Init merkle-mountain-range

The MMR code is copy from https://github.com/nervosnetwork/ckb/pull/1598

src/tests/test_mmr.rs

@@ -0,0 +1,98 @@
+use super::{MergeNumberHash, NumberHash};
+use crate::{util::MemStore, Error, MMR};
+use faster_hex::hex_string;
+use proptest::prelude::*;
+
+fn test_mmr(count: u32, proof_elem: 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(positions[proof_elem as usize])
+        .expect("gen proof");
+    mmr.commit().expect("commit changes");
+    let result = proof
+        .verify(
+            root,
+            positions[proof_elem as usize],
+            NumberHash::from(proof_elem),
+        )
+        .unwrap();
+    assert!(result);
+}
+
+#[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, 5);
+}
+
+#[test]
+fn test_mmr_2_peaks() {
+    test_mmr(10, 5);
+}
+
+#[test]
+fn test_mmr_1_peak() {
+    test_mmr(8, 5);
+}
+
+#[test]
+fn test_mmr_first_elem_proof() {
+    test_mmr(11, 0);
+}
+
+#[test]
+fn test_mmr_last_elem_proof() {
+    test_mmr(11, 10);
+}
+
+#[test]
+fn test_mmr_1_elem() {
+    test_mmr(1, 0);
+}
+
+#[test]
+fn test_mmr_2_elems() {
+    test_mmr(2, 0);
+    test_mmr(2, 1);
+}
+
+prop_compose! {
+    fn count_elem(count: u32)
+                (elem in 0..count)
+                -> (u32, u32) {
+                    (count, elem)
+    }
+}
+
+proptest! {
+    #[test]
+    fn test_random_mmr((count , elem) in count_elem(500)) {
+        test_mmr(count, elem);
+    }
+}