fix quoting when borrowVault is address(0)

Spearbit #15

Author: hoytech

src/libraries/QuoteLib.sol

@@ -129,7 +129,8 @@ library QuoteLib {
         {
             IEVault supplyVault = IEVault(asset0IsInput ? sParams.supplyVault0 : sParams.supplyVault1);
             IEVault borrowVault = IEVault(asset0IsInput ? sParams.borrowVault0 : sParams.borrowVault1);
-            uint256 maxDeposit = borrowVault.debtOf(eulerAccount) + supplyVault.maxDeposit(eulerAccount);
+            uint256 maxDeposit = supplyVault.maxDeposit(eulerAccount);
+            if (address(borrowVault) != address(0)) maxDeposit += borrowVault.debtOf(eulerAccount);
             if (maxDeposit < inLimit) inLimit = maxDeposit;
         }
 
@@ -153,12 +154,13 @@ library QuoteLib {
                     if (supplyCash < outLimit) outLimit = supplyCash;
                 } else {
                     // Sufficient cash to cover full withdrawal, so limiting factor is cash in borrowVault
-                    uint256 cashLimit = supplyBalance + borrowVault.cash();
+                    uint256 cashLimit = supplyBalance;
+                    if (address(borrowVault) != address(0)) cashLimit += borrowVault.cash();
                     if (cashLimit < outLimit) outLimit = cashLimit;
                 }
             }
 
-            {
+            if (address(borrowVault) != address(0)) {
                 (, uint16 borrowCapEncoded) = borrowVault.caps();
                 uint256 borrowCap = decodeCap(uint256(borrowCapEncoded));
                 if (borrowCap != type(uint256).max) {

test/SplitVaults.t.sol

@@ -38,6 +38,10 @@ contract SplitVaults is EulerSwapTestBase {
         mintAndDeposit(depositor, eTST_alt, 50e18);
         mintAndDeposit(depositor, eTST2_alt, 50e18);
 
+        installAltBorrowVaults(eTST_alt, eTST2_alt);
+    }
+
+    function installAltBorrowVaults(IEVault bv0, IEVault bv1) internal {
         // Setup EulerSwap
         uint112 reserve0 = 60e18;
         uint112 reserve1 = 60e18;
@@ -46,8 +50,8 @@ contract SplitVaults is EulerSwapTestBase {
             getEulerSwapParams(reserve0, reserve1, 1e18, 1e18, 0.85e18, 0.85e18, 0, address(0), 0, address(0));
         IEulerSwap.InitialState memory initialState = IEulerSwap.InitialState({reserve0: reserve0, reserve1: reserve1});
 
-        sParams.borrowVault0 = address(eTST_alt);
-        sParams.borrowVault1 = address(eTST2_alt);
+        sParams.borrowVault0 = address(bv0);
+        sParams.borrowVault1 = address(bv1);
 
         eulerSwap = createEulerSwapFull(sParams, dParams, initialState);
     }
@@ -155,4 +159,16 @@ contract SplitVaults is EulerSwapTestBase {
 
         validateOutputSwapPossible(assetTST, assetTST2, 3e18 - 1);
     }
+
+    function test_splitVault_nullBorrowVault0() public isSwappable {
+        installAltBorrowVaults(IEVault(address(0)), eTST2_alt);
+    }
+
+    function test_splitVault_nullBorrowVault1() public isSwappable {
+        installAltBorrowVaults(eTST_alt, IEVault(address(0)));
+    }
+
+    function test_splitVault_nullBorrowVaultBoth() public isSwappable {
+        installAltBorrowVaults(IEVault(address(0)), IEVault(address(0)));
+    }
 }