fix(katana-primitives): split_u256 (#1793)

fix split_u256

crates/katana/primitives/src/utils/mod.rs

@@ -9,7 +9,25 @@ pub mod transaction;
 /// The first element in the returned tuple is the low part, and the second element is the high
 /// part.
 pub fn split_u256(value: U256) -> (FieldElement, FieldElement) {
-    let low_u128: u128 = value.to::<u128>();
-    let high_u128: u128 = U256::from(value >> 128).to::<u128>();
+    let low_u128: u128 = (value & U256::from(u128::MAX)).to();
+    let high_u128: u128 = U256::from(value >> 128).to();
     (FieldElement::from(low_u128), FieldElement::from(high_u128))
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_split_u256() {
+        // Given
+        let value = U256::MAX;
+
+        // When
+        let (low, high) = split_u256(value);
+
+        // Then
+        assert_eq!(low, FieldElement::from(u128::MAX));
+        assert_eq!(high, FieldElement::from(u128::MAX));
+    }
+}