What is the best way of setting limits of fuzz test input parameters in Foundry?

Question

Let's take an example, where we have a stake function, with the stake's endTimestamp in uin64.

function stake(uint256 amount, uin64 endTimestamp)

It is assumed endTimestamp should never be less than the timestamp at which the stake function was called. What is the best way of creating such a limit in a Foundry test?

Answer 1

Foundry implements function bound(uint256 x, uint256 min, uint256 max), which bounds a variable parameter to a certain range. To bound an input parameter, you can do something like this:

function stake(uint256 amount, uin64 endTimestamp) {
        endtimestamp = uint64(bound(endTimestamp, block.timestamp, type(uint64).max))
        _;
}

You can read more about it here: https://book.getfoundry.sh/reference/forge-std/bound