def test_copy(self):
pairs = [('a', 1), ('b', 2), ('c', 3), ('d', 4)]
cache = LruCache(pairs)
self.assertEqual(cache.copy().items(), cache.items())
self.assertEqual(cache.copy().keys(), cache.keys())
self.assertEqual(LruCache().items(), LruCache().copy().items())
self.assertEqual(LruCache().keys(), LruCache().copy().keys())
