`test_strptime` fails when `time.strftime` does not support `%Z` format string

[CharlieZhao95]

Bug report

Bug description:

As time.strftime doc says:

%Z: Time zone name (no characters if no time zone exists). Deprecated.

Some C libraries may replace %Z with a null character, which may cause test_strptime.CalculationTests to fail. For example:

ERROR: test_day_of_week_calculation (test.test_strptime.CalculationTests.test_day_of_week_calculation)
--
Traceback (most recent call last):
  File "/data/ci/python3.12/lib/python3.12/test/test_strptime.py", line 563, in test_day_of_week_calculation
    result = _strptime._strptime_time(time.strftime(format_string, self.time_tuple),
             ^^
  File "/data/ci/python3.12/lib/python3.12/_strptime.py", line 548, in _strptime_time
    tt = _strptime(data_string, format)[0]
         ^^
  File "/data/ci/python3.12/lib/python3.12/_strptime.py", line 333, in _strptime
    raise ValueError("time data %r does not match format %r" %
ValueError: time data '2024 07 11 02 08 193 ' does not match format '%Y %m %d %H %S %j %Z'

In my opinion, removing the deprecated %Z from format_string variable will not affect those tests.

Similar tests that may fail:
test_strptime.CalculationTests.test_day_of_week_calculation
test_strptime.CalculationTests.test_gregorian_calculation
test_strptime.CalculationTests.test_julian_calculation
test_time.TimeTestCase.test_strptime

CPython versions tested on:

3.12

Operating systems tested on:

Linux

Linked PRs

• gh-121782: Remove deprecated %Z directive in strftime-related tests #135200

[encukou]

@CharlieZhao95, do you remember which C library this was?
We can't easily fix this without a reproducer.

[CharlieZhao95]

@CharlieZhao95, do you remember which C library this was? We can't easily fix this without a reproducer.

Thanks for the reminder, I missed the last message :)

I was working on a new unix-like embedded OS that uses musllibc. Now I think this case is more related to OS, maybe DST information is missing on the OS caused this error. And this is stated in the doc, I'm not sure if we should fix it.

See also:

musllibc strftime %Z

    case 'Z':
        if (tm->tm_isdst < 0) {
            *l = 0;
            return "";
        }
        fmt = __tm_to_tzname(tm);
        goto string;
...

[encukou]

A new OS! Exciting ❤️

But, on a new OS, you will generally need to skip a few tests, or patch things here and there.
If you really want to, send a PR and we could merge it. It shouldn't break supported platforms, shouldn't make the test ineffective, and should be very simple. Ideally it would help other OSes as well.

I'll close the issue—remove it from CPython's TODO list. We can reopen if you send a PR.