Heads up: Test testrunner-edge-cases.rst fails with Python 3.14.0a4

[befeleme]

(future) PROBLEM REPORT

What I did:

I tried to build zope.testrunner with Python 3.14.0a4 in Fedora Linux 43.
The test output is different than what's expected.

What I expect to happen:

Test pass

What actually happened:

+ /usr/bin/python3 -m tox --current-env -q --recreate -e py314
Running tests at level 1
Running zope.testrunner.layer.UnitTests tests:
  Set up zope.testrunner.layer.UnitTests in 0.000 seconds.
  Running:
.............

Failure in test /builddir/build/BUILD/python-zope-testrunner-6.6-build/BUILDROOT/usr/lib/python3.14/site-packages/zope/testrunner/tests/testrunner-edge-cases.rst
Failed doctest test for testrunner-edge-cases.rst
  File "/builddir/build/BUILD/python-zope-testrunner-6.6-build/BUILDROOT/usr/lib/python3.14/site-packages/zope/testrunner/tests/testrunner-edge-cases.rst", line 0

----------------------------------------------------------------------
File "/builddir/build/BUILD/python-zope-testrunner-6.6-build/BUILDROOT/usr/lib/python3.14/site-packages/zope/testrunner/tests/testrunner-edge-cases.rst", line 91, in testrunner-edge-cases.rst
Failed example:
    try: testrunner.run_internal(defaults)
    finally: sys.stdin = real_stdin
    # doctest: +ELLIPSIS
Differences (ndiff with -expected +actual):
    - Running zope.testrunner.layer.UnitTests tests:...
    ?                                               ---
    + Running zope.testrunner.layer.UnitTests tests:
    +   Set up zope.testrunner.layer.UnitTests in N.NNN seconds.
    - > testrunner-ex/sample3/sampletests_d.py(NNN)f()
    - -> ...
      (Pdb) p x
    - 1
      (Pdb) c
        Ran 1 tests with 0 failures, 0 errors and 0 skipped in N.NNN seconds.
    - ...
    + Tearing down left over layers:
    +   Tear down zope.testrunner.layer.UnitTests in N.NNN seconds.
      False

What version of Python and Zope/Addons I am using:

Fedora Linux 43, Python 3.14.0a4, zope.testrunner 6.6

[icemac]

This error is a bit strange.

The following change fixes it for all supported Python versions:

--- a/src/zope/testrunner/tests/testrunner-edge-cases.rst
+++ b/src/zope/testrunner/tests/testrunner-edge-cases.rst
@@ -92,7 +92,7 @@ Using pdb.set_trace in a function called by an ordinary test:
     ... finally: sys.stdin = real_stdin
     ... # doctest: +ELLIPSIS
     Running zope.testrunner.layer.UnitTests tests:...
-    > testrunner-ex/sample3/sampletests_d.py(47)f()
+    > ...testrunner-ex/sample3/sampletests_d.py(47)f()
     -> ...
     (Pdb) p x
     1

But only when the test is run in isolation like this:

$ tox -epy314 -- -t testrunner-edge-cases.rst

If it is run together with all the other tests it fails differently (I removed the assertion in the test file to make the diff easier to read.)

$ tox -epy314
...
File "/.../src/zope/testrunner/tests/testrunner-edge-cases.rst", line 91, in testrunner-edge-cases.rst
Failed example:
    try: testrunner.run_internal(defaults)
    finally: sys.stdin = real_stdin
    # doctest: +ELLIPSIS
Differences (ndiff with -expected +actual):
    + Running zope.testrunner.layer.UnitTests tests:
    +   Set up zope.testrunner.layer.UnitTests in 0.000 seconds.
    + (Pdb) p x
    + (Pdb) c
    +   Ran 1 tests with 0 failures, 0 errors and 0 skipped in 0.000 seconds.
    + Tearing down left over layers:
    +   Tear down zope.testrunner.layer.UnitTests in 0.000 seconds.
    + False

So all the output of pdb is missing.

This seems to be caused by testrunner-debugging.rst, if it runs before testrunner-edge-cases.rst the error shows up.

Running them in reverse order using:
$ tox -epy314 -- -t testrunner-edge-cases.rst -t testrunner-debugging.rst -cvv --shuffle --shuffle-seed=1

breaks testrunner-debugging.rst the same way: no pdb output rendered.

I am running out of time and steam here. So if someone wants to take over?