def testDatabaseFixes(self):
        # Hack the pickle to make it refer to a timezone abbreviation
        # that does not match anything. The unpickler should be able
        # to repair this case
        tz = pytz.timezone('Australia/Melbourne')
        p = pickle.dumps(tz)
        tzname = tz._tzname
        hacked_p = p.replace(_byte_string(tzname), _byte_string('???'))
        self.assertNotEqual(p, hacked_p)
        unpickled_tz = pickle.loads(hacked_p)
        self.assertTrue(tz is unpickled_tz)

        # Simulate a database correction. In this case, the incorrect
        # data will continue to be used.
        p = pickle.dumps(tz)
        new_utcoffset = tz._utcoffset.seconds + 42

        # Python 3 introduced a new pickle protocol where numbers are stored in
        # hexadecimal representation. Here we extract the pickle
        # representation of the number for the current Python version.
        old_pickle_pattern = pickle.dumps(tz._utcoffset.seconds)[3:-1]
        new_pickle_pattern = pickle.dumps(new_utcoffset)[3:-1]
        hacked_p = p.replace(old_pickle_pattern, new_pickle_pattern)

        self.assertNotEqual(p, hacked_p)
        unpickled_tz = pickle.loads(hacked_p)
        self.assertEqual(unpickled_tz._utcoffset.seconds, new_utcoffset)
        self.assertTrue(tz is not unpickled_tz)

    def testOldPickles(self):
        # Ensure that applications serializing pytz instances as pickles
        # have no troubles upgrading to a new pytz release. These pickles
        # where created with pytz2006j
        east1 = pickle.loads(_byte_string(
            "cpytz\n_p\np1\n(S'US/Eastern'\np2\nI-18000\n"
            "I0\nS'EST'\np3\ntRp4\n."
            ))
        east2 = pytz.timezone('US/Eastern').localize(
            datetime(2006, 1, 1)).tzinfo
        self.assertTrue(east1 is east2)

        # Confirm changes in name munging between 2006j and 2007c cause
        # no problems.
        pap1 = pickle.loads(_byte_string(
            "cpytz\n_p\np1\n(S'America/Port_minus_au_minus_Prince'"
            "\np2\nI-17340\nI0\nS'PPMT'\np3\ntRp4\n."))
        pap2 = pytz.timezone('America/Port-au-Prince').localize(
            datetime(1910, 1, 1)).tzinfo
        self.assertTrue(pap1 is pap2)

        gmt1 = pickle.loads(_byte_string(
            "cpytz\n_p\np1\n(S'Etc/GMT_plus_10'\np2\ntRp3\n."))
        gmt2 = pytz.timezone('Etc/GMT+10')
        self.assertTrue(gmt1 is gmt2)