def test_is_empty_when_pushed(self):
stack = ArrayStack()
stack.push(1)
self.assertFalse(stack.isEmpty())
def test_is_empty_when_pushed_and_deleted(self):
stack = ArrayStack()
stack.push(1)
stack.pop()
self.assertTrue(stack.isEmpty())
def test_is_empty_when_empty(self):
stack = ArrayStack()
self.assertTrue(stack.isEmpty())
