fix for when controller enabled but debt is 0

Author: hoytech

src/EulerSwap.sol

@@ -219,17 +219,15 @@ contract EulerSwap is IEulerSwap, EVCUtil {
     /// @dev After successful deposit, if the user has any outstanding controller-enabled debt, it attempts to repay it.
     /// @dev If all debt is repaid, the controller is automatically disabled to reduce gas costs in future operations.
     function depositAssets(address vault, uint256 amount) internal returns (uint256) {
-        uint256 debt = myDebt(vault);
         uint256 deposited;
 
-        if (debt > 0) {
-            uint256 repayAmount = amount > debt ? debt : amount;
+        if (IEVC(evc).isControllerEnabled(eulerAccount, vault)) {
+            uint256 debt = myDebt(vault);
+            uint256 repaid = IEVault(vault).repay(amount > debt ? debt : amount, eulerAccount);
 
-            IEVault(vault).repay(repayAmount, eulerAccount);
-
-            amount -= repayAmount;
-            debt -= repayAmount;
-            deposited += repayAmount;
+            amount -= repaid;
+            debt -= repaid;
+            deposited += repaid;
 
             if (debt == 0) {
                 IEVC(evc).call(vault, eulerAccount, 0, abi.encodeCall(IRiskManager.disableController, ()));

test/DepositFailures.t.sol

@@ -85,4 +85,26 @@ contract DepositFailuresTest is EulerSwapTestBase {
 
         assertEq(assetTST2.balanceOf(address(eulerSwap)), 1); // griefing transfer was untouched
     }
+
+    function test_manualEnableController() public monotonicHolderNAV {
+        vm.prank(holder);
+        evc.enableController(holder, address(eTST));
+
+        uint256 amountIn = 50e18;
+        uint256 amountOut =
+            periphery.quoteExactInput(address(eulerSwap), address(assetTST), address(assetTST2), amountIn);
+
+        assetTST.mint(address(this), amountIn);
+        assetTST.transfer(address(eulerSwap), amountIn);
+        eulerSwap.swap(0, amountOut, address(this), "");
+
+        // Swap the other way to measure gas impact
+
+        amountIn = 100e18;
+        amountOut = periphery.quoteExactInput(address(eulerSwap), address(assetTST2), address(assetTST), amountIn);
+
+        assetTST2.mint(address(this), amountIn);
+        assetTST2.transfer(address(eulerSwap), amountIn);
+        eulerSwap.swap(amountOut, 0, address(this), "");
+    }
 }