address PR comments

src/child/ChildERC20Bridge.sol

@@ -68,9 +68,8 @@ contract ChildERC20Bridge is
      * @notice Fallback function on recieving native IMX from WIMX contract.
      */
     receive() external payable {
-        // Revert if sender if not the wIMX token address
-        // Or the wIMXToken is not set (contract not initialized)
-        if (msg.sender != wIMXToken || wIMXToken == address(0)) {
+        // Revert if sender is not the WIMX token address
+        if (msg.sender != wIMXToken) {
             revert NonWrappedNativeTransfer();
         }
     }
@@ -245,7 +244,7 @@ contract ChildERC20Bridge is
             revert ZeroAmount();
         }
         if (msg.value == 0) {
-            revert ZeroValue();
+            revert NoGas();
         }
 
         address rootToken;
@@ -385,7 +384,7 @@ contract ChildERC20Bridge is
             if (rootToken == NATIVE_ETH) {
                 childToken = childETHToken;
             } else {
-                childToken = IChildERC20(rootTokenToChildToken[address(rootToken)]);
+                childToken = IChildERC20(rootTokenToChildToken[rootToken]);
                 if (address(childToken) == address(0)) {
                     revert NotMapped();
                 }

src/interfaces/child/IChildERC20Bridge.sol

@@ -118,8 +118,8 @@ interface IChildERC20BridgeErrors {
     error InsufficientValue();
     /// @notice Error when the withdrawal amount is zero
     error ZeroAmount();
-    /// @notice Error when the msg.value amount is zero
-    error ZeroValue();
+    /// @notice Error when a message is sent with no gas payment.
+    error NoGas();
     /// @notice Error when the contract to mint had no bytecode.
     error EmptyTokenContract();
     /// @notice Error when the mint operation failed.

src/interfaces/root/IRootERC20Bridge.sol

@@ -97,6 +97,8 @@ interface IRootERC20BridgeErrors {
     error ZeroAmount();
     /// @notice Error when a zero address is given when not valid.
     error ZeroAddress();
+    /// @notice Error when a message is sent with no gas payment.
+    error NoGas();
     /// @notice Error when the child chain name is invalid.
     error InvalidChildChain();
     /// @notice Error when a token is already mapped.

src/root/RootERC20Bridge.sol

@@ -170,8 +170,7 @@ contract RootERC20Bridge is
      */
     receive() external payable {
         // Revert if sender is not the WETH token address
-        // Or the rootWETHToken is not set (contract not initialized)
-        if (msg.sender != rootWETHToken || rootWETHToken == address(0)) {
+        if (msg.sender != rootWETHToken) {
             revert NonWrappedNativeTransfer();
         }
     }
@@ -289,6 +288,9 @@ contract RootERC20Bridge is
     }
 
     function _mapToken(IERC20Metadata rootToken) private returns (address) {
+        if (msg.value == 0) {
+            revert NoGas();
+        }
         if (address(rootToken) == address(0)) {
             revert ZeroAddress();
         }
@@ -331,6 +333,9 @@ contract RootERC20Bridge is
         if (amount == 0) {
             revert ZeroAmount();
         }
+        if (msg.value == 0) {
+            revert NoGas();
+        }
         if (
             address(rootToken) == rootIMXToken && imxCumulativeDepositLimit != UNLIMITED_DEPOSIT
                 && IERC20Metadata(rootIMXToken).balanceOf(address(this)) + amount > imxCumulativeDepositLimit

test/integration/child/withdrawals/ChildAxelarBridgeWithdraw.t.sol

@@ -20,9 +20,6 @@ contract ChildERC20BridgeWithdrawIntegrationTest is
     IChildAxelarBridgeAdaptorErrors,
     Utils
 {
-    // Define here to avoid error collisions between IChildERC20BridgeErrors and IChildAxelarBridgeAdaptorErrors
-    error ZeroValue();
-
     address constant CHILD_BRIDGE = address(3);
     address constant CHILD_BRIDGE_ADAPTOR = address(4);
     string constant CHILD_CHAIN_NAME = "test";
@@ -134,7 +131,7 @@ contract ChildERC20BridgeWithdrawIntegrationTest is
     function test_RevertIf_WithdrawWithNoGas() public {
         ChildERC20 childToken = ChildERC20(childBridge.rootTokenToChildToken(rootToken));
 
-        vm.expectRevert(ZeroValue.selector);
+        vm.expectRevert(NoGas.selector);
         childBridge.withdraw(childToken, withdrawAmount);
     }
 }

test/integration/child/withdrawals/ChildAxelarBridgeWithdrawWIMX.t.sol

@@ -22,16 +22,10 @@ contract ChildERC20BridgeWithdrawWIMXIntegrationTest is
     IChildAxelarBridgeAdaptorErrors,
     Utils
 {
-    // TODO: consider moving this to a setup function
-    address constant CHILD_BRIDGE = address(3);
     address constant ROOT_IMX_TOKEN = address(555555);
     address constant WRAPPED_IMX = address(0xabc);
-
     ChildERC20Bridge public childBridge;
     ChildAxelarBridgeAdaptor public axelarAdaptor;
-    address public rootToken;
-    address public rootImxToken;
-    ChildERC20 public childTokenTemplate;
     MockAxelarGasService public mockAxelarGasService;
     MockAxelarGateway public mockAxelarGateway;
     WIMX public wIMXToken;

test/integration/child/withdrawals/ChildAxelarBridgeWithdrawWIMXTo.t.sol

@@ -26,7 +26,6 @@ contract ChildERC20BridgeWithdrawWIMXToIntegrationTest is
     IChildAxelarBridgeAdaptorErrors,
     Utils
 {
-    address constant CHILD_BRIDGE = address(3);
     address constant ROOT_IMX_TOKEN = address(555555);
     address constant WRAPPED_IMX = address(0xabc);
 
@@ -47,19 +46,20 @@ contract ChildERC20BridgeWithdrawWIMXToIntegrationTest is
     }
 
     function test_WithdrawWIMXTo_CallsBridgeAdaptor() public {
+        address receiver = address(0xabcd);
         uint256 withdrawFee = 1;
         uint256 withdrawAmount = 7 ether;
 
         wIMXToken.approve(address(childBridge), withdrawAmount);
         bytes memory predictedPayload =
-            abi.encode(WITHDRAW_SIG, ROOT_IMX_TOKEN, address(this), address(this), withdrawAmount);
+            abi.encode(WITHDRAW_SIG, ROOT_IMX_TOKEN, address(this), receiver, withdrawAmount);
         vm.expectCall(
             address(axelarAdaptor),
             withdrawFee,
             abi.encodeWithSelector(axelarAdaptor.sendMessage.selector, predictedPayload, address(this))
         );
 
-        childBridge.withdrawWIMXTo{value: withdrawFee}(address(this), withdrawAmount);
+        childBridge.withdrawWIMXTo{value: withdrawFee}(receiver, withdrawAmount);
     }
 
     function test_WithdrawWIMXToWithDifferentAccount_CallsBridgeAdaptor() public {
@@ -80,12 +80,13 @@ contract ChildERC20BridgeWithdrawWIMXToIntegrationTest is
     }
 
     function test_WithdrawWIMXTo_CallsAxelarGateway() public {
+        address reciever = address(0xabcd);
         uint256 withdrawFee = 300;
         uint256 withdrawAmount = 7 ether;
 
         wIMXToken.approve(address(childBridge), withdrawAmount);
         bytes memory predictedPayload =
-            abi.encode(WITHDRAW_SIG, ROOT_IMX_TOKEN, address(this), address(this), withdrawAmount);
+            abi.encode(WITHDRAW_SIG, ROOT_IMX_TOKEN, address(this), reciever, withdrawAmount);
         vm.expectCall(
             address(mockAxelarGateway),
             0,
@@ -97,11 +98,11 @@ contract ChildERC20BridgeWithdrawWIMXToIntegrationTest is
             )
         );
 
-        childBridge.withdrawWIMXTo{value: withdrawFee}(address(this), withdrawAmount);
+        childBridge.withdrawWIMXTo{value: withdrawFee}(reciever, withdrawAmount);
     }
 
     function test_WithdrawWIMXToWithDifferentAccount_CallsAxelarGateway() public {
-        address receiver = address(0xabcde);
+        address receiver = address(0xabcd);
         uint256 withdrawFee = 300;
         uint256 withdrawAmount = 7 ether;
 
@@ -123,12 +124,13 @@ contract ChildERC20BridgeWithdrawWIMXToIntegrationTest is
     }
 
     function test_WithdrawWIMXTo_CallsGasService() public {
+        address receiver = address(0xabcd);
         uint256 withdrawFee = 300;
         uint256 withdrawAmount = 7 ether;
 
         wIMXToken.approve(address(childBridge), withdrawAmount);
         bytes memory predictedPayload =
-            abi.encode(WITHDRAW_SIG, ROOT_IMX_TOKEN, address(this), address(this), withdrawAmount);
+            abi.encode(WITHDRAW_SIG, ROOT_IMX_TOKEN, address(this), receiver, withdrawAmount);
 
         vm.expectCall(
             address(axelarGasService),
@@ -143,7 +145,7 @@ contract ChildERC20BridgeWithdrawWIMXToIntegrationTest is
             )
         );
 
-        childBridge.withdrawWIMXTo{value: withdrawFee}(address(this), withdrawAmount);
+        childBridge.withdrawWIMXTo{value: withdrawFee}(receiver, withdrawAmount);
     }
 
     function test_WithdrawWIMXToWithDifferentAccount_CallsGasService() public {
@@ -172,17 +174,18 @@ contract ChildERC20BridgeWithdrawWIMXToIntegrationTest is
     }
 
     function test_WithdrawWIMXTo_EmitsAxelarMessageSentEvent() public {
+        address receiver = address(0xabcd);
         uint256 withdrawFee = 300;
         uint256 withdrawAmount = 7 ether;
 
         wIMXToken.approve(address(childBridge), withdrawAmount);
         bytes memory predictedPayload =
-            abi.encode(WITHDRAW_SIG, ROOT_IMX_TOKEN, address(this), address(this), withdrawAmount);
+            abi.encode(WITHDRAW_SIG, ROOT_IMX_TOKEN, address(this), receiver, withdrawAmount);
 
         vm.expectEmit(address(axelarAdaptor));
         emit AxelarMessageSent(childBridge.rootChain(), childBridge.rootERC20BridgeAdaptor(), predictedPayload);
 
-        childBridge.withdrawWIMXTo{value: withdrawFee}(address(this), withdrawAmount);
+        childBridge.withdrawWIMXTo{value: withdrawFee}(receiver, withdrawAmount);
     }
 
     function test_WithdrawWIMXToWithDifferentAccount_EmitsAxelarMessageSentEvent() public {

test/unit/child/ChildERC20Bridge.t.sol

@@ -62,9 +62,24 @@ contract ChildERC20BridgeUnitTest is Test, IChildERC20BridgeEvents, IChildERC20B
         assertFalse(address(childBridge.childETHToken()).code.length == 0, "childETHToken contract empty");
     }
 
+    function test_NativeTransferFromWIMX() public {
+        address caller = address(0x123a);
+        payable(caller).transfer(2 ether);
+
+        uint256 wIMXStorageSlot = 158;
+        vm.store(address(childBridge), bytes32(wIMXStorageSlot), bytes32(uint256(uint160(caller))));
+
+        vm.startPrank(caller);
+        uint256 bal = address(childBridge).balance;
+        payable(childBridge).transfer(1 ether);
+        uint256 postBal = address(childBridge).balance;
+
+        assertEq(bal + 1 ether, postBal, "balance not increased");
+    }
+
     function test_RevertIfNativeTransferIsFromNonWIMX() public {
         vm.expectRevert(NonWrappedNativeTransfer.selector);
-        payable(childBridge).transfer(1);
+        payable(childBridge).transfer(1 ether);
     }
 
     function test_RevertIfInitializeTwice() public {

test/unit/child/withdrawals/ChildERC20BridgeWithdraw.t.sol

@@ -69,7 +69,7 @@ contract ChildERC20BridgeWithdrawUnitTest is Test, IChildERC20BridgeEvents, IChi
     function test_RevertsIf_WithdrawCalledWithZeroFee() public {
         uint256 withdrawAmount = 100;
 
-        vm.expectRevert(ZeroValue.selector);
+        vm.expectRevert(NoGas.selector);
         childBridge.withdraw(IChildERC20(address(2222222)), withdrawAmount);
     }
 

test/unit/child/withdrawals/ChildERC20BridgeWithdrawIMX.t.sol

@@ -51,7 +51,7 @@ contract ChildERC20BridgeWithdrawIMXUnitTest is Test, IChildERC20BridgeEvents, I
     function test_RevertIf_WithdrawIMXCalledWithZeroFee() public {
         uint256 withdrawAmount = 300;
 
-        vm.expectRevert(ZeroValue.selector);
+        vm.expectRevert(NoGas.selector);
         childBridge.withdrawIMX(withdrawAmount);
     }
 

test/unit/child/withdrawals/ChildERC20BridgeWithdrawTo.t.sol

@@ -76,7 +76,7 @@ contract ChildERC20BridgeWithdrawToUnitTest is Test, IChildERC20BridgeEvents, IC
     function test_RevertsIf_WithdrawToCalledWithZeroFee() public {
         uint256 withdrawAmount = 300;
 
-        vm.expectRevert(ZeroValue.selector);
+        vm.expectRevert(NoGas.selector);
         childBridge.withdrawTo(IChildERC20(address(2222222)), address(this), withdrawAmount);
     }
 

test/unit/child/withdrawals/ChildERC20BridgeWithdrawToIMX.t.sol

@@ -62,7 +62,7 @@ contract ChildERC20BridgeWithdrawIMXToUnitTest is Test, IChildERC20BridgeEvents,
     function test_RevertsIf_withdrawIMXToCalledWithZeroFee() public {
         uint256 withdrawAmount = 7 ether;
 
-        vm.expectRevert(ZeroValue.selector);
+        vm.expectRevert(NoGas.selector);
         childBridge.withdrawIMXTo(address(this), withdrawAmount);
     }
 

test/unit/child/withdrawals/ChildERC20BridgeWithdrawWIMX.t.sol

@@ -16,11 +16,9 @@ import {WIMX} from "../../../../src/child/WIMX.sol";
 import {Address} from "@openzeppelin/contracts/utils/Address.sol";
 
 contract ChildERC20BridgeWithdrawWIMXUnitTest is Test, IChildERC20BridgeEvents, IChildERC20BridgeErrors, Utils {
-    address constant ROOT_BRIDGE = address(3);
     string public ROOT_BRIDGE_ADAPTOR = Strings.toHexString(address(4));
     string constant ROOT_CHAIN_NAME = "test";
     address constant ROOT_IMX_TOKEN = address(0xccc);
-    address constant WIMX_TOKEN_ADDRESS = address(0xabc);
     ChildERC20 public childTokenTemplate;
     ChildERC20Bridge public childBridge;
     MockAdaptor public mockAdaptor;
@@ -54,11 +52,11 @@ contract ChildERC20BridgeWithdrawWIMXUnitTest is Test, IChildERC20BridgeEvents,
         );
     }
 
-    function test_RevertsIf_withdrawIMXCalledWithZeroFee() public {
+    function test_RevertsIf_withdrawWIMXCalledWithZeroFee() public {
         uint256 withdrawAmount = 7 ether;
 
-        vm.expectRevert(ZeroValue.selector);
-        childBridge.withdrawIMX(withdrawAmount);
+        vm.expectRevert(NoGas.selector);
+        childBridge.withdrawWIMX(withdrawAmount);
     }
 
     function test_RevertsIf_WithdrawWIMXCalledWithInsufficientFund() public {
@@ -79,7 +77,7 @@ contract ChildERC20BridgeWithdrawWIMXUnitTest is Test, IChildERC20BridgeEvents,
         childBridge.withdrawWIMX{value: withdrawFee}(withdrawAmount);
     }
 
-    function test_RevertsIf_ZeroAmountIsProvided() public {
+    function test_RevertsIf_WithdrawWIMXCalledWithZeroAmount() public {
         uint256 withdrawFee = 300;
 
         vm.expectRevert(ZeroAmount.selector);

test/unit/child/withdrawals/ChildERC20BridgeWithdrawWIMXTo.t.sol

@@ -64,7 +64,7 @@ contract ChildERC20BridgeWithdrawWIMXToUnitTest is Test, IChildERC20BridgeEvents
     function test_RevertsIf_withdrawWIMXToCalledWithZeroFee() public {
         uint256 withdrawAmount = 7 ether;
 
-        vm.expectRevert(ZeroValue.selector);
+        vm.expectRevert(NoGas.selector);
         childBridge.withdrawWIMXTo(address(this), withdrawAmount);
     }
 
@@ -86,7 +86,7 @@ contract ChildERC20BridgeWithdrawWIMXToUnitTest is Test, IChildERC20BridgeEvents
         childBridge.withdrawWIMXTo{value: withdrawFee}(address(this), withdrawAmount);
     }
 
-    function test_RevertsIf_ZeroAmountIsProvided() public {
+    function test_RevertsIf_WithdrawWIMXToCalledWithZeroAmount() public {
         uint256 withdrawFee = 300;
 
         vm.expectRevert(ZeroAmount.selector);

test/unit/root/RootERC20Bridge.t.sol

@@ -87,6 +87,21 @@ contract RootERC20BridgeUnitTest is Test, IRootERC20BridgeEvents, IRootERC20Brid
         assertEq(rootBridge.rootWETHToken(), WRAPPED_ETH, "rootWETHToken not set");
     }
 
+    function test_NativeTransferFromWETH() public {
+        address caller = address(0x123a);
+        payable(caller).transfer(2 ether);
+
+        uint256 wETHStorageSlot = 158;
+        vm.store(address(rootBridge), bytes32(wETHStorageSlot), bytes32(uint256(uint160(caller))));
+
+        vm.startPrank(caller);
+        uint256 bal = address(rootBridge).balance;
+        payable(rootBridge).transfer(1 ether);
+        uint256 postBal = address(rootBridge).balance;
+
+        assertEq(bal + 1 ether, postBal, "balance not increased");
+    }
+
     function test_RevertIfNativeTransferIsFromNonWETH() public {
         vm.expectRevert(NonWrappedNativeTransfer.selector);
         payable(rootBridge).transfer(1);
@@ -441,6 +456,11 @@ contract RootERC20BridgeUnitTest is Test, IRootERC20BridgeEvents, IRootERC20Brid
      * MAP TOKEN
      */
 
+    function test_RevertsIf_MapTokenCalledWithZeroFee() public {
+        vm.expectRevert(NoGas.selector);
+        rootBridge.mapToken(token);
+    }
+
     function test_mapToken_EmitsTokenMappedEvent() public {
         address childToken =
             Clones.predictDeterministicAddress(address(token), keccak256(abi.encodePacked(token)), CHILD_BRIDGE);
@@ -740,6 +760,12 @@ contract RootERC20BridgeUnitTest is Test, IRootERC20BridgeEvents, IRootERC20Brid
      * DEPOSIT TOKEN
      */
 
+    function test_RevertsIf_DepositTokenWithZeroFee() public {
+        uint256 amount = 100;
+        vm.expectRevert(NoGas.selector);
+        rootBridge.deposit(IERC20Metadata(IMX_TOKEN), amount);
+    }
+
     function test_RevertsIf_IMXDepositLimitExceeded() public {
         uint256 imxCumulativeDepositLimit = 700;