def test_left_or_right_child_equal_value(self):
bt = BinaryTree()
bt.root = Node(4)
bt.root.left_child = Node(3)
bt.root.right_child = Node(7)
result = bt._left_or_right_child(bt.root, 4)
self.assertEqual(bt.root.right_child, result)
def test_left_or_right_child_no_larger_child(self):
bt = BinaryTree()
bt.root = Node(4)
bt.root.left_child = Node(3)
result = bt._left_or_right_child(bt.root, 5)
self.assertEqual(None, result)
def test_left_or_right_child_no_smaller_child(self):
bt = BinaryTree()
bt.root = Node(4)
bt.root.right_child = Node(7)
result = bt._left_or_right_child(bt.root, 2)
self.assertEqual(None, result)
