def test_find_max_value():
    tree = BinarySearchTree()
    tree.add(10)
    tree.add(5)
    tree.add(3)
    tree.add(7)
    tree.add(15)
    tree.add(11)

    assert tree.find_max_value() == 15
def test_find_max_value_empty_tree():
    tree = BinarySearchTree()

    assert tree.find_max_value() == None
def test_find_max_value_one_node_tree():
    tree = BinarySearchTree()
    tree.add(10)

    assert tree.find_max_value() == 10