Add fuzz tests to slice and splice

Author: ernestognw

test/utils/Bytes.t.sol

@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.20;
+
+import {Test} from "forge-std/Test.sol";
+import {Bytes} from "@openzeppelin/contracts/utils/Bytes.sol";
+
+contract BytesTest is Test {
+    using Bytes for bytes;
+
+    function testSliceWithStartOnly(bytes memory buffer, uint256 start) public pure {
+        start = bound(start, 0, buffer.length);
+        bytes memory result = buffer.slice(start);
+
+        // Should return bytes from start to end
+        assertEq(result.length, buffer.length - start);
+
+        // Verify content matches
+        for (uint256 i = 0; i < result.length; i++) {
+            assertEq(result[i], buffer[start + i]);
+        }
+
+        // Original buffer should remain unchanged
+        assertEq(buffer.length, buffer.length);
+        for (uint256 i = 0; i < buffer.length; i++) {
+            assertEq(buffer[i], buffer[i]);
+        }
+    }
+
+    function testSlice(bytes memory buffer, uint256 start, uint256 end) public pure {
+        bytes memory result = buffer.slice(start, end);
+
+        // Calculate expected bounds after sanitization
+        uint256 sanitizedEnd = end > buffer.length ? buffer.length : end;
+        uint256 sanitizedStart = start > sanitizedEnd ? sanitizedEnd : start;
+        uint256 expectedLength = sanitizedEnd - sanitizedStart;
+
+        assertEq(result.length, expectedLength);
+
+        // Verify content matches when there's content to verify
+        for (uint256 i = 0; i < result.length; i++) {
+            assertEq(result[i], buffer[sanitizedStart + i]);
+        }
+    }
+
+    function testSpliceWithStartOnly(bytes memory buffer, uint256 start) public pure {
+        start = bound(start, 0, buffer.length);
+        bytes memory originalBuffer = new bytes(buffer.length);
+        for (uint256 i = 0; i < buffer.length; i++) {
+            originalBuffer[i] = buffer[i];
+        }
+
+        bytes memory result = buffer.splice(start);
+
+        // Result should be the same object as input (modified in place)
+        assertEq(result.length == buffer.length, true);
+
+        // Should contain bytes from start to end, moved to beginning
+        assertEq(result.length, originalBuffer.length - start);
+
+        // Verify content matches moved content
+        for (uint256 i = 0; i < result.length; i++) {
+            assertEq(result[i], originalBuffer[start + i]);
+        }
+    }
+
+    function testSplice(bytes memory buffer, uint256 start, uint256 end) public pure {
+        bytes memory originalBuffer = new bytes(buffer.length);
+        for (uint256 i = 0; i < buffer.length; i++) {
+            originalBuffer[i] = buffer[i];
+        }
+
+        bytes memory result = buffer.splice(start, end);
+
+        // Calculate expected bounds after sanitization
+        uint256 sanitizedEnd = end > originalBuffer.length ? originalBuffer.length : end;
+        uint256 sanitizedStart = start > sanitizedEnd ? sanitizedEnd : start;
+        uint256 expectedLength = sanitizedEnd - sanitizedStart;
+
+        assertEq(result.length, expectedLength);
+
+        // Verify content matches moved content
+        for (uint256 i = 0; i < result.length; i++) {
+            assertEq(result[i], originalBuffer[sanitizedStart + i]);
+        }
+    }
+}