subunit fails to build with Python 3.15.0a7.

SHELL_SHARE='./shell/share/' \
PYTHONPATH='/builddir/build/BUILD/subunit-1.4.5-build/subunit-1.4.5/python':'/builddir/build/BUILD/subunit-1.4.5-build/subunit-1.4.5':${PYTHONPATH} \
/usr/bin/python3 -m testtools.run all_tests.test_suite
Traceback (most recent call last):
  File "<frozen runpy>", line 196, in _run_module_as_main
  File "<frozen runpy>", line 87, in _run_code
  File "/usr/lib/python3.15/site-packages/testtools/run.py", line 339, in <module>
    main(sys.argv, sys.stdout)
    ~~~~^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.15/site-packages/testtools/run.py", line 333, in main
    TestProgram(
    ~~~~~~~~~~~^
        argv=argv, testRunner=partial(TestToolsTestRunner, stdout=stdout), stdout=stdout
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/usr/lib/python3.15/site-packages/testtools/run.py", line 223, in __init__
    self.parseArgs(argv)
    ~~~~~~~~~~~~~~^^^^^^
  File "/usr/lib64/python3.15/unittest/main.py", line 142, in parseArgs
    self.createTests()
    ~~~~~~~~~~~~~~~~^^
  File "/usr/lib64/python3.15/unittest/main.py", line 153, in createTests
    self.test = self.testLoader.loadTestsFromNames(self.testNames,
                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^
                                                   self.module)
                                                   ^^^^^^^^^^^^
  File "/usr/lib64/python3.15/unittest/loader.py", line 207, in loadTestsFromNames
    suites = [self.loadTestsFromName(name, module) for name in names]
              ~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^
  File "/usr/lib64/python3.15/unittest/loader.py", line 192, in loadTestsFromName
    test = obj()
  File "/builddir/build/BUILD/subunit-1.4.5-build/subunit-1.4.5/all_tests.py", line 32, in test_suite
    result.addTest(subunit.test_suite())
                   ~~~~~~~~~~~~~~~~~~^^
  File "/builddir/build/BUILD/subunit-1.4.5-build/subunit-1.4.5/python/subunit/__init__.py", line 179, in test_suite
    import subunit.tests
  File "/builddir/build/BUILD/subunit-1.4.5-build/subunit-1.4.5/python/subunit/tests/__init__.py", line 29, in <module>
    from subunit.tests import (  # noqa: E402
    ...<14 lines>...
    )
  File "/builddir/build/BUILD/subunit-1.4.5-build/subunit-1.4.5/python/subunit/tests/test_test_protocol2.py", line 33, in <module>
    from testtools.tests.test_testresult import TestStreamResultContract
ModuleNotFoundError: No module named 'testtools.tests.test_testresult'

https://docs.python.org/3.15/whatsnew/3.15.html

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.15/fedora-rawhide-x86_64/10222518-subunit/

For all our attempts to build subunit with Python 3.15, see:
https://copr.fedorainfracloud.org/coprs/g/python/python3.15/package/subunit/

Testing and mass rebuild of packages is happening in copr.
You can follow these instructions to test locally in mock if your package builds with Python 3.15:
https://copr.fedorainfracloud.org/coprs/g/python/python3.15/

Let us know here if you have any questions.

Python 3.15 is planned to be included in Fedora 45.
To make that update smoother, we're building Fedora packages with all pre-releases of Python 3.15.
A build failure prevents us from testing all dependent packages (transitive [Build]Requires),
so if this package is required a lot, it's important for us to get it fixed soon.

We'd appreciate help from the people who know this package best,
but if you don't want to work on this now, let us know so we can try to work around it on our side.