AttributeError: 'DoctestItem' object has no attribute 'fixturenames'

[blueyed]

I think a common use case is to look at fixtures in pytest_collect_modifyitems:

def pytest_collection_modifyitems(config, items):
    for item in items:
        if "foo" in item.fixturenames:
…

But this crashes when doctests are involved:

  File "…/Vcs/pytest/src/_pytest/main.py", line 261, in pytest_collection
    return session.perform_collect()
  File "…/Vcs/pytest/src/_pytest/main.py", line 500, in perform_collect
    session=self, config=self.config, items=items
  File "…/Vcs/pluggy/pluggy/hooks.py", line 289, in __call__
    return self._hookexec(self, self.get_hookimpls(), kwargs)
  File "…/Vcs/pluggy/pluggy/manager.py", line 68, in _hookexec
    return self._inner_hookexec(hook, methods, kwargs)
  File "…/Vcs/pluggy/pluggy/manager.py", line 62, in <lambda>
    firstresult=hook.spec.opts.get("firstresult") if hook.spec else False,
  File "…/Vcs/pluggy/pluggy/callers.py", line 208, in _multicall
    return outcome.get_result()
  File "…/Vcs/pluggy/pluggy/callers.py", line 80, in get_result
    raise ex[1].with_traceback(ex[2])
  File "…/Vcs/pluggy/pluggy/callers.py", line 187, in _multicall
    res = hook_impl.function(*args)
  File "…/Vcs/pytest/testing/conftest.py", line 6, in pytest_collection_modifyitems
    for item in items:
AttributeError: 'DoctestItem' object has no attribute 'fixturenames'

This was fixed for --fixtures-per-test in #2789, but I think it would be better to just have an empty list there maybe?

[blueyed]

Any pointers in how to address this?
It's really unfortunate that every possible plugin has to handle/ignore that - especially since it might only happen then when using doctests (as within pytest's own tests).

I think it should be a given that items ins pytest_collection_modifyitems have an fixturenames attribute, no?

[RonnyPfannschmidt]

i believe it will happen to practically all item types that have no direct fixture system integration (aka 3rd party plugins as well, its really tricky to touch

[nicoddemus]

I think it should be a given that items ins pytest_collection_modifyitems have an fixturenames attribute, no?

Yeah as @RonnyPfannschmidt said, custom items which don't implement fixtures, while uncommon, are a definite possibility (besides Doctests, pytest-cpp also has custom items).

Unfortunately I don't have any idea on how to improve this situation.

Unless somebody has a suggestion, I think we should close this. :/

[blueyed]

What about a mixin / base class to have an empty list there?

[nicoddemus]

From a "pure" design POV it would not be nice, because items are generic and might be customizable. Fixtures are a feature only available on pytest.Function objects. On the other hand, from a practibility POV it might make sense.

But I lean towards the former, otherwise we now have this implicit contract that pytest.Item needs to support all methods/attributes a pytest.Function does.

I know it sucks and it trips some people, but down the road we might make things worse for ourselves if we have to guarantee that all items have a pytest.Function-like interface.