shardtree: Add proptest comparing insert_tree to batch_insert

shardtree/src/batch.rs

@@ -383,9 +383,15 @@ fn build_minimal_tree<H: Hashable + Clone + PartialEq>(
 #[cfg(test)]
 mod tests {
     use incrementalmerkletree::{Address, Level, Position, Retention};
+    use proptest::prelude::*;
 
     use super::{LocatedPrunableTree, RetentionFlags};
-    use crate::tree::tests::{leaf, nil, parent};
+    use crate::{
+        memory::MemoryShardStore,
+        testing::{arb_char_str, arb_leaves},
+        tree::tests::{leaf, nil, parent},
+        BatchInsertionResult, ShardTree,
+    };
 
     #[test]
     fn located_from_iter_non_sibling_adjacent() {
@@ -465,4 +471,41 @@ mod tests {
             .unwrap();
         assert_eq!(complete.subtree.right_filled_root(), Ok("abcd".to_string()));
     }
+
+    proptest! {
+        #[test]
+        fn batch_insert_matches_from_iter_and_insert_tree(
+            leaves in arb_leaves(arb_char_str())
+        ) {
+            const DEPTH: u8 = 6;
+            const SHARD_HEIGHT: u8 = 3;
+
+            let start = Position::from(0);
+            let end = start + leaves.len() as u64;
+
+            let BatchInsertionResult {
+                subtree,
+                mut remainder,
+                ..
+            } = LocatedPrunableTree::from_iter(start..end, 0.into(), leaves.clone().into_iter())
+                .unwrap();
+            assert_eq!(remainder.next(), None);
+
+            let subtree_addr = subtree.root_addr();
+            let root_from_iter = subtree.root().root_hash(subtree_addr, 0.into()).unwrap();
+
+            // Construct a tree using `ShardTree::insert_tree`.
+            let mut left =
+                ShardTree::<_, DEPTH, SHARD_HEIGHT>::new(MemoryShardStore::<_, usize>::empty(), 10);
+            left.insert_tree(subtree).unwrap();
+            assert_eq!(root_from_iter, left.root(subtree_addr, 0.into()).unwrap());
+
+            // Construct a tree using `ShardTree::batch_insert`.
+            let mut right = ShardTree::<_, DEPTH, SHARD_HEIGHT>::new(MemoryShardStore::empty(), 10);
+            right.batch_insert(start, leaves.into_iter()).unwrap();
+
+            // Check that the resulting trees are equal.
+            assert_eq!(left.root_at_checkpoint(0), right.root_at_checkpoint(0));
+        }
+    }
 }