diff --git a/test_avl.py b/test_avl.py
index 8b1970e..ba7388a 100644
--- a/test_avl.py
+++ b/test_avl.py
@@ -1,14 +1,42 @@
-from avl import AVLTree
+from avl import AVLTree, _balance_factor
+
+import logging
+import random
+from typing import List
 
 import hypothesis
 import hypothesis.strategies as st
-import logging
 import pytest
-import random
 
 logger = logging.getLogger(__name__)
 
 
+@pytest.mark.parametrize(
+    ("values", "expected_balance_factor"),
+    [
+        ([], 0),
+        ([1], 0),
+        ([1, -1], -1),
+        ([1, 2], 1),
+    ],
+)
+def test_balance_factor(
+    values: List[int], expected_balance_factor: int
+) -> None:
+    tree = AVLTree()
+    for v in values:
+        tree.insert(v)
+
+    assert _balance_factor(tree.root) == expected_balance_factor
+
+
+def test_incorrect_avl() -> None:
+    tree = AVLTree()
+    tree.insert(0)
+    tree.root.rank = 1
+    assert not tree.is_correct
+
+
 def test_empty() -> None:
     tree = AVLTree()
 
@@ -113,7 +141,7 @@ def _report(t_before: str, t_after: str) -> None:
         print(t_after, file=after)
 
 
-@hypothesis.settings(max_examples=100000, deadline=None)
+@hypothesis.settings(max_examples=1000, deadline=None)
 @hypothesis.given(config=delete_strategy())
 def test_delete_random(config):
     values, delete_order = config
diff --git a/test_wavl.py b/test_wavl.py
index 5d182f5..76c19dc 100644
--- a/test_wavl.py
+++ b/test_wavl.py
@@ -88,7 +88,7 @@ def test_rotate(values):
         assert tree.is_correct
 
 
-@hypothesis.settings(max_examples=1000, deadline=None)
+@hypothesis.settings(max_examples=10000, deadline=None)
 @hypothesis.given(values=st.sets(st.integers()))
 def test_insert_random(values):
     tree = WAVLTree()