Pytest: Docs: API for pytest_collect_file

[pkch]

I'm not sure from reading the docs whether there is public API for pytest_collect_file that allows to fall back to the default collector. Would it be possible to clarify that?

Specifically, I need to use custom code to process certain (non-python) test files; I can recognize them by their path pattern. However, any other files should be processed using normal pytest rules. This would be very easy if I could (under custom-defined conditions) return the default collector from pytest_collect_file.

[RonnyPfannschmidt]

as far as i can tell all non-none results will be used,

while some hooks use the furst result, this one ises all results

[pkch]

Just to clarify this is the use case I'm talking about:

import _pytest
def pytest_collect_file(path, parent):
  ext = path.ext
  if ext == '.yaml':
    return YamlCollector(path=path, parent=parent)
  if ext == '.py':
    # here it's a regular .py file that should be handled by pytest the normal way
    return _pytest.python.pytest_collect_file(path, parent)

This works perfectly, but it uses non-public API by importing _pytest. It would be nice to show in the docs the proper way to do that, if it's available.

[pkch]

Oh wait... This works if I just to return None instead of _pytest.python.pytest_collect_file(path, parent). But how?

(The code snippet I posted above actually processes the .py files twice.)

[nicoddemus]

As @RonnyPfannschmidt mentioned, pytest will call pytest_collect_file for all plugins and use all collectors returned by them (ignoring None of course). So what happens is that you will return a collector for .yaml files and pytest's own builtin python plugin will return its own collector and things just work.

So in summary you really should only check for .yaml files and return your collector in that case:

def pytest_collect_file(path, parent):
  if path.ext == '.yaml':
    return YamlCollector(path=path, parent=parent)

Pytest will gather all collectors returned by all plugins because even a .py file might have tests depending on the plugin: doctests inside docstrings (doctest plugin) and test functions (python plugin).

That's what the example in https://docs.pytest.org/en/latest/example/nonpython.html does, btw.

[pkch]

I misunderstood @RonnyPfannschmidt comment, now it makes sense!

[pkch]

Should I make a PR to add basically your explanation to the docs, or is it good enough to have it here in this issue? And thanks =)

[nicoddemus]

A PR would be very welcome! 👍

[pkch]

Upon reading the docs more carefully, I realized that there's a very clear explanation here. The only thing I could add perhaps is to show the decorator firstresult=True above hooks that have that, do you think it would be useful?

[nicoddemus]

The only thing I could add perhaps is to show the decorator firstresult=True above hooks that have that, do you think it would be useful?

Definitely, thanks! You will need to add that information in the docstring of each hook in hookspec.py.