def test_deleting_only_node_should_leave_the_tree_empty():
object_under_test = RedBlackTree()
object_under_test.insert(22)
object_under_test.delete(22)
assert not object_under_test.traverse_preorder()
def test_deleting_nonexistent_value_should_raise():
object_under_test = RedBlackTree()
object_under_test.insert(44)
nonexistent_value = 22
with pytest.raises(ValueNotFoundInTreeError) as err:
object_under_test.delete(nonexistent_value)
assert f"{nonexistent_value}" in str(err)