeAmount_.sub(rewardAmount_);
 
-        //Mint token after subtracting reward amount
+        // Mint token after subtracting reward amount.
         UtilityTokenInterface(utilityToken).mint(beneficiary_, mintedAmount_);
 
-        //reward beneficiary with the reward amount
-        UtilityTokenInterface(utilityToken).mint(msg.sender, rewardAmount_);
+        if(rewardAmount_ > 0) {
+            // Reward beneficiary with the reward amount.
+            UtilityTokenInterface(utilityToken).mint(msg.sender, rewardAmount_);
+        }
 
-        // delete the mint data
+        // Delete the mint data.
         delete mints[_messageHash];
 
-        // Emit MintProgressed event
+        // Emit MintProgressed event.
         emit MintProgressed(
             _messageHash,
             message.sender,

contracts/gateway/EIP20Gateway.sol

@@ -897,6 +897,9 @@ contract EIP20Gateway is GatewayBase {
         progressUnstakeInternal(_messageHash, initialGas, bytes32(0), true);
     }
 
+
+    /** External methods */
+
     /**
      * @notice Declare redeem revert intent.
      *         This will set message status to revoked. This method will also

contracts/test/MockUtilityToken.sol

@@ -0,0 +1,61 @@
+pragma solidity ^0.5.0;
+
+// Copyright 2017 OpenST Ltd.
+//
+// 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.
+//
+// ----------------------------------------------------------------------------
+// Auxiliary chain: MockUtilityToken
+//
+// http://www.simpletoken.org/
+//
+// ----------------------------------------------------------------------------
+
+contract MockUtilityToken {
+
+    /* Storage */
+
+    /**
+     * Address to which the utility tokens will be transferred after minting.
+     */
+    address public beneficiary;
+
+    /* Amount received by beneficiary.  */
+    uint256 public amount;
+
+
+    /* External functions */
+
+    /**
+     * @notice Mints the utility token
+     *
+     * @dev Adds _amount tokens to beneficiary balance and increases the
+     *      totalTokenSupply. Can be called only by CoGateway.
+     *
+     * @param _beneficiary Address of tokens beneficiary.
+     * @param _amount Amount of tokens to mint.
+     *
+     * @return True if mint is successful, false otherwise.
+     */
+    function mint(
+        address _beneficiary,
+        uint256 _amount
+    )
+        external
+        returns (bool /* success */)
+    {
+        beneficiary = _beneficiary;
+        amount = _amount;
+        return true;
+    }
+}

contracts/test/TestEIP20CoGateway.sol

@@ -0,0 +1,138 @@
+pragma solidity ^0.5.0;
+
+import "../gateway/EIP20CoGateway.sol";
+
+/**
+ * @title TestEIP20CoGateway contract.
+ *
+ * @notice Used for test only.
+ */
+contract TestEIP20CoGateway is EIP20CoGateway {
+
+    /* Constructor */
+
+    /**
+     * @notice Initialise the contract by providing the Gateway contract
+     *         address for which the CoGateway will enable facilitation of
+     *         minting and redeeming.
+     *
+     * @param _valueToken The value token contract address.
+     * @param _utilityToken The utility token address that will be used for
+     *                      minting the utility token.
+     * @param _core Core contract address.
+     * @param _bounty The amount that facilitator will stakes to initiate the
+     *                staking process.
+     * @param _membersManager Organisation address.
+     * @param _gateway Gateway contract address.
+     */
+    constructor(
+        address _valueToken,
+        address _utilityToken,
+        CoreInterface _core,
+        uint256 _bounty,
+        IsMemberInterface _membersManager,
+        address _gateway
+    )
+    EIP20CoGateway(
+        _valueToken,
+        _utilityToken,
+        _core,
+        _bounty,
+        _membersManager,
+        _gateway
+    )
+    public
+    {
+
+    }
+
+
+    /* Public Functions */
+
+    /**
+     * @notice It is used to set the messagehash.
+     *
+     * @dev It is for test purposes only.
+     *
+     * @param _intentHash Intent hash.
+     * @param _stakerNonce Nonce of the staker address.
+     * @param _gasPrice Gas price that staker is ready to pay to get the stake
+     *                  and mint process done.
+     * @param _gasLimit Gas limit that staker is ready to pay.
+     * @param _hashLock Hash Lock provided by the facilitator.
+     * @param _staker Staker address.
+     *
+     * @return messageHash_ Hash unique for every request.
+     */
+    function setMessage(
+        bytes32 _intentHash,
+        uint256 _stakerNonce,
+        uint256 _gasPrice,
+        uint256 _gasLimit,
+        bytes32 _hashLock,
+        address _staker
+    )
+        public
+        returns (bytes32 messageHash_)
+    {
+
+        messageHash_ = MessageBus.messageDigest(
+            STAKE_TYPEHASH,
+            _intentHash,
+            _stakerNonce,
+            _gasPrice,
+            _gasLimit
+        );
+
+        messages[messageHash_] = getMessage(
+            _staker,
+            _stakerNonce,
+            _gasPrice,
+            _gasLimit,
+            _intentHash,
+            _hashLock
+        );
+
+        return messageHash_;
+
+    }
+
+    /**
+     * @notice It sets the mints mapping with respect to the messageHash.
+     *
+     * @dev It is for test purposes only.
+     *
+     * @param _messageHash Hash for which mints mapping is updated.
+     * @param _beneficiary Beneficiary  Address to which the utility tokens
+     *                     will be transferred after minting.
+     * @param _amount Total amount for which the stake was initiated. The
+     *                reward amount is deducted from the total amount and
+     *                is given to the facilitator.
+     */
+    function setMints(
+        bytes32 _messageHash,
+        address _beneficiary,
+        uint256 _amount
+    )
+        public
+    {
+        mints[_messageHash] = Mint({
+            amount : _amount,
+            beneficiary : _beneficiary
+        });
+    }
+
+    /**
+     * @notice It sets the status of inbox to Declared.
+     *
+     * @dev It is for test purposes only.
+     *
+     * @param _messageHash Hash for which status is set to Declared.
+     */
+    function setInboxStatus(bytes32 _messageHash) public {
+
+        messageBox.inbox[_messageHash] = MessageBus.MessageStatus.Declared;
+
+    }
+
+}

migrations/2_deploy_contracts.js

@@ -8,6 +8,7 @@ const MetaBlock = artifacts.require("../contracts/lib/MetaBlock.sol");
 const BlockStore = artifacts.require("../contracts/BlockStore.sol");
 const TestEIP20Gateway = artifacts.require("TestEIP20Gateway");
 const EIP20CoGateway = artifacts.require("EIP20CoGateway");
+const TestEIP20CoGateway = artifacts.require("TestEIP20CoGateway");
 const AuxiliaryBlockStore = artifacts.require(
     "../contracts/AuxiliaryBlockStore.sol"
 );
@@ -35,8 +36,8 @@ module.exports = function (deployer) {
     deployer.deploy(GatewayLib);
     deployer.deploy(MockGatewayLib);
     deployer.deploy(MetaBlock);
-    deployer.link(GatewayLib, [GatewayBase, EIP20Gateway, TestEIP20Gateway, EIP20CoGateway]);
-    deployer.link(MessageBus, [EIP20CoGateway,TestEIP20Gateway, EIP20Gateway]);
+    deployer.link(GatewayLib, [GatewayBase, EIP20Gateway, TestEIP20Gateway, EIP20CoGateway, TestEIP20CoGateway]);
+    deployer.link(MessageBus, [EIP20CoGateway, TestEIP20CoGateway, TestEIP20Gateway, EIP20Gateway]);
     deployer.link(MockGatewayLib, [MockGatewayBase, TestEIP20Gateway]);
     deployer.link(MetaBlock, [BlockStore, AuxiliaryBlockStore]);