def test_pop_until_empty(self):
ls = [randint(-10, 10) for _ in range(randint(1, 100))]
s = Stack(ls)
for i, e in enumerate(reversed(ls)):
elem = s.pop()
self.assertEqual(elem, e)
self.assertEqual(s.size, len(ls) - (i + 1))
self.assertTrue(s.is_empty())
def test_pop_last(self):
s = Stack([7])
self.assertEqual(s.pop(), 7)
self.assertTrue(s.is_empty())
self.assertEqual(s.size, 0)
def test_pop_empty_stack(self):
s = Stack()
self.assertIsNone(s.pop())