def test_stack_pop_multiple():
stack = Stack()
stack.push(1)
stack.push(2)
stack.push(3)
assert stack.pop() == 3
assert stack.pop() == 2
assert stack.pop() == 1
def test_stack_pop():
stack = Stack()
stack.push(1)
stack.push(2)
assert stack.pop() == 2
def test_pop_error():
stack = Stack()
with pytest.raises(AttributeError) as err:
assert stack.pop()
assert str(err.value) == 'The stack is empty'