test_weakset.py 文件源码

def test_len_cycles(self):
        N = 20
        items = [RefCycle() for i in range(N)]
        s = WeakSet(items)
        del items
        it = iter(s)
        try:
            next(it)
        except StopIteration:
            pass
        gc.collect()
        n1 = len(s)
        del it
        gc.collect()
        n2 = len(s)
        # one item may be kept alive inside the iterator
        self.assertIn(n1, (0, 1))
        self.assertEqual(n2, 0)