ab-blake3 0.1.0

use crate::{
    BLOCK_LEN, CHUNK_LEN, CVBytes, single_chunk_derive_key, single_chunk_hash,
    single_chunk_keyed_hash,
};
use blake3::{derive_key, hash, keyed_hash};

// Interesting input lengths to run tests on.
const TEST_CASES: &[usize] = &[
    0,
    1,
    2,
    3,
    4,
    5,
    6,
    7,
    8,
    BLOCK_LEN - 1,
    BLOCK_LEN,
    BLOCK_LEN + 1,
    2 * BLOCK_LEN - 1,
    2 * BLOCK_LEN,
    2 * BLOCK_LEN + 1,
    CHUNK_LEN - 1,
    CHUNK_LEN,
];

// There's a test to make sure these two are equal below.
const TEST_KEY: CVBytes = *b"whats the Elvish word for friend";

#[test]
fn test_compare_with_upstream() {
    let mut input_buf = [0; CHUNK_LEN];

    // Paint the input with a repeating byte pattern. We use a cycle length of 251,
    // because that's the largest prime number less than 256. This makes it
    // unlikely to swapping any two adjacent input blocks or chunks will give the
    // same answer.
    for (i, b) in input_buf.iter_mut().enumerate() {
        *b = (i % 251) as u8;
    }

    for &case in TEST_CASES {
        let input = &input_buf[..case];

        // regular
        assert_eq!(
            hash(input).as_bytes(),
            &single_chunk_hash(input).unwrap(),
            "{case}"
        );

        // keyed
        assert_eq!(
            keyed_hash(&TEST_KEY, input).as_bytes(),
            &single_chunk_keyed_hash(&TEST_KEY, input).unwrap(),
            "{case}"
        );

        // derive_key
        let context = "BLAKE3 2019-12-27 16:13:59 example context (not the test vector one)";
        assert_eq!(
            derive_key(context, input),
            single_chunk_derive_key(context, input).unwrap(),
            "{case}"
        );
    }
}