name : test_check_circular.py from unittest import TestCase import simplejson as json def default_iterable(obj): return list(obj) class TestCheckCircular(TestCase): def test_circular_dict(self): dct = {} dct['a'] = dct self.assertRaises(ValueError, json.dumps, dct) def test_circular_list(self): lst = [] lst.append(lst) self.assertRaises(ValueError, json.dumps, lst) def test_circular_composite(self): dct2 = {} dct2['a'] = [] dct2['a'].append(dct2) self.assertRaises(ValueError, json.dumps, dct2) def test_circular_default(self): json.dumps([set()], default=default_iterable) self.assertRaises(TypeError, json.dumps, [set()]) def test_circular_off_default(self): json.dumps([set()], default=default_iterable, check_circular=False) self.assertRaises(TypeError, json.dumps, [set()], check_circular=False)