def test_max_with_changes():
stack = MaxStack()
stack.push(10)
stack.push(50)
stack.push(75)
stack.push(5)
assert stack.max() == 75
stack.pop()
stack.pop()
assert stack.max() == 50
def test_max_with_duplicates():
stack = MaxStack()
stack.push(10)
stack.push(50)
stack.push(50)
assert stack.max() == 50
stack.pop()
assert stack.max() == 50
stack.pop()
assert stack.max() == 10
def test_max():
stack = MaxStack()
stack.push(10)
stack.push(50)
stack.push(1)
assert stack.max() == 50
def test_max_no_items():
stack = MaxStack()
with pytest.raises(IndexError):
stack.max()