fix(univ4): Append callback data instead of prepending

Bring back tests on the executor level. This way the executor can actually be used alone

--- don't change below this line ---
ENG-4222 Took 12 minutes

foundry/src/TychoRouter.sol

@@ -449,9 +449,9 @@ contract TychoRouter is
         returns (bytes memory)
     {
         require(data.length >= 20, "Invalid data length");
-        address executor = address(uint160(bytes20(data[0:20])));
+        bytes4 selector = bytes4(data[data.length - 4:]);
-        bytes4 selector = bytes4(data[20:24]);
+        address executor = address(uint160(bytes20(data[data.length - 24:data.length - 4])));
-        bytes memory protocolData = data[24:];
+        bytes memory protocolData = data[:data.length - 24];
 
         if (!executors[executor]) {
             revert ExecutionDispatcher__UnapprovedExecutor();

foundry/src/executors/UniswapV4Executor.sol

@@ -16,7 +16,6 @@ import {V4Router} from "@uniswap/v4-periphery/src/V4Router.sol";
 import {Actions} from "@uniswap/v4-periphery/src/libraries/Actions.sol";
 import {IV4Router} from "@uniswap/v4-periphery/src/interfaces/IV4Router.sol";
 import {PathKey} from "@uniswap/v4-periphery/src/libraries/PathKey.sol";
-import "lib/forge-std/src/console.sol";
 
 error UniswapV4Executor__InvalidDataLength();
 
@@ -47,7 +46,7 @@ contract UniswapV4Executor is IExecutor, V4Router {
             UniswapV4Executor.UniswapV4Pool[] memory pools
         ) = _decodeData(data);
 
-        bytes memory fullData;
+        bytes memory swapData;
         if (pools.length == 1) {
             PoolKey memory key = PoolKey({
                 currency0: Currency.wrap(zeroForOne ? tokenIn : tokenOut),
@@ -75,9 +74,8 @@ contract UniswapV4Executor is IExecutor, V4Router {
             );
             params[1] = abi.encode(key.currency0, amountIn);
             params[2] = abi.encode(key.currency1, amountOutMin);
-            bytes memory swapData = abi.encode(actions, params);
+            swapData = abi.encode(actions, params);
-            fullData =
+
-                abi.encodePacked(callbackExecutor, callbackSelector, swapData);
         } else {
             PathKey[] memory path = new PathKey[](pools.length);
             for (uint256 i = 0; i < pools.length; i++) {
@@ -109,11 +107,10 @@ contract UniswapV4Executor is IExecutor, V4Router {
             );
             params[1] = abi.encode(currencyIn, amountIn);
             params[2] = abi.encode(Currency.wrap(tokenOut), amountOutMin);
-            bytes memory swapData = abi.encode(actions, params);
+            swapData = abi.encode(actions, params);
-            fullData =
-                abi.encodePacked(callbackExecutor, callbackSelector, swapData);
         }
-
+            bytes memory fullData =
+                                abi.encodePacked( swapData, callbackExecutor, callbackSelector);
         uint256 tokenOutBalanceBefore;
 
         tokenOutBalanceBefore = tokenOut == address(0)

foundry/test/executors/UniswapV4Executor.t.sol

@@ -98,4 +98,80 @@ contract UniswapV4ExecutorTest is Test, Constants {
         assertEq(decodedPools[1].fee, pool2Fee);
         assertEq(decodedPools[1].tickSpacing, tickSpacing2);
     }
+
+    function testSingleSwap() public {
+        uint256 amountIn = 100 ether;
+        deal(USDE_ADDR, address(uniswapV4Exposed), amountIn);
+        uint256 usdeBalanceBeforePool = USDE.balanceOf(poolManager);
+        uint256 usdeBalanceBeforeSwapExecutor =
+                            USDE.balanceOf(address(uniswapV4Exposed));
+
+        UniswapV4Executor.UniswapV4Pool[] memory pools =
+                    new UniswapV4Executor.UniswapV4Pool[](1);
+        pools[0] = UniswapV4Executor.UniswapV4Pool({
+            intermediaryToken: USDT_ADDR,
+            fee: uint24(100),
+            tickSpacing: int24(1)
+        });
+
+        bytes memory data = UniswapV4Utils.encodeExactInput(
+            USDE_ADDR,
+            USDT_ADDR,
+            uint256(1),
+            true,
+            address(uniswapV4Exposed),
+            SafeCallback.unlockCallback.selector,
+            pools
+        );
+
+        uint256 amountOut = uniswapV4Exposed.swap(amountIn, data);
+        assertEq(USDE.balanceOf(poolManager), usdeBalanceBeforePool + amountIn);
+        assertEq(
+            USDE.balanceOf(address(uniswapV4Exposed)),
+            usdeBalanceBeforeSwapExecutor - amountIn
+        );
+        assertTrue(USDT.balanceOf(address(uniswapV4Exposed)) == amountOut);
+    }
+
+    function testMultipleSwap() public {
+        // USDE -> USDT -> WBTC
+        uint256 amountIn = 100 ether;
+        deal(USDE_ADDR, address(uniswapV4Exposed), amountIn);
+        uint256 usdeBalanceBeforePool = USDE.balanceOf(poolManager);
+        uint256 usdeBalanceBeforeSwapExecutor =
+                            USDE.balanceOf(address(uniswapV4Exposed));
+
+
+        UniswapV4Executor.UniswapV4Pool[] memory pools =
+                    new UniswapV4Executor.UniswapV4Pool[](2);
+        pools[0] = UniswapV4Executor.UniswapV4Pool({
+            intermediaryToken: USDT_ADDR,
+            fee: uint24(100),
+            tickSpacing: int24(1)
+        });
+        pools[1] = UniswapV4Executor.UniswapV4Pool({
+            intermediaryToken: WBTC_ADDR,
+            fee: uint24(3000),
+            tickSpacing: int24(60)
+        });
+
+        bytes memory data = UniswapV4Utils.encodeExactInput(
+            USDE_ADDR,
+            WBTC_ADDR,
+            uint256(1),
+            true,
+            address(uniswapV4Exposed),
+            SafeCallback.unlockCallback.selector,
+            pools
+        );
+
+        uint256 amountOut = uniswapV4Exposed.swap(amountIn, data);
+        assertEq(USDE.balanceOf(poolManager), usdeBalanceBeforePool + amountIn);
+        assertEq(
+            USDE.balanceOf(address(uniswapV4Exposed)),
+            usdeBalanceBeforeSwapExecutor - amountIn
+        );
+        assertTrue(IERC20(WBTC_ADDR).balanceOf(address(uniswapV4Exposed)) == amountOut);
+    }
+
 }