chore: port hardhat tests to foundry

contracts/test/ArbitrumMocks.sol

@@ -2,45 +2,94 @@
 pragma solidity ^0.8.0;
 
 contract ArbitrumMockErc20GatewayRouter {
+    address public gateway;
+
+    event OutboundTransferCalled(
+        address l1Token,
+        address to,
+        uint256 amount,
+        uint256 maxGas,
+        uint256 gasPriceBid,
+        bytes data
+    );
+
+    event OutboundTransferCustomRefundCalled(
+        address l1Token,
+        address refundTo,
+        address to,
+        uint256 amount,
+        uint256 maxGas,
+        uint256 gasPriceBid,
+        bytes data
+    );
+
+    function setGateway(address _gateway) external {
+        gateway = _gateway;
+    }
+
     function outboundTransferCustomRefund(
-        address,
-        address,
-        address,
-        uint256,
-        uint256,
-        uint256,
+        address _l1Token,
+        address _refundTo,
+        address _to,
+        uint256 _amount,
+        uint256 _maxGas,
+        uint256 _gasPriceBid,
         bytes calldata _data
     ) external payable returns (bytes memory) {
+        emit OutboundTransferCustomRefundCalled(_l1Token, _refundTo, _to, _amount, _maxGas, _gasPriceBid, _data);
         return _data;
     }
 
     function outboundTransfer(
-        address,
-        address,
-        uint256,
-        uint256,
-        uint256,
+        address _l1Token,
+        address _to,
+        uint256 _amount,
+        uint256 _maxGas,
+        uint256 _gasPriceBid,
         bytes calldata _data
     ) external payable returns (bytes memory) {
+        emit OutboundTransferCalled(_l1Token, _to, _amount, _maxGas, _gasPriceBid, _data);
         return _data;
     }
 
     function getGateway(address) external view returns (address) {
-        return address(this);
+        // Return custom gateway if set, otherwise return self (original behavior)
+        return gateway != address(0) ? gateway : address(this);
     }
 }
 
 contract Inbox {
+    event RetryableTicketCreated(
+        address destAddr,
+        uint256 l2CallValue,
+        uint256 maxSubmissionCost,
+        address excessFeeRefundAddress,
+        address callValueRefundAddress,
+        uint256 maxGas,
+        uint256 gasPriceBid,
+        bytes data
+    );
+
     function createRetryableTicket(
-        address,
-        uint256,
-        uint256,
-        address,
-        address,
-        uint256,
-        uint256,
-        bytes memory
-    ) external pure returns (uint256) {
+        address _destAddr,
+        uint256 _l2CallValue,
+        uint256 _maxSubmissionCost,
+        address _excessFeeRefundAddress,
+        address _callValueRefundAddress,
+        uint256 _maxGas,
+        uint256 _gasPriceBid,
+        bytes memory _data
+    ) external payable returns (uint256) {
+        emit RetryableTicketCreated(
+            _destAddr,
+            _l2CallValue,
+            _maxSubmissionCost,
+            _excessFeeRefundAddress,
+            _callValueRefundAddress,
+            _maxGas,
+            _gasPriceBid,
+            _data
+        );
         return 0;
     }
 }

contracts/test/MockCCTP.sol

@@ -4,24 +4,35 @@ pragma solidity ^0.8.0;
 import "../libraries/CircleCCTPAdapter.sol";
 
 contract MockCCTPMinter is ITokenMinter {
-    function burnLimitsPerMessage(address) external pure returns (uint256) {
-        return type(uint256).max;
+    uint256 private _burnLimit = type(uint256).max;
+
+    function setBurnLimit(uint256 limit) external {
+        _burnLimit = limit;
+    }
+
+    function burnLimitsPerMessage(address) external view returns (uint256) {
+        return _burnLimit;
     }
 }
 
 contract MockCCTPMessenger is ITokenMessenger {
     ITokenMinter private minter;
+    uint256 public depositForBurnCallCount;
+
+    event DepositForBurnCalled(uint256 amount, uint32 destinationDomain, bytes32 mintRecipient, address burnToken);
 
     constructor(ITokenMinter _minter) {
         minter = _minter;
     }
 
     function depositForBurn(
-        uint256,
-        uint32,
-        bytes32,
-        address
-    ) external pure returns (uint64 _nonce) {
+        uint256 _amount,
+        uint32 _destinationDomain,
+        bytes32 _mintRecipient,
+        address _burnToken
+    ) external returns (uint64 _nonce) {
+        depositForBurnCallCount++;
+        emit DepositForBurnCalled(_amount, _destinationDomain, _mintRecipient, _burnToken);
         return 0;
     }
 

contracts/test/MockERC20.sol

@@ -6,6 +6,42 @@ import { ERC20Permit } from "@openzeppelin/contracts-v4/token/ERC20/extensions/E
 import { ERC20 } from "@openzeppelin/contracts-v4/token/ERC20/ERC20.sol";
 import { SignatureChecker } from "@openzeppelin/contracts-v4/utils/cryptography/SignatureChecker.sol";
 
+/**
+ * @title MintableERC20
+ * @notice Simple mintable ERC20 with configurable decimals for testing.
+ */
+contract MintableERC20 is ERC20 {
+    uint8 private _decimals;
+
+    constructor(string memory name, string memory symbol, uint8 decimals_) ERC20(name, symbol) {
+        _decimals = decimals_;
+    }
+
+    function mint(address to, uint256 amount) external returns (bool) {
+        _mint(to, amount);
+        return true;
+    }
+
+    function burn(uint256 amount) external {
+        _burn(msg.sender, amount);
+    }
+
+    function burnFrom(address from, uint256 amount) external returns (bool) {
+        _spendAllowance(from, msg.sender, amount);
+        _burn(from, amount);
+        return true;
+    }
+
+    // ExpandedIERC20 compatibility
+    function addMinter(address) external {}
+    function addBurner(address) external {}
+    function resetOwner(address) external {}
+
+    function decimals() public view override returns (uint8) {
+        return _decimals;
+    }
+}
+
 /**
  * @title MockERC20
  * @notice Implements mocked ERC20 contract with various features.