[3.12] regrtest computes statistics (GH-108793)

[miss-islington]

test_netrc, test_pep646_syntax and test_xml_etree now return results
in the test_main() function.

Changes:

• Rewrite TestResult as a dataclass with a new State class.
• Add test.support.TestStats class and Regrtest.stats_dict attribute.
• libregrtest.runtest functions now modify a TestResult instance
  in-place.
• libregrtest summary lists the number of run tests and skipped
  tests, and denied resources.
• Add TestResult.has_meaningful_duration() method.
• Compute TestResult duration in the upper function.
• Use time.perf_counter() instead of time.monotonic().
• Regrtest: rename 'resource_denieds' attribute to 'resource_denied'.
• Rename CHILD_ERROR to MULTIPROCESSING_ERROR.
• Use match/case syntadx to have different code depending on the
  test state.

(cherry picked from commit d4e534c)

Co-authored-by: Victor Stinner vstinner@python.org
Co-authored-by: Alex Waygood Alex.Waygood@Gmail.com

[vstinner]

LGTM, good bot.

It can wait for Python 3.12.1.

[vstinner]

In general, I'm trying to keep libregrtest the same in all stable branches. It seems like 3.11 has an outdated libregrtest :-(

[vstinner]

In general, I'm trying to keep libregrtest the same in all stable branches. It seems like 3.11 has an outdated libregrtest :-(

I backported the statistics change to Python 3.11: #108820

I would prefer to have the same code in 3.11, 3.12 and main branches to ease future backports.

[Yhg1s]

Can you take a look at the test failures?

[vstinner]

Can you take a look at the test failures?

Oh. I missed the fact that the final changes uses the doctest.TestResults.skipped attribute which I just added to Python 3.13.

I close this broken backport PR and backported the change manually to Python 3.12 to adapt it to Python 3.12 API: PR #108833.