def test_rotate_moves_front_element_to_back_of_queue(self):
q = CircularQueue()
second_element = CircularQueue._Node('bar', None)
first_element = CircularQueue._Node('foo', None)
q._tail = second_element
q._tail._next = first_element
q._size = 2
expected_result = 'foo'
q.rotate()
result = q._tail._element
self.assertEqual(result, expected_result)
def test_dequeue_returns_and_removes_first_element_from_queue(self):
q = CircularQueue()
second_element = CircularQueue._Node('bar', None)
first_element = CircularQueue._Node('foo', None)
q._tail = second_element
q._tail._next = first_element
q._size = 2
expected_result = 'foo'
result = q.dequeue()
self.assertEqual(q._size, 1)
self.assertEqual(result, expected_result)
self.assertIsNot(q._tail._next, first_element)
def test_enqueue_adds_an_element_to_the_back_of_queue(self):
q = CircularQueue()
first_element = CircularQueue._Node('foo', None)
first_element._next = first_element
q._tail = first_element
q._size = 1
second_element = 'bar'
q.enqueue(second_element)
result = q._tail._element
self.assertEqual(result, second_element)
def test_first_returns_first_element_without_removing_it(self):
q = CircularQueue()
newest = CircularQueue._Node('foo', None)
newest._next = newest
q._tail = newest
q._size = 1
expected_result = 'foo'
result = q.first()
self.assertEqual(result, expected_result)
self.assertIn(expected_result, q._tail._next._element)