test: demonstrate non-reentrancy guaranteed by CREATE2 address collision

test/ERC721ForERC20.t.sol

@@ -9,6 +9,7 @@ import {ERC20Test} from "./ERC20Test.t.sol";
 
 import {ERC721Token} from "../src/ERC721SwapperLib.sol";
 import {ERC721ForERC20Swap, IERC20} from "../src/ERC721ForERC20/ERC721ForERC20Swap.sol";
+import {ERC721ForERC20SwapperDeployer} from "../src/ERC721ForERC20/ERC721ForERC20SwapperDeployer.gen.sol";
 import {InsufficientBalance, Disbursement, Parties} from "../src/TypesAndConstants.sol";
 
 import {IERC721Errors} from "@openzeppelin/contracts/interfaces/draft-IERC6093.sol";
@@ -50,6 +51,11 @@ contract ERC721ForERC20Test is ERC721ForXTest, ERC20Test {
         return abi.encode(_asSwap(t), salt);
     }
 
+    /// @inheritdoc ERC721ForXTest
+    function _fillSelector() internal pure override returns (bytes4) {
+        return ERC721ForERC20SwapperDeployer.fill.selector;
+    }
+
     /// @inheritdoc ERC721ForXTest
     function _fill(ERC721TestCase memory t) internal override {
         factory.fill(_asSwap(t), t.base.salt);

test/ERC721ForNative.t.sol

@@ -9,6 +9,7 @@ import {NativeTokenTest} from "./NativeTokenTest.t.sol";
 
 import {ERC721Token} from "../src/ERC721SwapperLib.sol";
 import {ERC721ForNativeSwap} from "../src/ERC721ForNative/ERC721ForNativeSwap.sol";
+import {ERC721ForNativeSwapperDeployer} from "../src/ERC721ForNative/ERC721ForNativeSwapperDeployer.gen.sol";
 import {InsufficientBalance, Disbursement, Parties} from "../src/TypesAndConstants.sol";
 
 import {IERC721Errors} from "@openzeppelin/contracts/interfaces/draft-IERC6093.sol";
@@ -44,6 +45,11 @@ contract ERC721ForNativeTest is ERC721ForXTest, NativeTokenTest {
         return abi.encode(_asSwap(t), salt);
     }
 
+    /// @inheritdoc ERC721ForXTest
+    function _fillSelector() internal pure override returns (bytes4) {
+        return ERC721ForNativeSwapperDeployer.fill.selector;
+    }
+
     /// @inheritdoc ERC721ForXTest
     function _fill(ERC721TestCase memory t) internal override {
         _fill(t, t.base.native.callValue);

test/ERC721ForXTest.t.sol

@@ -39,6 +39,8 @@ abstract contract ERC721ForXTest is SwapperTestBase {
 
     function _encodedSwapAndSalt(ERC721TestCase memory, bytes32) internal view virtual returns (bytes memory);
 
+    function _fillSelector() internal pure virtual returns (bytes4);
+
     /// @dev Fills the swap defined by the test case.
     function _fill(ERC721TestCase memory) internal virtual;
 
@@ -278,6 +280,23 @@ abstract contract ERC721ForXTest is SwapperTestBase {
         vm.stopPrank();
     }
 
+    function testNonReentrant(ERC721TestCase memory t)
+        external
+        assumeValidTest(t.base)
+        assumePaymentsValid(t.base)
+        assumeSufficientPayment(t.base)
+        assumeValidPlatformFee(t.base)
+        assumeApproving(t.base)
+    {
+        token.setPostTransferCall(
+            address(factory), abi.encodePacked(_fillSelector(), _encodedSwapAndSalt(t, t.base.salt))
+        );
+
+        // The most precise way to detect a redeployment is to see that CREATE2 reverts without any return data.
+        // Inspection of the trace with `forge test -vvvv` is necessary to see the [CreationCollision] error.
+        _testFill(t, abi.encodeWithSelector(ETDeployer.Create2EmptyRevert.selector));
+    }
+
     function testGas() external {
         Disbursement[5] memory thirdParty;
         uint128 total = 1 ether;

test/MultiERC721ForERC20.t.sol

@@ -9,6 +9,7 @@ import {ERC20Test} from "./ERC20Test.t.sol";
 
 import {MultiERC721Token} from "../src/ERC721SwapperLib.sol";
 import {MultiERC721ForERC20Swap, IERC20} from "../src/MultiERC721ForERC20/MultiERC721ForERC20Swap.sol";
+import {MultiERC721ForERC20SwapperDeployer} from "../src/MultiERC721ForERC20/MultiERC721ForERC20SwapperDeployer.gen.sol";
 import {InsufficientBalance, Disbursement, Parties} from "../src/TypesAndConstants.sol";
 
 import {IERC721Errors} from "@openzeppelin/contracts/interfaces/draft-IERC6093.sol";
@@ -58,6 +59,11 @@ contract MultiERC721ForERC20Test is ERC721ForXTest, ERC20Test {
         return abi.encode(_asSwap(t), salt);
     }
 
+    /// @inheritdoc ERC721ForXTest
+    function _fillSelector() internal pure override returns (bytes4) {
+        return MultiERC721ForERC20SwapperDeployer.fill.selector;
+    }
+
     /// @inheritdoc ERC721ForXTest
     function _fill(ERC721TestCase memory t) internal override {
         factory.fill(_asSwap(t), t.base.salt);

test/MultiERC721ForNative.t.sol

@@ -9,6 +9,8 @@ import {NativeTokenTest} from "./NativeTokenTest.t.sol";
 
 import {MultiERC721Token} from "../src/ERC721SwapperLib.sol";
 import {MultiERC721ForNativeSwap} from "../src/MultiERC721ForNative/MultiERC721ForNativeSwap.sol";
+import {MultiERC721ForNativeSwapperDeployer} from
+    "../src/MultiERC721ForNative/MultiERC721ForNativeSwapperDeployer.gen.sol";
 import {InsufficientBalance, Disbursement, Parties} from "../src/TypesAndConstants.sol";
 
 import {IERC721Errors} from "@openzeppelin/contracts/interfaces/draft-IERC6093.sol";
@@ -52,6 +54,11 @@ contract MultiERC721ForNativeTest is ERC721ForXTest, NativeTokenTest {
         return abi.encode(_asSwap(t), salt);
     }
 
+    /// @inheritdoc ERC721ForXTest
+    function _fillSelector() internal pure override returns (bytes4) {
+        return MultiERC721ForNativeSwapperDeployer.fill.selector;
+    }
+
     /// @inheritdoc ERC721ForXTest
     function _fill(ERC721TestCase memory t) internal override {
         _fill(t, t.base.native.callValue);

test/SwapperTestBase.t.sol

@@ -16,6 +16,7 @@ import {
 
 import {ERC721, IERC721} from "@openzeppelin/contracts/token/ERC721/ERC721.sol";
 import {IERC20} from "@openzeppelin/contracts/interfaces/IERC20.sol";
+import {Address} from "@openzeppelin/contracts/utils/Address.sol";
 import {Math} from "@openzeppelin/contracts/utils/math/Math.sol";
 
 contract Token is ERC721 {
@@ -28,6 +29,28 @@ contract Token is ERC721 {
     function exists(uint256 tokenId) external view returns (bool) {
         return _ownerOf(tokenId) != address(0);
     }
+
+    /**
+     * @dev If non-zero, this address is called after transferFrom() to enable testing of reentrancy. Although an attack
+     * would typically be performed by a Party, the token transfer is the only common function call in all tests so is
+     * the cleanest way to insert a reentrancy hook.
+     */
+    address private _callPostTransfer;
+
+    bytes private _postTransferCallData;
+
+    function setPostTransferCall(address a, bytes calldata data) public {
+        _callPostTransfer = a;
+        _postTransferCallData = data;
+    }
+
+    function transferFrom(address from, address to, uint256 tokenId) public override {
+        super.transferFrom(from, to, tokenId);
+
+        if (_callPostTransfer != address(0)) {
+            Address.functionCall(_callPostTransfer, _postTransferCallData);
+        }
+    }
 }
 
 interface ITestEvents is ISwapperEvents {