Rework ChecksummedBytes internals to use a Range instead of a Bytes slice

[passaro]

Description of change

Preliminary refactor to prepare for adding integrity checks on the range itself. No changes in behavior.

Does this change impact existing behavior?

No.

---

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license and I agree to the terms of the Developer Certificate of Origin (DCO).

[dannycjones]

about there, just two minor things

[dannycjones]

I'd prefer we just include this setup inline in the test. We can simplify the code a bit too:

let buffer = Bytes::from_static([0; original.len()]);
let bytes = ChecksummedBytes::from_bytes(buffer);
let slice = bytes.slice(range);

[dannycjones]

better yet, we could just add (maybe test only) ChecksummedBytes::from_static?

impl ChecksummedBytes {
    pub const fn from_static(static_bytes: &'static [u8]) -> Self {
        let bytes = Bytes::from_static(static_bytes);
        ChecksummedBytes::from_bytes(bytes)
    }
}

test setup / 'boilerplate' becomes:

let bytes = ChecksummedBytes::from_static([0; original.len()]);
let slice = bytes.slice(range);

[passaro]

Your suggestion is missing the original range, but you are definitely right about the slice helper function not being clear!
In fact, I think the issue is that it is both setting up the instance to test and invoking the slice method on it. I've fixed that by using the helper function just for the setup and calling slice in each test function. I hope that it's clearer now.

[dannycjones]

thanks, yep clearer!

[dannycjones]

lgtm!