test: add test for root calculation & for mt state

tests/memory_keccak.rs

@@ -59,4 +59,39 @@ impl Hasher for MyKeccak {
 }
 
 #[test]
-fn insert_delete() {}
+fn insert_delete() {
+    let mut mt = MerkleTree::<MemoryDB, MyKeccak>::new(2, "abacaba");
+
+    assert_eq!(mt.capacity(), 4);
+    assert_eq!(mt.depth(), 2);
+
+    let leaves = [
+        hex!("0000000000000000000000000000000000000000000000000000000000000001"),
+        hex!("0000000000000000000000000000000000000000000000000000000000000002"),
+        hex!("0000000000000000000000000000000000000000000000000000000000000003"),
+        hex!("0000000000000000000000000000000000000000000000000000000000000004"),
+    ];
+
+    let default_tree_root =
+        hex!("b4c11951957c6f8f642c4af61cd6b24640fec6dc7fc607ee8206a99e92410d30");
+
+    assert_eq!(mt.root(), MyFr(default_tree_root));
+
+    let roots = [
+        hex!("c1ba1812ff680ce84c1d5b4f1087eeb08147a4d510f3496b2849df3a73f5af95"),
+        hex!("893760ec5b5bee236f29e85aef64f17139c3c1b7ff24ce64eb6315fca0f2485b"),
+        hex!("222ff5e0b5877792c2bc1670e2ccd0c2c97cd7bb1672a57d598db05092d3d72c"),
+        hex!("a9bb8c3f1f12e9aa903a50c47f314b57610a3ab32f2d463293f58836def38d36"),
+    ];
+
+    for i in 0..leaves.len() {
+        mt.insert(MyFr(leaves[i]));
+        assert_eq!(mt.root(), MyFr(roots[i]));
+    }
+
+    for i in (0..leaves.len()).rev() {
+        mt.delete(i);
+    }
+
+    assert_eq!(mt.root(), MyFr(default_tree_root));
+}