def testMapsCompare(self):
    msg = map_unittest_pb2.TestMap()
    msg.map_int32_int32[-123] = -456
    self.assertEqual(msg.map_int32_int32, msg.map_int32_int32)
    self.assertEqual(msg.map_int32_foreign_message,
                     msg.map_int32_foreign_message)
    self.assertNotEqual(msg.map_int32_int32, 0)