Backport Arbitrary support to 0.7.x and 0.6.x versions

[greyblake]

Backport Arbitrary support to 0.7.x and 0.6.x versions

[KodrAus]

Sorry for never replying on this one @greyblake, but it looks like rust-fuzz/arbitrary#33 did get resolved, so I'll go ahead and close this one. If you do still find yourself needing to backport this support though I would be happy to accept a PR for it.

[greyblake]

@KodrAus No worries, I know what it is to maintain an open source project.
Right, so I've added that ability to Arbitrary and luckily it was merged.

No we can workaround it with the following:

use uuid:uuid;
use arbitrary::Arbitrary;

#[derive(Arbitrary)]
struct User {
    #[arbitrary(with = arbitrary_uuid)]
    id: Uuid,
}

pub fn arbitrary_uuid(u: &mut Unstructured<'_>) -> arbitrary::Result<Uuid> {
    let bytes: [u8; 16] = u
        .bytes(16)?
        .try_into()
        .map_err(|_| arbitrary::Error::NotEnoughData)?;
    Uuid::from_bytes(&bytes).map_err(|_| arbitrary::Error::IncorrectFormat)
}

For the case if, let's say, the uuid is within a container (Option, Vec, HashMap, etc), one can use arbitrary_ext that helps to deal with that.

For example:

use uuid:uuid;
use arbitrary::Arbitrary;
use arbitrary_ext::{arbitrary_vec, arbitrary_option};

#[derive(Arbitrary)]
struct Group {
    #[arbitrary(with = arbitrary_option(arbitrary_uuid))]
    admin_id: Option<Uuid>,

    #[arbitrary(with = arbitrary_vec(arbitrary_uuid))]
    members_ids: Vec<Uuid>,
}

Of course, this can be helpful not only for old versions of UUID crate, but for other crates, which do not support arbitrary as well.