def test_all_negatives():
tree = BinaryTree()
tree.add(-3)
tree.add(-4)
tree.add(-11)
tree.add(-5)
tree.add(-9)
assert tree.find_maximum_value() == -3
def test_max():
tree = BinaryTree()
tree.add(3)
tree.add(4)
tree.add(11)
tree.add(5)
tree.add(9)
assert tree.find_maximum_value() == 11
def test_find_maximum_on_left():
grok = BinaryTree()
groot = Node(12)
i = Node(9)
am = Node(5)
starlord = Node(3)
rocket = Node(7)
grok.root = i
grok.root.left = am
grok.root.right = starlord
grok.root.left.left = groot
grok.root.left.right = rocket
actual = grok.find_maximum_value()
assert actual == 12
def test_find_maxval_onenode_bt():
tree = BinaryTree(Node(-10))
expected = -10
actual = tree.find_maximum_value()
assert actual == expected
def test_find_maximum_value_empty():
hal = BinaryTree()
with pytest.raises(ValueError) as excinfo:
hal.find_maximum_value()
assert str(excinfo.value) == 'Cannot search an Empty BinaryTree'