refactor: Move contract code-checking logic to SwapExecutionDispatcher

I was inspired to do this because, when disabling the slither check for the delegatecall when calling the swap executor, I realized it's not clear from the same contract that we have already checked for contract code existence when setting the executor. This made me feel uneasy, as this contract can then not stand alone and must rely on the higher level contract to safely check for code existence, otherwise the delegatecall is unsafe. Keeping this logic in a separate contract seems error-prone to me, as we may remove the check for code existence without immediately realizing the implications of doing so.

For this reason I have organized it as follows:
- Logic/tests relating to proper roles/access control in the main TychoRouter.
- Lower-level logic/tests that checks contract validity before setting the executor in the SwapExecutionDispatcher

foundry/test/Constants.sol

@@ -14,4 +14,12 @@ contract Constants is Test {
     address DUMMY = makeAddr("dummy");
 
     address WETH_ADDR = address(0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2);
+
+    /**
+     * @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
+    }
 }

foundry/test/SwapExecutionDispatcher.t.sol

@@ -20,28 +20,62 @@ contract SwapExecutionDispatcherExposed is SwapExecutionDispatcher {
         return _decodeExecutorAndSelector(data);
     }
 
-    function setSwapExecutor(address target) external {
-        swapExecutors[target] = true;
+    function exposedSetSwapExecutor(address target) external {
+        _setSwapExecutor(target);
+    }
+
+    function exposedRemoveSwapExecutor(address target) external {
+        _removeSwapExecutor(target);
     }
 }
 
-contract SwapExecutionDispatcherTest is TychoRouterTestSetup {
+contract SwapExecutionDispatcherTest is Constants {
     SwapExecutionDispatcherExposed dispatcherExposed;
 
-    function setupExecutionDispatcher() public {
+    event ExecutorSet(address indexed executor);
+
+    function setUp() public {
         uint256 forkBlock = 20673900;
         vm.createSelectFork(vm.rpcUrl("mainnet"), forkBlock);
         dispatcherExposed = new SwapExecutionDispatcherExposed();
-        dispatcherExposed.setSwapExecutor(
-            address(0xe592557AB9F4A75D992283fD6066312FF013ba3d)
-        );
         deal(WETH_ADDR, address(dispatcherExposed), 15000000000000000000);
+        deployDummyContract();
     }
 
-    function testCallSwapExecutor1() public {
+    function testSetValidExecutor() public {
+        vm.expectEmit();
+        // Define the event we expect to be emitted at the next step
+        emit ExecutorSet(DUMMY);
+        dispatcherExposed.exposedSetSwapExecutor(DUMMY);
+        assert(dispatcherExposed.swapExecutors(DUMMY) == true);
+    }
+
+    function testRemoveExecutor() public {
+        dispatcherExposed.exposedSetSwapExecutor(DUMMY);
+        dispatcherExposed.exposedRemoveSwapExecutor(DUMMY);
+        assert(dispatcherExposed.swapExecutors(DUMMY) == false);
+    }
+
+    function testRemoveUnSetExecutor() public {
+        dispatcherExposed.exposedRemoveSwapExecutor(BOB);
+        assert(dispatcherExposed.swapExecutors(BOB) == false);
+    }
+
+    function testSetExecutorNonContract() public {
+        vm.expectRevert(
+            abi.encodeWithSelector(
+                SwapExecutionDispatcher__NonContractExecutor.selector
+            )
+        );
+        dispatcherExposed.exposedSetSwapExecutor(BOB);
+    }
+
+    function testCallSwapExecutor() public {
         // Test case taken from existing transaction
         // 0x755d603962b30f416cf3eefae8d55204d6ffdf746465b2a94aca216faab63804
-        setupExecutionDispatcher();
+        dispatcherExposed.exposedSetSwapExecutor(
+            address(0xe592557AB9F4A75D992283fD6066312FF013ba3d)
+        );
         bytes memory data =
             hex"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";
         uint256 givenAmount = 15000000000000000000;
@@ -54,7 +88,9 @@ contract SwapExecutionDispatcherTest is TychoRouterTestSetup {
         // Test case taken from existing transaction
         // 0x755d603962b30f416cf3eefae8d55204d6ffdf746465b2a94aca216faab63804
         // No selector is passed, so the standard swap selector should be used
-        setupExecutionDispatcher();
+        dispatcherExposed.exposedSetSwapExecutor(
+            address(0xe592557AB9F4A75D992283fD6066312FF013ba3d)
+        );
         bytes memory data =
             hex"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";
         uint256 givenAmount = 15000000000000000000;
@@ -65,7 +101,9 @@ contract SwapExecutionDispatcherTest is TychoRouterTestSetup {
 
     function testCallSwapExecutorCallFailed() public {
         // Bad data is provided to an approved swap executor - causing the call to fail
-        setupExecutionDispatcher();
+        dispatcherExposed.exposedSetSwapExecutor(
+            address(0xe592557AB9F4A75D992283fD6066312FF013ba3d)
+        );
         bytes memory data =
             hex"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";
         vm.expectRevert();
@@ -73,7 +111,6 @@ contract SwapExecutionDispatcherTest is TychoRouterTestSetup {
     }
 
     function testCallSwapExecutorUnapprovedExecutor() public {
-        setupExecutionDispatcher();
         bytes memory data =
             hex"5d622C9053b8FFB1B3465495C8a42E603632bA70aabbccdd1111111111111111";
         vm.expectRevert();
@@ -81,7 +118,6 @@ contract SwapExecutionDispatcherTest is TychoRouterTestSetup {
     }
 
     function testDecodeExecutorAndSelector() public {
-        setupExecutionDispatcher();
         bytes memory data =
             hex"6611e616d2db3244244a54c754a16dd3ac7ca7a2aabbccdd1111111111111111";
         (address executor, bytes4 selector, bytes memory protocolData) =

foundry/test/TychoRouter.t.sol

@@ -20,33 +20,13 @@ contract TychoRouterTest is TychoRouterTestSetup {
         address indexed token, uint256 amount, address indexed receiver
     );
 
-    function testSetValidExecutor() public {
+    function testSetExecutorValidRole() public {
         vm.startPrank(executorSetter);
-        vm.expectEmit();
-        // Define the event we expect to be emitted at the next step
-        emit ExecutorSet(DUMMY);
-
         tychoRouter.setSwapExecutor(DUMMY);
         vm.stopPrank();
-
         assert(tychoRouter.swapExecutors(DUMMY) == true);
     }
 
-    function testRemoveExecutor() public {
-        vm.startPrank(executorSetter);
-        tychoRouter.setSwapExecutor(DUMMY);
-        tychoRouter.removeSwapExecutor(DUMMY);
-        vm.stopPrank();
-        assert(tychoRouter.swapExecutors(DUMMY) == false);
-    }
-
-    function testRemoveUnSetExecutor() public {
-        vm.startPrank(executorSetter);
-        tychoRouter.removeSwapExecutor(BOB);
-        vm.stopPrank();
-        assert(tychoRouter.swapExecutors(BOB) == false);
-    }
-
     function testRemoveExecutorMissingSetterRole() public {
         vm.expectRevert();
         tychoRouter.removeSwapExecutor(BOB);
@@ -57,15 +37,6 @@ contract TychoRouterTest is TychoRouterTestSetup {
         tychoRouter.setSwapExecutor(DUMMY);
     }
 
-    function testSetExecutorNonContract() public {
-        vm.startPrank(executorSetter);
-        vm.expectRevert(
-            abi.encodeWithSelector(TychoRouter__NonContractExecutor.selector)
-        );
-        tychoRouter.setSwapExecutor(BOB);
-        vm.stopPrank();
-    }
-
     function testSetValidVerifier() public {
         vm.startPrank(executorSetter);
         vm.expectEmit();

foundry/test/TychoRouterTestSetup.sol

@@ -28,14 +28,6 @@ contract TychoRouterTestSetup is Test, Constants {
         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
-    }
-
     /**
      * @dev Mints tokens to the given address
      * @param amount The amount of tokens to mint