Merge pull request #84 from primitivefinance/test/constant-sum-tests

Fix ConstantSum strategy

src/ConstantSum/ConstantSum.sol

@@ -2,7 +2,9 @@
 pragma solidity 0.8.22;
 
 import {
-    FixedPointMathLib, computeTradingFunction
+    FixedPointMathLib,
+    computeTradingFunction,
+    computeDeltaLiquidity
 } from "./ConstantSumMath.sol";
 import {
     decodePriceUpdate,
@@ -33,6 +35,9 @@ enum UpdateCode {
 contract ConstantSum is PairStrategy {
     using FixedPointMathLib for uint256;
 
+    /// @notice Thrown when the expected liquidity is not met.
+    error InvalidDeltaLiquidity();
+
     /// @inheritdoc IStrategy
     string public constant name = "ConstantSum";
 
@@ -74,6 +79,84 @@ contract ConstantSum is PairStrategy {
         return (valid, invariant, reserves, totalLiquidity);
     }
 
+    function validateAllocate(
+        address,
+        uint256 poolId,
+        Pool memory pool,
+        bytes calldata data
+    )
+        external
+        view
+        override
+        returns (
+            bool valid,
+            int256 invariant,
+            uint256[] memory deltas,
+            uint256 deltaLiquidity
+        )
+    {
+        (uint256 deltaX, uint256 deltaY, uint256 minDeltaL) =
+            abi.decode(data, (uint256, uint256, uint256));
+
+        deltaLiquidity =
+            computeDeltaLiquidity(deltaX, deltaY, internalParams[poolId].price);
+        if (deltaLiquidity < minDeltaL) revert InvalidDeltaLiquidity();
+
+        deltas = new uint256[](2);
+        deltas[0] = deltaX;
+        deltas[1] = deltaY;
+
+        pool.reserves[0] += deltaX;
+        pool.reserves[1] += deltaY;
+
+        invariant = tradingFunction(
+            pool.reserves,
+            pool.totalLiquidity + deltaLiquidity,
+            getPoolParams(poolId)
+        );
+
+        valid = invariant >= 0;
+    }
+
+    function validateDeallocate(
+        address,
+        uint256 poolId,
+        Pool memory pool,
+        bytes calldata data
+    )
+        external
+        view
+        override
+        returns (
+            bool valid,
+            int256 invariant,
+            uint256[] memory deltas,
+            uint256 deltaLiquidity
+        )
+    {
+        (uint256 deltaX, uint256 deltaY, uint256 maxDeltaL) =
+            abi.decode(data, (uint256, uint256, uint256));
+
+        deltaLiquidity =
+            computeDeltaLiquidity(deltaX, deltaY, internalParams[poolId].price);
+        if (maxDeltaL > deltaLiquidity) revert InvalidDeltaLiquidity();
+
+        deltas = new uint256[](2);
+        deltas[0] = deltaX;
+        deltas[1] = deltaY;
+
+        pool.reserves[0] -= deltaX;
+        pool.reserves[1] -= deltaY;
+
+        invariant = tradingFunction(
+            pool.reserves,
+            pool.totalLiquidity - deltaLiquidity,
+            getPoolParams(poolId)
+        );
+
+        valid = invariant >= 0;
+    }
+
     /// @inheritdoc IStrategy
     function update(
         address sender,
@@ -130,7 +213,7 @@ contract ConstantSum is PairStrategy {
         Pool memory,
         bytes memory
     ) internal pure override returns (uint256[] memory) {
-        return new uint256[](0);
+        return new uint256[](2);
     }
 
     /// @inheritdoc PairStrategy
@@ -139,6 +222,6 @@ contract ConstantSum is PairStrategy {
         Pool memory,
         bytes memory
     ) internal pure override returns (uint256[] memory) {
-        return new uint256[](0);
+        return new uint256[](2);
     }
 }

src/ConstantSum/ConstantSumMath.sol

@@ -13,8 +13,10 @@ function computeTradingFunction(
     uint256 totalLiquidity,
     uint256 price
 ) pure returns (int256) {
-    return int256(reserves[0].divWadUp(totalLiquidity))
-        + int256(reserves[1].divWadUp(totalLiquidity.mulWadUp(price))) - int256(ONE);
+    return int256(
+        price.mulWadUp(reserves[0].divWadUp(totalLiquidity))
+            + reserves[1].divWadUp(totalLiquidity)
+    ) - int256(ONE);
 }
 
 function computeInitialPoolData(
@@ -24,77 +26,17 @@ function computeInitialPoolData(
 ) pure returns (bytes memory) {
     // The pool can be initialized with any non-negative amount of rx, and ry.
     // so we have to allow a user to pass an amount of both even if one is zero.
-    uint256 L = rx + ry.divWadUp(params.price);
+    uint256 L = rx.mulWadDown(params.price) + ry;
     uint256[] memory reserves = new uint256[](2);
     reserves[0] = rx;
     reserves[1] = ry;
     return abi.encode(reserves, L, params);
 }
 
-function computeDeallocateGivenDeltaX(
+function computeDeltaLiquidity(
     uint256 deltaX,
-    uint256 rX,
-    uint256 rY,
-    uint256 totalLiquidity
-) pure returns (uint256 deltaY, uint256 deltaL) {
-    uint256 a = deltaX.divWadDown(rX);
-    if (rY > 0) {
-        deltaY = a.mulWadDown(rY);
-    }
-    deltaL = a.mulWadDown(totalLiquidity);
-}
-
-function computeDeallocateGivenDeltaY(
-    uint256 deltaY,
-    uint256 rX,
-    uint256 rY,
-    uint256 totalLiquidity
-) pure returns (uint256 deltaX, uint256 deltaL) {
-    uint256 a = deltaY.divWadDown(rY);
-    if (rX > 0) {
-        deltaX = a.mulWadDown(rX);
-    }
-    deltaL = a.mulWadDown(totalLiquidity);
-}
-
-function computeAllocateGivenDeltaX(
-    uint256 deltaX,
-    uint256 rX,
-    uint256 rY,
-    uint256 totalLiquidity
-) pure returns (uint256 deltaY, uint256 deltaL) {
-    uint256 a = deltaX.divWadUp(rX);
-    if (rY > 0) {
-        deltaY = a.mulWadUp(rY);
-    }
-    deltaL = a.mulWadUp(totalLiquidity);
-}
-
-function computeAllocateGivenDeltaY(
     uint256 deltaY,
-    uint256 rX,
-    uint256 rY,
-    uint256 totalLiquidity
-) pure returns (uint256 deltaX, uint256 deltaL) {
-    uint256 a = deltaY.divWadUp(rY);
-    if (rX > 0) {
-        deltaX = a.mulWadUp(rX);
-    }
-    deltaL = a.mulWadUp(totalLiquidity);
-}
-
-function computeDeltaGivenDeltaLRoundUp(
-    uint256 reserve,
-    uint256 deltaLiquidity,
-    uint256 totalLiquidity
-) pure returns (uint256) {
-    return reserve.mulWadUp(deltaLiquidity.divWadUp(totalLiquidity));
-}
-
-function computeDeltaGivenDeltaLRoundDown(
-    uint256 reserve,
-    uint256 deltaLiquidity,
-    uint256 totalLiquidity
+    uint256 price
 ) pure returns (uint256) {
-    return reserve.mulWadDown(deltaLiquidity.divWadDown(totalLiquidity));
+    return price.mulWadUp(deltaX) + deltaY;
 }