def test_tree_max():
    bt = BinaryTree()
    bt.root = Node(6)
    bt.root.right = Node(5)
    bt.root.left = Node(-1)
    bt.root.right.left = Node(7)
    bt.root.left.left = Node(10)
    bt.root.right.right = Node(3)
    assert bt.findMaximumValue() == 10
def test_tree_max_empty():
    bt = BinaryTree()
    with pytest.raises(Exception):
        assert bt.findMaximumValue()