Test that fuzzes ordered arrays in Solidity

testFuzzOrderedArr.sol

// SPDX-License-Identifier: UNLICENSED
pragma solidity >=0.8.18;

import { Test } from "forge-std/Test.sol";
import { arange } from "solidity-generators/Generators.sol";

contract MyTest is Test {
    function testFuzz_OrderedArr(uint256[] memory arr) internal view {
        vm.assume(arr.length != 0);

        // Precompute the first element so that we don't bump into an underflow below.
        arr[0] = PREDEFINED_VALUE;

        // Return here if there's only one segment to not run into division by zero.
        uint256 len = arr.length;
        if (len == 1) {
            return;
        }

        // Generate `len` elements linearly spaced between `arr[0]` and max uint256.
        uint256 max = type(uint256).max;
        uint256 step = (max - arr[0]) / (len - 1);
        arr = arange(arr[0], max, step);

        // Fuzz the elements in a way that preserves their order in the array, using `bound`.
        uint40 halfStep = step / 2;
        for (uint256 i = 1; i < len; ++i) {
            arr[i] = bound(arr[i], arr[i] - halfStep, arr[i] + halfStep);
        }
    }
}