Fuzz Test Snapshotting Concept

[transmissions11]

Component

Forge

Describe the feature you would like

a cheatcode or config option that lets u specify a couple of specific inputs to snapshot for a fuzz test would be a repeatable and easy way to benchmark a fuzz tests' gas usage without introducing the variance that comes from mean/medians

here's what that could look like:

function testAdd(uint a, uint b) public {
    vm.snapshot(1, 2);
    vm.snapshot(10, 60);

    assertEq(a + b, b + a);
}

with a modifier it'd be really elegant:

modifier snapshot(uint256 a, uint256 b) {
    vm.snapshot(a, b)
}

function testAdd(uint a, uint b) public snapshot(1, 2) snapshot(10, 60) {
    assertEq(a + b, b + a);
}

could also use comment annotations but i know we dont rly like those

Additional context

related to my complaints in #1081

[d-xo]

related: #858

[transmissions11]

oh interesting @d-xo yeah seems like a lot of the functionality would be shared between them

[mds1]

In practice I think we'd have to do vm.snapshot(bytes memory) and ABI encode the params, cause there's basically infinite potential function signatures for fuzz tests

[transmissions11]

yup agreed, and can have a console.log style lib as an abstraction on top

[mds1]

@transmissions11 Is this worth keeping open? What is the use case for snapshotting only specific values, as opposed to concrete tests for some edge cases you may care about + deterministic seed with fuzz tests for the other cases?

[zerosnacks]

Closed by #7428, see: https://book.getfoundry.sh/forge/fuzz-testing#fuzz-test-fixtures