fix tests, handle error condition

Author: hoytech

src/EulerSwap.sol

@@ -292,7 +292,7 @@ contract EulerSwap is IEulerSwap, EVCUtil {
     }
 
     /// @dev EulerSwap curve definition
-    /// Pre-conditions: x <= x0, 1 <= {px,py} <= 1e36, {x0,y0} <= type(uint112).max, c <= 1e18
+    /// Pre-conditions: 0 < x <= x0, 1 <= {px,py} <= 1e36, {x0,y0} <= type(uint112).max, c <= 1e18
     function f(uint256 x, uint256 px, uint256 py, uint256 x0, uint256 y0, uint256 c) internal pure returns (uint256) {
         unchecked {
             uint256 v = Math.mulDiv(px * (x0 - x), c * x + (1e18 - c) * x0, x * 1e18, Math.Rounding.Ceil);

src/EulerSwapPeriphery.sol

@@ -15,6 +15,7 @@ contract EulerSwapPeriphery is IEulerSwapPeriphery {
     error SwapLimitExceeded();
     error AmountOutLessThanMin();
     error AmountInMoreThanMax();
+    error Overflow();
 
     /// @inheritdoc IEulerSwapPeriphery
     function swapExactIn(address eulerSwap, address tokenIn, address tokenOut, uint256 amountIn, uint256 amountOutMin)
@@ -230,9 +231,6 @@ contract EulerSwapPeriphery is IEulerSwapPeriphery {
 
     //////////////////////////////
 
-
-    // Exact version starts here.
-    // Strategy is to re-calculate everything using f() and fInverse() and see where things break.
     function search(
         IEulerSwap eulerSwap,
         uint112 reserve0,
@@ -280,6 +278,7 @@ contract EulerSwapPeriphery is IEulerSwapPeriphery {
             // exact out
             if (asset0IsInput) {
                 // swap Y out and X in
+                require(reserve1 > amount, SwapLimitExceeded());
                 yNew = reserve1 - amount;
                 if (yNew < y0) {
                     // remain on g()
@@ -291,6 +290,7 @@ contract EulerSwapPeriphery is IEulerSwapPeriphery {
                 output = xNew > reserve0 ? xNew - reserve0 : 0;
             } else {
                 // swap X out and Y in
+                require(reserve0 > amount, SwapLimitExceeded());
                 xNew = reserve0 - amount;
                 if (xNew < x0) {
                     // remain on f()
@@ -305,11 +305,11 @@ contract EulerSwapPeriphery is IEulerSwapPeriphery {
     }
 
     /// @dev EulerSwap curve definition
-    /// Pre-conditions: x <= x0, 1 <= {px,py} <= 1e36, {x0,y0} <= type(uint112).max, c <= 1e18
+    /// Pre-conditions: 0 < x <= x0, 1 <= {px,py} <= 1e36, {x0,y0} <= type(uint112).max, c <= 1e18
     function f(uint256 x, uint256 px, uint256 py, uint256 x0, uint256 y0, uint256 c) internal pure returns (uint256) {
         unchecked {
             uint256 v = Math.mulDiv(px * (x0 - x), c * x + (1e18 - c) * x0, x * 1e18, Math.Rounding.Ceil);
-            require(v <= type(uint248).max, "HELP");
+            require(v <= type(uint248).max, Overflow());
             return y0 + (v + (py - 1)) / py;
         }
     }

test/AltDecimals.t.sol

@@ -22,7 +22,7 @@ contract AltDecimals is EulerSwapTestBase {
         assetTST.transfer(address(eulerSwap), amount);
 
         {
-            uint256 qPlus = q + 1;
+            uint256 qPlus = q + MAX_QUOTE_ERROR + 1;
             vm.expectRevert();
             eulerSwap.swap(0, qPlus, address(this), "");
         }
@@ -62,7 +62,7 @@ contract AltDecimals is EulerSwapTestBase {
         assetTST.transfer(address(eulerSwap), amount);
 
         {
-            uint256 qPlus = q + 1;
+            uint256 qPlus = q + MAX_QUOTE_ERROR + 1;
             vm.expectRevert();
             eulerSwap.swap(0, qPlus, address(this), "");
         }

test/EulerSwapTest.t.sol

@@ -159,7 +159,7 @@ contract EulerSwapTest is EulerSwapTestBase {
             t1.transfer(address(eulerSwap), amount);
 
             {
-                uint256 qPlus = q + 1;
+                uint256 qPlus = q + MAX_QUOTE_ERROR + 1;
                 vm.expectRevert();
                 if (dir) eulerSwap.swap(0, qPlus, address(this), "");
                 else eulerSwap.swap(qPlus, 0, address(this), "");

test/EulerSwapTestBase.t.sol

@@ -12,6 +12,8 @@ import {HookMiner} from "v4-periphery/src/utils/HookMiner.sol";
 import {Hooks} from "@uniswap/v4-core/src/libraries/Hooks.sol";
 
 contract EulerSwapTestBase is EVaultTestBase {
+    uint256 public constant MAX_QUOTE_ERROR = 4;
+
     address public depositor = makeAddr("depositor");
     address public creator = makeAddr("creator");
     address public holder = makeAddr("holder");

test/Fees.t.sol

@@ -41,7 +41,7 @@ contract FeesTest is EulerSwapTestBase {
         // Pulling out one extra reverts...
 
         vm.expectRevert(EulerSwap.CurveViolation.selector);
-        eulerSwap.swap(0, amountOut + 1, address(this), "");
+        eulerSwap.swap(0, amountOut + MAX_QUOTE_ERROR + 1, address(this), "");
 
         // Just right:
 
@@ -92,7 +92,7 @@ contract FeesTest is EulerSwapTestBase {
         // Pulling out one extra reverts...
 
         vm.expectRevert(EulerSwap.CurveViolation.selector);
-        eulerSwap.swap(0, amountOut + 1, address(this), "");
+        eulerSwap.swap(0, amountOut + MAX_QUOTE_ERROR + 1, address(this), "");
 
         // Just right:
 

test/PreserveNav.t.sol

@@ -47,7 +47,7 @@ contract PreserveNav is EulerSwapTestBase {
             t1.transfer(address(eulerSwap), amount1);
 
             {
-                uint256 qPlus = q + 1;
+                uint256 qPlus = q + MAX_QUOTE_ERROR + 1;
                 vm.expectRevert();
                 if (dir1) eulerSwap.swap(0, qPlus, address(this), "");
                 else eulerSwap.swap(qPlus, 0, address(this), "");
@@ -71,7 +71,7 @@ contract PreserveNav is EulerSwapTestBase {
             t1.transfer(address(eulerSwap), amount2);
 
             {
-                uint256 qPlus = q + 1;
+                uint256 qPlus = q + MAX_QUOTE_ERROR + 1;
                 vm.expectRevert();
                 if (dir2) eulerSwap.swap(0, qPlus, address(this), "");
                 else eulerSwap.swap(qPlus, 0, address(this), "");