Test for 2CLP rounding fixes (#1195)

Co-authored-by: Juan Ignacio Ubeira <[email protected]>

pkg/pool-gyro/test/foundry/Gyro2CLPMathRounding.sol

@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+pragma solidity ^0.8.24;
+
+import "forge-std/Test.sol";
+
+import { Rounding } from "@balancer-labs/v3-interfaces/contracts/vault/VaultTypes.sol";
+
+import { ArrayHelpers } from "@balancer-labs/v3-solidity-utils/contracts/test/ArrayHelpers.sol";
+
+import "../../contracts/lib/Gyro2CLPMath.sol";
+
+struct QuadraticTerms {
+    uint256 a;
+    uint256 mb;
+    uint256 bSquare;
+    uint256 mc;
+}
+
+contract Gyro2CLPMathRoundingTest is Test {
+    using ArrayHelpers for *;
+
+    uint256 internal constant MIN_DIFF_ALPHA_BETA = 100;
+
+    uint256 internal constant MIN_SQRT_ALPHA = 0.01e18;
+    uint256 internal constant MAX_SQRT_ALPHA = 10e18 - MIN_DIFF_ALPHA_BETA;
+    // Make sqrtBeta 0.5% higher than sqrtAlpha
+    uint256 internal constant MIN_SQRT_BETA = MIN_SQRT_ALPHA;
+    uint256 internal constant MAX_SQRT_BETA = MAX_SQRT_ALPHA + MIN_DIFF_ALPHA_BETA;
+
+    function testCalculateQuadraticTermsRounding__Fuzz(
+        uint256[2] memory balances,
+        uint256 sqrtAlpha,
+        uint256 sqrtBeta
+    ) public pure {
+        balances[0] = bound(balances[0], 1e16, 1e8 * 1e18);
+        balances[1] = bound(balances[1], 1e16, 1e8 * 1e18);
+        sqrtAlpha = bound(sqrtAlpha, MIN_SQRT_ALPHA, MAX_SQRT_ALPHA);
+        sqrtBeta = bound(sqrtBeta, sqrtAlpha + MIN_DIFF_ALPHA_BETA, MAX_SQRT_BETA);
+
+        QuadraticTerms memory qTermsDown;
+        QuadraticTerms memory qTermsUp;
+
+        (qTermsDown.a, qTermsDown.mb, qTermsDown.bSquare, qTermsDown.mc) = Gyro2CLPMath.calculateQuadraticTerms(
+            balances.toMemoryArray(),
+            sqrtAlpha,
+            sqrtBeta,
+            Rounding.ROUND_DOWN
+        );
+        (qTermsUp.a, qTermsUp.mb, qTermsUp.bSquare, qTermsUp.mc) = Gyro2CLPMath.calculateQuadraticTerms(
+            balances.toMemoryArray(),
+            sqrtAlpha,
+            sqrtBeta,
+            Rounding.ROUND_UP
+        );
+
+        assertLe(qTermsUp.a, qTermsDown.a, "Wrong rounding result (a)");
+        assertGe(qTermsUp.mb, qTermsDown.mb, "Wrong rounding result (mb)");
+        assertGe(qTermsUp.bSquare, qTermsDown.bSquare, "Wrong rounding result (bSquare)");
+        assertGe(qTermsUp.mc, qTermsDown.mc, "Wrong rounding result (mc)");
+    }
+
+    function testCalculateQuadraticRounding__Fuzz(uint256 a, uint256 mb, uint256 mc) public pure {
+        a = bound(a, 1, 1e18); // 0 < a < FP(1)
+        mb = bound(mb, 1, 1e8 * 1e18);
+        uint256 bSquare = mb * mb; // This is an approximation just to unit fuzz calculate quadratic.
+        mc = bound(mc, 1, 1e8 * 1e18);
+
+        uint256 quadraticRoundDown = Gyro2CLPMath.calculateQuadratic(a, mb, bSquare, mc, Rounding.ROUND_DOWN);
+        uint256 quadraticRoundUp = Gyro2CLPMath.calculateQuadratic(a, mb, bSquare, mc, Rounding.ROUND_UP);
+
+        assertGe(quadraticRoundUp, quadraticRoundDown, "Wrong rounding result");
+    }
+
+    function testComputeInvariantRounding__Fuzz(
+        uint256[2] memory balances,
+        uint256 sqrtAlpha,
+        uint256 sqrtBeta
+    ) public pure {
+        balances[0] = bound(balances[0], 1e16, 1e8 * 1e18);
+        balances[1] = bound(balances[1], 1e16, 1e8 * 1e18);
+        sqrtAlpha = bound(sqrtAlpha, MIN_SQRT_ALPHA, MAX_SQRT_ALPHA);
+        sqrtBeta = bound(sqrtBeta, sqrtAlpha + MIN_DIFF_ALPHA_BETA, MAX_SQRT_BETA);
+
+        uint256 invariantDown = Gyro2CLPMath.calculateInvariant(
+            balances.toMemoryArray(),
+            sqrtAlpha,
+            sqrtBeta,
+            Rounding.ROUND_DOWN
+        );
+        uint256 invariantUp = Gyro2CLPMath.calculateInvariant(
+            balances.toMemoryArray(),
+            sqrtAlpha,
+            sqrtBeta,
+            Rounding.ROUND_UP
+        );
+
+        assertGe(invariantUp, invariantDown, "Wrong rounding result");
+    }
+}