def test_push(self):
stack = Stack()
stack.push(1)
self.assertEqual(stack.stack[0], 1)
stack.push(2)
self.assertEqual(stack.stack[0], 2)
def test_is_empty_is_true(self):
stack = Stack()
self.assertTrue(stack.is_empty())
def test_peek_is_not_empty(self):
stack = Stack()
stack.stack = ['bananas']
self.assertEqual('bananas', stack.peek())
def test_peek_is_empty(self):
stack = Stack()
self.assertIsNone(stack.peek())
def test_pop_not_empty(self):
stack = Stack()
stack.stack = [1, 2, 3]
self.assertEqual(1, stack.pop())
self.assertEqual(2, len(stack.stack))
def test_pop_empty(self):
stack = Stack()
self.assertIsNone(stack.pop())
def test_is_empty_is_false(self):
stack = Stack()
stack.stack = [1, 2, 3]
self.assertFalse(stack.is_empty())