Description
Hello 👋
I am the maintainer of fuzzcheck, which is a fuzzing engine built for Rust.
For now, fuzzcheck works in the same way as cargo-fuzz in that one needs to create a fuzz folder, and then a fuzz target per test function. It is a bit cumbersome and I'd like to find a better solution. I really like the idea of auto-fuzz test, and I'd like to have something similar that works with fuzzcheck.
I am wondering whether it would be best to either:
- add support for fuzzcheck to auto-fuzz-test; or
- write similar functionality directly into fuzzcheck
I don't mind at all doing (2) by myself, but I thought it may be rude to do so without contacting you in the first place, since you may want (1) too, and in that case we should collaborate on it :)
There are a few important differences between fuzzcheck and cargo-fuzz that would make its integration a bit more difficult though. Whereas the fuzz targets of cargo-fuzz look like this:
// fuzz/fuzz_targets/target1.rs
libfuzzer_sys::fuzz_target!(|color: Rgb| {
my_library::test(color)
});The fuzz targets of fuzzcheck need to do a bit of setup to choose an appropriate Mutator and Serializer:
// fuzz/non_instrumented/fuzz_targets/target1.rs
// many `use` statements...
fn main() {
let mutator = Rgb::default_mutator();
let serializer = SerdeSerializer::default();
let _ = fuzzcheck::launch(my_library::test, mutator, serializer);
}While choosing default_mutator() and SerdeSerializer should be good for many cases, there should probably be an option to specify these two somewhere.
Another big difference between the two is that the arguments to a test function in fuzzcheck cannot be modified, even internally. So neither &mut T nor Cell<T> are allowed. If we have a function like:
fn foo(x: &mut Rgb) {
// ...
}Then the fuzz target should be:
fn test_foo(x: &Rgb) {
let mut x = x.clone();
foo(&mut x);
}There may be other problems, but these are the biggest ones I can think of right now.
Let me know if you'd like to work together to add support for fuzzcheck to auto-fuzz-test, or whether you would rather prefer to support only cargo-fuzz. But again, I really don't want to put any pressure on you to do anything :)