ckb-merkle-mountain-range 0.3.0

A generalized merkle mountain range implementation
Documentation 
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use super::{MergeNumberHash, NumberHash};
use crate::{leaf_index_to_mmr_size, util::MemStore, Error, MMR};
use faster_hex::hex_string;
use proptest::prelude::*;
use rand::{seq::SliceRandom, thread_rng};

fn test_mmr(count: u32, proof_elem: Vec<u32>) {
    let store = MemStore::default();
    let mut mmr = MMR::<_, MergeNumberHash, _>::new(0, &store);
    let positions: Vec<u64> = (0u32..count)
        .map(|i| mmr.push(NumberHash::from(i)).unwrap())
        .collect();
    let root = mmr.get_root().expect("get root");
    let proof = mmr
        .gen_proof(
            proof_elem
                .iter()
                .map(|elem| positions[*elem as usize])
                .collect(),
        )
        .expect("gen proof");
    mmr.commit().expect("commit changes");
    let result = proof
        .verify(
            root,
            proof_elem
                .iter()
                .map(|elem| (positions[*elem as usize], NumberHash::from(*elem)))
                .collect(),
        )
        .unwrap();
    assert!(result);
}

fn test_gen_new_root_from_proof(count: u32) {
    let store = MemStore::default();
    let mut mmr = MMR::<_, MergeNumberHash, _>::new(0, &store);
    let positions: Vec<u64> = (0u32..count)
        .map(|i| mmr.push(NumberHash::from(i)).unwrap())
        .collect();
    let elem = count - 1;
    let pos = positions[elem as usize];
    let proof = mmr.gen_proof(vec![pos]).expect("gen proof");
    let new_elem = count;
    let new_pos = mmr.push(NumberHash::from(new_elem)).unwrap();
    let root = mmr.get_root().expect("get root");
    mmr.commit().expect("commit changes");
    let calculated_root = proof
        .calculate_root_with_new_leaf(
            vec![(pos, NumberHash::from(elem))],
            new_pos,
            NumberHash::from(new_elem),
            leaf_index_to_mmr_size(new_elem.into()),
        )
        .unwrap();
    assert_eq!(calculated_root, root);
}

#[test]
fn test_mmr_root() {
    let store = MemStore::default();
    let mut mmr = MMR::<_, MergeNumberHash, _>::new(0, &store);
    (0u32..11).for_each(|i| {
        mmr.push(NumberHash::from(i)).unwrap();
    });
    let root = mmr.get_root().expect("get root");
    let hex_root = hex_string(&root.0).unwrap();
    assert_eq!(
        "f6794677f37a57df6a5ec36ce61036e43a36c1a009d05c81c9aa685dde1fd6e3",
        hex_root
    );
}

#[test]
fn test_empty_mmr_root() {
    let store = MemStore::<NumberHash>::default();
    let mmr = MMR::<_, MergeNumberHash, _>::new(0, &store);
    assert_eq!(Err(Error::GetRootOnEmpty), mmr.get_root());
}

#[test]
fn test_mmr_3_peaks() {
    test_mmr(11, vec![5]);
}

#[test]
fn test_mmr_2_peaks() {
    test_mmr(10, vec![5]);
}

#[test]
fn test_mmr_1_peak() {
    test_mmr(8, vec![5]);
}

#[test]
fn test_mmr_first_elem_proof() {
    test_mmr(11, vec![0]);
}

#[test]
fn test_mmr_last_elem_proof() {
    test_mmr(11, vec![10]);
}

#[test]
fn test_mmr_1_elem() {
    test_mmr(1, vec![0]);
}

#[test]
fn test_mmr_2_elems() {
    test_mmr(2, vec![0]);
    test_mmr(2, vec![1]);
}

#[test]
fn test_mmr_2_leaves_merkle_proof() {
    test_mmr(11, vec![3, 7]);
    test_mmr(11, vec![3, 4]);
}

#[test]
fn test_mmr_2_sibling_leaves_merkle_proof() {
    test_mmr(11, vec![4, 5]);
    test_mmr(11, vec![5, 6]);
    test_mmr(11, vec![6, 7]);
}

#[test]
fn test_mmr_3_leaves_merkle_proof() {
    test_mmr(11, vec![4, 5, 6]);
    test_mmr(11, vec![3, 5, 7]);
    test_mmr(11, vec![3, 4, 5]);
    test_mmr(100, vec![3, 5, 13]);
}

#[test]
fn test_gen_root_from_proof() {
    test_gen_new_root_from_proof(11);
}

prop_compose! {
    fn count_elem(count: u32)
                (elem in 0..count)
                -> (u32, u32) {
                    (count, elem)
    }
}

proptest! {
    #[test]
    fn test_random_mmr(count in 10u32..500u32) {
        let mut leaves: Vec<u32> = (0..count).collect();
        let mut rng = thread_rng();
        leaves.shuffle(&mut rng);
        let leaves_count = rng.gen_range(1, count - 1);
        leaves.truncate(leaves_count as usize);
        test_mmr(count, leaves);
    }

    #[test]
    fn test_random_gen_root_with_new_leaf(count in 1u32..500u32) {
        test_gen_new_root_from_proof(count);
    }
}