def test_push_one(self):
stack = ArrayStack()
stack.push(1)
self.assertEqual(stack.list(), [1])
self.assertEqual(stack.peek(), 1)
def test_peek_empty(self):
stack = ArrayStack()
with self.assertRaises(ValueError):
stack.peek()
def test_peek_non_empty(self):
stack = ArrayStack()
stack.push(1)
self.assertEqual(stack.peek(), 1)
def test_push_two(self):
stack = ArrayStack()
stack.push(1)
stack.push(2)
self.assertEqual(stack.list(), [1, 2])
self.assertEqual(stack.peek(), 2)
