From 2ddb3556f0ee41955eb9efc2e4c7d2f87e5323df Mon Sep 17 00:00:00 2001
From: YoussefAboutika <aboutika.youssef@hotmail.com>
Date: Fri, 12 Sep 2025 23:45:06 +0200
Subject: [PATCH] Add approxEq function for approximate equality comparison

---
 foundry.lock           |  5 +++++
 src/Asserts.sol        |  4 ++++
 src/CryticAsserts.sol  | 22 ++++++++++++++++++++++
 src/FoundryAsserts.sol |  8 ++++++++
 src/HalmosAsserts.sol  |  8 ++++++++
 5 files changed, 47 insertions(+)
 create mode 100644 foundry.lock

diff --git a/foundry.lock b/foundry.lock
new file mode 100644
index 0000000..65b6e6a
--- /dev/null
+++ b/foundry.lock
@@ -0,0 +1,5 @@
+{
+  "lib/forge-std": {
+    "rev": "f73c73d2018eb6a111f35e4dae7b4f27401e9421"
+  }
+}
\ No newline at end of file
diff --git a/src/Asserts.sol b/src/Asserts.sol
index 7477660..709614f 100644
--- a/src/Asserts.sol
+++ b/src/Asserts.sol
@@ -12,6 +12,10 @@ abstract contract Asserts {
 
     function eq(uint256 a, uint256 b, string memory reason) internal virtual;
 
+    function approxEq(uint256 a, uint256 b, uint256 maxPercentDelta, string memory reason) internal virtual;
+
+    function approxEq(int256 a, int256 b, uint256 maxPercentDelta, string memory reason) internal virtual;
+
     function t(bool b, string memory reason) internal virtual;
 
     function between(uint256 value, uint256 low, uint256 high) internal virtual returns (uint256);
diff --git a/src/CryticAsserts.sol b/src/CryticAsserts.sol
index 76049e6..43bd450 100644
--- a/src/CryticAsserts.sol
+++ b/src/CryticAsserts.sol
@@ -41,6 +41,28 @@ contract CryticAsserts is Asserts {
         }
     }
 
+    function approxEq(uint256 a, uint256 b, uint256 maxPercentDelta, string memory message) internal virtual override {
+        if (b == 0) return eq(a, b, message); // If the right is 0, left must be too.
+
+        uint256 diff = a > b ? a - b : b - a;
+        uint256 percentDelta = diff * 1e18 / b;
+
+        gt(maxPercentDelta, percentDelta, message);
+    }
+
+    function approxEq(int256 a, int256 b, uint256 maxPercentDelta, string memory message) internal virtual override {
+        if (b == 0) return t(a == b, message); // If the right is 0, left must be too.
+
+        int256 d = a - b;
+        uint256 diff = d >= 0 ? uint256(d) : uint256(-d);
+        uint256 base = b >= 0 ? uint256(b) : uint256(-b);
+
+        // percentDelta = |a - b| / |b| in 1e18 precision
+        uint256 percentDelta = (diff * 1e18) / base;
+
+        gt(maxPercentDelta, percentDelta, message);
+    }
+
     function t(bool b, string memory reason) internal virtual override {
         if (!b) {
             emit Log(reason);
diff --git a/src/FoundryAsserts.sol b/src/FoundryAsserts.sol
index 2cdf57f..20f3dd0 100644
--- a/src/FoundryAsserts.sol
+++ b/src/FoundryAsserts.sol
@@ -24,6 +24,14 @@ contract FoundryAsserts is Test, Asserts {
     function eq(uint256 a, uint256 b, string memory reason) internal virtual override {
         assertEq(a, b, reason);
     }
+    
+    function approxEq(uint256 a, uint256 b, uint256 maxPercentDelta, string memory message) internal virtual override {
+        assertApproxEqRel(a, b, maxPercentDelta, message);
+    }
+
+    function approxEq(int256 a, int256 b, uint256 maxPercentDelta, string memory message) internal virtual override {
+        assertApproxEqRel(a, b, maxPercentDelta, message);
+    }
 
     function t(bool b, string memory reason) internal virtual override {
         assertTrue(b, reason);
diff --git a/src/HalmosAsserts.sol b/src/HalmosAsserts.sol
index 8ec3644..43e7552 100644
--- a/src/HalmosAsserts.sol
+++ b/src/HalmosAsserts.sol
@@ -25,6 +25,14 @@ contract HalmosAsserts is Test, Asserts {
         assertEq(a, b, reason);
     }
 
+    function approxEq(uint256 a, uint256 b, uint256 maxPercentDelta, string memory message) internal virtual override {
+        assertApproxEqRel(a, b, maxPercentDelta, message);
+    }
+
+    function approxEq(int256 a, int256 b, uint256 maxPercentDelta, string memory message) internal virtual override {
+        assertApproxEqRel(a, b, maxPercentDelta, message);
+    }
+    
     function t(bool b, string memory reason) internal virtual override {
         assertTrue(b, reason);
     }