From eca7d94322d51975970071bff0853b7474333852 Mon Sep 17 00:00:00 2001
From: Araz Abishov <araz@abishov.com>
Date: Sat, 21 Oct 2023 22:02:51 +0200
Subject: [PATCH] fix(core): fix split_off operation for RrbVec

---
 src/core/mod.rs |  3 +++
 tests/tests.rs  | 15 +++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/src/core/mod.rs b/src/core/mod.rs
index c2fdd21c0..33c3a81fc 100644
--- a/src/core/mod.rs
+++ b/src/core/mod.rs
@@ -345,6 +345,9 @@ impl<T: Clone + Debug> RrbVec<T> {
 
                         right.tail = new_tail;
                         right.tail_len = new_tail_len;
+
+                        // in case if tail is exactly BRANCH_FACTOR long, we should push it to the tree
+                        right.push_tail()
                     } else if right.tree.len() < BRANCH_FACTOR {
                         // root is leaf, but it is not fully dense
                         // hence, some of the values should be redistributed to the actual leaf
diff --git a/tests/tests.rs b/tests/tests.rs
index 469ca6f8b..156ba21d6 100644
--- a/tests/tests.rs
+++ b/tests/tests.rs
@@ -265,6 +265,21 @@ macro_rules! make_tests {
                 }
             }
 
+            #[test]
+            fn interleaving_push_split_off_push_operations() {
+                let mut vec_one = $vec::new();
+
+                for i in 0..(BRANCH_FACTOR * BRANCH_FACTOR) {
+                    vec_one.push(i);
+                }
+
+                let mut vec_two = vec_one.split_off(BRANCH_FACTOR * BRANCH_FACTOR - BRANCH_FACTOR);
+                vec_two.push(0xbeef);
+
+                assert_eq!(vec_one.len(), BRANCH_FACTOR * BRANCH_FACTOR - BRANCH_FACTOR);
+                assert_eq!(vec_two.len(), BRANCH_FACTOR + 1);
+            }
+
             #[test]
             fn interleaving_different_operations_must_maintain_correct_internal_state_for_var_sizes_4() {
                 interleaving_different_operations_must_maintain_correct_internal_state(4);