feat: add tests for withdraw, fee and make it DRY

foundry/test/TychoRouterTestSetup.sol

@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.13;
+
+import "@src/TychoRouter.sol";
+import "./Constants.sol";
+import "./mock/MockERC20.sol";
+
+contract TychoRouterTestSetup is Test, Constants {
+    TychoRouter tychoRouter;
+    address executorSetter;
+    address permit2Address = address(0x000000000022D473030F116dDEE9F6B43aC78BA3);
+    MockERC20[] tokens;
+
+    function setUp() public {
+        vm.startPrank(ADMIN);
+        tychoRouter = new TychoRouter(permit2Address);
+        tychoRouter.grantRole(keccak256("EXECUTOR_SETTER_ROLE"), BOB);
+        tychoRouter.grantRole(keccak256("FUND_RESCUER_ROLE"), FUND_RESCUER);
+        tychoRouter.grantRole(keccak256("FEE_SETTER_ROLE"), FEE_SETTER);
+        executorSetter = BOB;
+        deployDummyContract();
+        vm.stopPrank();
+
+        vm.startPrank(BOB);
+        tokens.push(new MockERC20("Token A", "A"));
+        tokens.push(new MockERC20("Token B", "B"));
+        tokens.push(new MockERC20("Token C", "C"));
+        vm.stopPrank();
+    }
+
+    /**
+     * @dev Deploys a dummy contract with non-empty bytecode
+     */
+    function deployDummyContract() internal {
+        bytes memory minimalBytecode = hex"01"; // Single-byte bytecode
+        vm.etch(DUMMY, minimalBytecode); // Deploy minimal bytecode
+    }
+}