text: import unittest
  from queue import Queue
  
  
  class TestStack(unittest.TestCase):
      def test_enqueue(self):
          q = Queue()
          self.assertEqual(q.items, [])
          q.enqueue(1)
          self.assertEqual(q.items, [1])
          q.enqueue("fish")
          self.assertEqual(q.items, ["fish", 1])
  
      def test_dequeue(self):
          q = Queue()
          q.enqueue(1)
          q.enqueue("fish")
          self.assertEqual(q.items, ["fish", 1])
          self.assertEqual(q.dequeue(), 1)
          self.assertEqual(q.items, ["fish"])
  
      def test_dequeue_empty(self):
          q = Queue()
          self.assertEqual(q.dequeue(), None)
  
      def test_peek(self):
          q = Queue()
          q.enqueue(1)
          q.enqueue("fish")
          q.enqueue(2)
          self.assertEqual(q.items, [2, "fish", 1])
          self.assertEqual(q.peek(), 1)
  
      def test_peek_empty(self):
          q = Queue()
          self.assertEqual(q.peek(), None)
  
      def test_size(self):
          q = Queue()
          self.assertEqual(q.size(), 0)
          q.enqueue(1)
          self.assertEqual(q.size(), 1)
          q.enqueue("fish")
          self.assertEqual(q.size(), 2)
          q.enqueue(2)
          self.assertEqual(q.size(), 3)
  
      def test_is_empty(self):
          q = Queue()
          self.assertEqual(q.is_empty(), True)
          q.enqueue(1)
          self.assertEqual(q.is_empty(), False)
  
  
  if __name__ == "__main__":
      unittest.main(argv=["first-arg-is-ignored"], exit=False)
  