def test_init(self):
stack = Stack()
self.assertEqual(stack.data, [])
stack = Stack(5)
self.assertEqual(stack.data, [5])
stack = Stack([1, 2, 3])
self.assertEqual(stack.data, [1, 2, 3])
def test_size(self):
stack = Stack()
self.assertEqual(stack.size(), 0)
stack.push(1)
self.assertEqual(stack.size(), 1)
stack.push(2)
self.assertEqual(stack.size(), 2)
def test_push(self):
stack = Stack()
stack.push(5)
self.assertEqual(stack.data, [5])
self.assertEqual(stack.size(), 1)
stack.push(5)
self.assertEqual(stack.data, [5, 5])
self.assertEqual(stack.size(), 2)
def test_peek(self):
stack = Stack()
self.assertRaises(Exception, stack.peek)
stack.push(5)
stack.push(4)
self.assertEqual(stack.peek(), 4)
self.assertEqual(stack.size(), 2)
stack.pop()
self.assertEqual(stack.peek(), 5)
self.assertEqual(stack.size(), 1)
def test_is_empty(self):
stack = Stack()
self.assertTrue(stack.is_empty())
stack.push(1)
self.assertFalse(stack.is_empty())
