Add missing checks and return values (#535)

contracts/upgradeable_contracts/BaseMediatorFeeManager.sol

@@ -2,6 +2,7 @@ pragma solidity 0.4.24;
 
 import "openzeppelin-solidity/contracts/ownership/Ownable.sol";
 import "openzeppelin-solidity/contracts/math/SafeMath.sol";
+import "openzeppelin-solidity/contracts/AddressUtils.sol";
 
 /**
 * @title BaseMediatorFeeManager
@@ -32,8 +33,10 @@ contract BaseMediatorFeeManager is Ownable {
     * @param _owner address of the owner of the fee manager contract.
     * @param _fee the fee percentage amount.
     * @param _rewardAccountList list of addresses that will receive the fee rewards.
+    * @param _mediatorContract address of the mediator contract used together with this fee manager.
     */
     constructor(address _owner, uint256 _fee, address[] _rewardAccountList, address _mediatorContract) public {
+        require(AddressUtils.isContract(_mediatorContract));
         require(_rewardAccountList.length > 0 && _rewardAccountList.length <= MAX_REWARD_ACCOUNTS);
         _transferOwnership(_owner);
         _setFee(_fee);

contracts/upgradeable_contracts/InterestReceiver.sol

@@ -29,6 +29,7 @@ contract InterestReceiver is ERC677Receiver, Ownable, Claimable, TokenSwapper {
     */
     constructor(address _owner, address _bridgeContract, address _receiverInXDai) public {
         require(AddressUtils.isContract(_bridgeContract));
+        require(_receiverInXDai != address(0));
         _transferOwnership(_owner);
         bridgeContract = _bridgeContract;
         receiverInXDai = _receiverInXDai;
@@ -49,6 +50,7 @@ contract InterestReceiver is ERC677Receiver, Ownable, Claimable, TokenSwapper {
     * @param _receiverInXDai address of new receiver account in the xDai chain
     */
     function setReceiverInXDai(address _receiverInXDai) external onlyOwner {
+        require(_receiverInXDai != address(0));
         receiverInXDai = _receiverInXDai;
     }
 
@@ -93,6 +95,7 @@ contract InterestReceiver is ERC677Receiver, Ownable, Claimable, TokenSwapper {
             daiToken().approve(address(bridgeContract), 0);
             emit RelayTokensFailed(receiverInXDai, finalDaiBalance);
         }
+        return true;
     }
 
     /**

contracts/upgradeable_contracts/multi_amb_erc20_to_erc677/HomeMultiAMBErc20ToErc677.sol

@@ -98,6 +98,7 @@ contract HomeMultiAMBErc20ToErc677 is BasicMultiAMBErc20ToErc677, HomeFeeManager
     ) external onlyMediator {
         string memory name = _name;
         string memory symbol = _symbol;
+        require(bytes(name).length > 0 || bytes(symbol).length > 0);
         if (bytes(name).length == 0) {
             name = symbol;
         } else if (bytes(symbol).length == 0) {

test/amb_native_to_erc20/foreign_mediator.test.js

@@ -601,6 +601,15 @@ contract('ForeignAMBNativeToErc20', async accounts => {
             mediator.address,
             token.address
           ).should.be.rejectedWith(ERROR_MSG)
+          // invalid mediator contract address
+          await ForeignFeeManagerAMBNativeToErc20.new(
+            owner,
+            fee,
+            rewardAccountList,
+            ZERO_ADDRESS,
+            token.address
+          ).should.be.rejectedWith(ERROR_MSG)
+          // invalid token address
           await ForeignFeeManagerAMBNativeToErc20.new(
             owner,
             fee,

test/amb_native_to_erc20/home_mediator.test.js

@@ -1120,6 +1120,10 @@ contract('HomeAMBNativeToErc20', async accounts => {
             [...rewardAccountList, mediator.address],
             mediator.address
           ).should.be.rejectedWith(ERROR_MSG)
+          // invalid mediator contract
+          await HomeFeeManagerAMBNativeToErc20.new(owner, fee, rewardAccountList, ZERO_ADDRESS).should.be.rejectedWith(
+            ERROR_MSG
+          )
           await HomeFeeManagerAMBNativeToErc20.new(owner, fee, rewardAccountList, mediator.address)
         })
       })

test/erc_to_native/foreign_bridge.test.js

@@ -1598,6 +1598,7 @@ contract('ForeignBridge_ERC20_to_Native', async accounts => {
         })
 
         it('should update bridge contract address', async () => {
+          await interestRecipient.setReceiverInXDai(ZERO_ADDRESS, { from: receiverOwner }).should.be.rejected
           await interestRecipient.setReceiverInXDai(accounts[8], { from: receiverOwner }).should.be.fulfilled
           expect(await interestRecipient.receiverInXDai()).to.be.equal(accounts[8])
         })

test/multi_amb_erc20_to_erc677/home_mediator.test.js

@@ -419,6 +419,34 @@ contract('HomeMultiAMBErc20ToErc677', async accounts => {
         expect(await homeToken.decimals()).to.be.bignumber.equal('18')
       })
 
+      it('should not register new token with empty name and empty symbol', async () => {
+        const data1 = await contract.contract.methods
+          .deployAndHandleBridgedTokens(accounts[0], '', '', 18, user, oneEther.toString(10))
+          .encodeABI()
+        await ambBridgeContract.executeMessageCall(
+          contract.address,
+          otherSideMediator.address,
+          data1,
+          exampleMessageId,
+          2000000
+        ).should.be.fulfilled
+
+        expect(await ambBridgeContract.messageCallStatus(exampleMessageId)).to.be.equal(false)
+
+        const data2 = await contract.contract.methods
+          .deployAndHandleBridgedTokens(accounts[1], 'TEST', '', 18, user, oneEther.toString(10))
+          .encodeABI()
+        await ambBridgeContract.executeMessageCall(
+          contract.address,
+          otherSideMediator.address,
+          data2,
+          otherMessageId,
+          2000000
+        ).should.be.fulfilled
+
+        expect(await ambBridgeContract.messageCallStatus(otherMessageId)).to.be.equal(true)
+      })
+
       for (const decimals of [3, 18, 20]) {
         it(`should initialize limits according to decimals = ${decimals}`, async () => {
           const f1 = toBN(`1${'0'.repeat(decimals)}`)