AssertionError has no attribute '__cause__'

[icemac]

The traceback below happened using Python 2.7.13 the AssertionError was caused by a normal assert statement those assertion was false.

Versions:
plugins: cov-2.4.0, flake8-0.8.1, remove-stale-bytecode-2.1, rerunfailures-2.1.0, sugar-0.8.0
pytest 3.0.7, Python 2.7.13 on Mac OS 10.12

INTERNALERROR> Traceback (most recent call last):
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/main.py", line 98, in wrap_session
INTERNALERROR>     session.exitstatus = doit(config, session) or 0
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/main.py", line 133, in _main
INTERNALERROR>     config.hook.pytest_runtestloop(session=session)
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/vendored_packages/pluggy.py", line 745, in __call__
INTERNALERROR>     return self._hookexec(self, self._nonwrappers + self._wrappers, kwargs)
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/vendored_packages/pluggy.py", line 339, in _hookexec
INTERNALERROR>     return self._inner_hookexec(hook, methods, kwargs)
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/vendored_packages/pluggy.py", line 334, in <lambda>
INTERNALERROR>     _MultiCall(methods, kwargs, hook.spec_opts).execute()
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/vendored_packages/pluggy.py", line 613, in execute
INTERNALERROR>     return _wrapped_call(hook_impl.function(*args), self.execute)
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/vendored_packages/pluggy.py", line 254, in _wrapped_call
INTERNALERROR>     return call_outcome.get_result()
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/vendored_packages/pluggy.py", line 280, in get_result
INTERNALERROR>     _reraise(*ex)  # noqa
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/vendored_packages/pluggy.py", line 265, in __init__
INTERNALERROR>     self.result = func()
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/vendored_packages/pluggy.py", line 614, in execute
INTERNALERROR>     res = hook_impl.function(*args)
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/main.py", line 154, in pytest_runtestloop
INTERNALERROR>     item.config.hook.pytest_runtest_protocol(item=item, nextitem=nextitem)
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/vendored_packages/pluggy.py", line 745, in __call__
INTERNALERROR>     return self._hookexec(self, self._nonwrappers + self._wrappers, kwargs)
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/vendored_packages/pluggy.py", line 339, in _hookexec
INTERNALERROR>     return self._inner_hookexec(hook, methods, kwargs)
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/vendored_packages/pluggy.py", line 334, in <lambda>
INTERNALERROR>     _MultiCall(methods, kwargs, hook.spec_opts).execute()
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/vendored_packages/pluggy.py", line 613, in execute
INTERNALERROR>     return _wrapped_call(hook_impl.function(*args), self.execute)
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/vendored_packages/pluggy.py", line 254, in _wrapped_call
INTERNALERROR>     return call_outcome.get_result()
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/vendored_packages/pluggy.py", line 280, in get_result
INTERNALERROR>     _reraise(*ex)  # noqa
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/vendored_packages/pluggy.py", line 265, in __init__
INTERNALERROR>     self.result = func()
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/vendored_packages/pluggy.py", line 614, in execute
INTERNALERROR>     res = hook_impl.function(*args)
INTERNALERROR>   File ".../eggs/pytest_rerunfailures-2.1.0-py2.7.egg/pytest_rerunfailures.py", line 75, in pytest_runtest_protocol
INTERNALERROR>     reports = runtestprotocol(item, nextitem=nextitem, log=False)
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/runner.py", line 79, in runtestprotocol
INTERNALERROR>     reports.append(call_and_report(item, "call", log))
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/runner.py", line 135, in call_and_report
INTERNALERROR>     report = hook.pytest_runtest_makereport(item=item, call=call)
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/vendored_packages/pluggy.py", line 745, in __call__
INTERNALERROR>     return self._hookexec(self, self._nonwrappers + self._wrappers, kwargs)
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/vendored_packages/pluggy.py", line 339, in _hookexec
INTERNALERROR>     return self._inner_hookexec(hook, methods, kwargs)
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/vendored_packages/pluggy.py", line 334, in <lambda>
INTERNALERROR>     _MultiCall(methods, kwargs, hook.spec_opts).execute()
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/vendored_packages/pluggy.py", line 613, in execute
INTERNALERROR>     return _wrapped_call(hook_impl.function(*args), self.execute)
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/vendored_packages/pluggy.py", line 250, in _wrapped_call
INTERNALERROR>     wrap_controller.send(call_outcome)
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/skipping.py", line 227, in pytest_runtest_makereport
INTERNALERROR>     rep = outcome.get_result()
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/vendored_packages/pluggy.py", line 280, in get_result
INTERNALERROR>     _reraise(*ex)  # noqa
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/vendored_packages/pluggy.py", line 265, in __init__
INTERNALERROR>     self.result = func()
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/vendored_packages/pluggy.py", line 614, in execute
INTERNALERROR>     res = hook_impl.function(*args)
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/runner.py", line 272, in pytest_runtest_makereport
INTERNALERROR>     longrepr = item.repr_failure(excinfo)
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/python.py", line 600, in repr_failure
INTERNALERROR>     return self._repr_failure_py(excinfo, style=style)
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/python.py", line 593, in _repr_failure_py
INTERNALERROR>     style=style)
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/main.py", line 449, in _repr_failure_py
INTERNALERROR>     style=style, tbfilter=tbfilter)
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/_code/code.py", line 427, in getrepr
INTERNALERROR>     return fmt.repr_excinfo(self)
INTERNALERROR>   File ".../eggs/pytest-3.0.7-py2.7.egg/_pytest/_code/code.py", line 640, in repr_excinfo
INTERNALERROR>     if e.__cause__ is not None:
INTERNALERROR> AttributeError: 'exceptions.AssertionError' object has no attribute '__cause__'

[RonnyPfannschmidt]

interesting, according to https://github.com/pytest-dev/pytest/blob/master/_pytest/_code/code.py#L620 this should not happen, care to elaborate on your environment?

[icemac]

@RonnyPfannschmidt In another test I call:

monkeypatch.setattr("sys.version_info", (3, 0, 0, 'final', 0))
assert ...

Where monkeypatch is the py.test monkeypatch fixture.
Could it be that this patch is not torn down correctly?

[RonnyPfannschmidt]

@icemac at first glance that seems unlikely, but there may be some merit to investigating this in detail,

its also a potential to restructure things, we shouldn't do such decisions at run-time at all

[nicoddemus]

The simplest fix is to check against _pytest.compat._PY2 instead of sys.version_info in https://github.com/pytest-dev/pytest/blob/master/_pytest/_code/code.py#L620.

This is in line with our general consensus that we should avoid relying on builtins at run-time (same deal with open during assertion rewrite for example).

[nicoddemus]

@icemac would you care to contribute a PR with that small fix?

[icemac]

@nicoddemus Okay.

[icemac]

Fix see #2359.