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IndexError if all post-cut traceback frames are hidden #13734

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#14025
Open
IndexError if all post-cut traceback frames are hidden#13734
#14025
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topic: tracebacksrelated to displaying and handling of tracebackstype: bugproblem that needs to be addressed
@cjwatson

Description

@cjwatson
cjwatson
opened on Sep 16, 2025

Following #13380, pytest-trio's tests fail with an IndexError when trying to display a traceback. Minimal reproducer with pytest 8.4.2 and pytest-trio 0.8.0 on Debian testing:

import pytest

@pytest.mark.trio
async def test_xfail():
    pytest.xfail()
pip list 
Package          Version
---------------- -----------
attrs            25.3.0
idna             3.10
iniconfig        2.1.0
outcome          1.3.0.post0
packaging        25.0
pip              25.2
pluggy           1.6.0
Pygments         2.19.2
pytest           8.4.2
pytest-trio      0.8.0
sniffio          1.3.1
sortedcontainers 2.4.0
trio             0.31.0
pytest output 
============================================================================= test session starts ==============================================================================
platform linux -- Python 3.13.7, pytest-8.4.2, pluggy-1.6.0
rootdir: /home/cjwatson
plugins: trio-0.8.0
collected 1 item

x.py
INTERNALERROR> Traceback (most recent call last):
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/_pytest/main.py", line 289, in wrap_session
INTERNALERROR>     session.exitstatus = doit(config, session) or 0
INTERNALERROR>                          ~~~~^^^^^^^^^^^^^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/_pytest/main.py", line 343, in _main
INTERNALERROR>     config.hook.pytest_runtestloop(session=session)
INTERNALERROR>     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/pluggy/_hooks.py", line 512, in __call__
INTERNALERROR>     return self._hookexec(self.name, self._hookimpls.copy(), kwargs, firstresult)
INTERNALERROR>            ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/pluggy/_manager.py", line 120, in _hookexec
INTERNALERROR>     return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
INTERNALERROR>            ~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/pluggy/_callers.py", line 167, in _multicall
INTERNALERROR>     raise exception
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/pluggy/_callers.py", line 139, in _multicall
INTERNALERROR>     teardown.throw(exception)
INTERNALERROR>     ~~~~~~~~~~~~~~^^^^^^^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/_pytest/logging.py", line 801, in pytest_runtestloop
INTERNALERROR>     return (yield)  # Run all the tests.
INTERNALERROR>             ^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/pluggy/_callers.py", line 139, in _multicall
INTERNALERROR>     teardown.throw(exception)
INTERNALERROR>     ~~~~~~~~~~~~~~^^^^^^^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/_pytest/terminal.py", line 688, in pytest_runtestloop
INTERNALERROR>     result = yield
INTERNALERROR>              ^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/pluggy/_callers.py", line 121, in _multicall
INTERNALERROR>     res = hook_impl.function(*args)
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/_pytest/main.py", line 367, in pytest_runtestloop
INTERNALERROR>     item.config.hook.pytest_runtest_protocol(item=item, nextitem=nextitem)
INTERNALERROR>     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/pluggy/_hooks.py", line 512, in __call__
INTERNALERROR>     return self._hookexec(self.name, self._hookimpls.copy(), kwargs, firstresult)
INTERNALERROR>            ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/pluggy/_manager.py", line 120, in _hookexec
INTERNALERROR>     return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
INTERNALERROR>            ~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/pluggy/_callers.py", line 167, in _multicall
INTERNALERROR>     raise exception
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/pluggy/_callers.py", line 139, in _multicall
INTERNALERROR>     teardown.throw(exception)
INTERNALERROR>     ~~~~~~~~~~~~~~^^^^^^^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/_pytest/warnings.py", line 90, in pytest_runtest_protocol
INTERNALERROR>     return (yield)
INTERNALERROR>             ^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/pluggy/_callers.py", line 139, in _multicall
INTERNALERROR>     teardown.throw(exception)
INTERNALERROR>     ~~~~~~~~~~~~~~^^^^^^^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/_pytest/assertion/__init__.py", line 192, in pytest_runtest_protocol
INTERNALERROR>     return (yield)
INTERNALERROR>             ^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/pluggy/_callers.py", line 139, in _multicall
INTERNALERROR>     teardown.throw(exception)
INTERNALERROR>     ~~~~~~~~~~~~~~^^^^^^^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/_pytest/unittest.py", line 475, in pytest_runtest_protocol
INTERNALERROR>     return (yield)
INTERNALERROR>             ^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/pluggy/_callers.py", line 139, in _multicall
INTERNALERROR>     teardown.throw(exception)
INTERNALERROR>     ~~~~~~~~~~~~~~^^^^^^^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/_pytest/faulthandler.py", line 88, in pytest_runtest_protocol
INTERNALERROR>     return (yield)
INTERNALERROR>             ^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/pluggy/_callers.py", line 121, in _multicall
INTERNALERROR>     res = hook_impl.function(*args)
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/_pytest/runner.py", line 117, in pytest_runtest_protocol
INTERNALERROR>     runtestprotocol(item, nextitem=nextitem)
INTERNALERROR>     ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/_pytest/runner.py", line 136, in runtestprotocol
INTERNALERROR>     reports.append(call_and_report(item, "call", log))
INTERNALERROR>                    ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/_pytest/runner.py", line 248, in call_and_report
INTERNALERROR>     report: TestReport = ihook.pytest_runtest_makereport(item=item, call=call)
INTERNALERROR>                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/pluggy/_hooks.py", line 512, in __call__
INTERNALERROR>     return self._hookexec(self.name, self._hookimpls.copy(), kwargs, firstresult)
INTERNALERROR>            ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/pluggy/_manager.py", line 120, in _hookexec
INTERNALERROR>     return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
INTERNALERROR>            ~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/pluggy/_callers.py", line 167, in _multicall
INTERNALERROR>     raise exception
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/pluggy/_callers.py", line 139, in _multicall
INTERNALERROR>     teardown.throw(exception)
INTERNALERROR>     ~~~~~~~~~~~~~~^^^^^^^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/_pytest/tmpdir.py", line 308, in pytest_runtest_makereport
INTERNALERROR>     rep = yield
INTERNALERROR>           ^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/pluggy/_callers.py", line 139, in _multicall
INTERNALERROR>     teardown.throw(exception)
INTERNALERROR>     ~~~~~~~~~~~~~~^^^^^^^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/_pytest/skipping.py", line 275, in pytest_runtest_makereport
INTERNALERROR>     rep = yield
INTERNALERROR>           ^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/pluggy/_callers.py", line 121, in _multicall
INTERNALERROR>     res = hook_impl.function(*args)
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/_pytest/runner.py", line 368, in pytest_runtest_makereport
INTERNALERROR>     return TestReport.from_item_and_call(item, call)
INTERNALERROR>            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/_pytest/reports.py", line 377, in from_item_and_call
INTERNALERROR>     longrepr = item.repr_failure(excinfo)
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/_pytest/python.py", line 1713, in repr_failure
INTERNALERROR>     return self._repr_failure_py(excinfo, style=style)
INTERNALERROR>            ~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/_pytest/nodes.py", line 456, in _repr_failure_py
INTERNALERROR>     return excinfo.getrepr(
INTERNALERROR>            ~~~~~~~~~~~~~~~^
INTERNALERROR>         funcargs=True,
INTERNALERROR>         ^^^^^^^^^^^^^^
INTERNALERROR>     ...<5 lines>...
INTERNALERROR>         truncate_args=truncate_args,
INTERNALERROR>         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
INTERNALERROR>     )
INTERNALERROR>     ^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/_pytest/_code/code.py", line 766, in getrepr
INTERNALERROR>     return fmt.repr_excinfo(self)
INTERNALERROR>            ~~~~~~~~~~~~~~~~^^^^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/_pytest/_code/code.py", line 1198, in repr_excinfo
INTERNALERROR>     traceback[0]._rawentry,
INTERNALERROR>     ~~~~~~~~~^^^
INTERNALERROR>   File "/home/cjwatson/pytest-env/lib/python3.13/site-packages/_pytest/_code/code.py", line 422, in __getitem__
INTERNALERROR>     return super().__getitem__(key)
INTERNALERROR>            ~~~~~~~~~~~~~~~~~~~^^^^^
INTERNALERROR> IndexError: list index out of range

I filed this as python-trio/pytest-trio#151 suggesting a fix there, but one of the pytest-trio maintainers said I should file an issue here and made a couple of suggestions. This is getting out of my league - could you have a look and see where this should best be fixed? Thanks!

  • a detailed description of the bug or problem you are having
  • output of pip list from the virtual environment you are using
  • pytest and operating system versions
  • minimal example if possible

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