7.0.0 causes a new PytestDeprecationWarning in my plugin, but I'm not sure why...

[wimglenn]

I have a plugin, pytest-raisin, which allows using exception instances with pytest.raises. For example:

import pytest

def test_example():
    with pytest.raises(KeyError("x")):
        {}["x"]

Since pytest 7.0.0, there's a new warning:

$ python -m pytest
============================================================= test session starts ==============================================================
platform darwin -- Python 3.10.1, pytest-7.0.0, pluggy-1.0.0
rootdir: /private/tmp/b
plugins: raisin-0.3
collected 1 item                                                                                                                               

test_example.py .                                                                                                                        [100%]

=============================================================== warnings summary ===============================================================
test_example.py::test_example
  /private/tmp/b/.venv/lib/python3.10/site-packages/pytest_raisin.py:91: PytestDeprecationWarning: A private pytest class or function was used.
    self.excinfo.__init__(tp)

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
========================================================= 1 passed, 1 warning in 0.00s =========================================================

The line it indicates is here. I took care not to use anything with a leading underscore in the plugin implementation. I've been using this plugin all over the place and it's very handy I think, it would be a shame if it got broken in pytest 8. Actually I still have some hopes that the idea might get accepted into pytest itself (originally proposed in #4538).

Anything we could do either in pytest or in pytest-raisin to not trigger this warning? I had a look and #7469 seems related, specifically the part that says:

_pytest.python_api.RaisesContext - Not worth exposing, just a context manager.

[bluetech]

Hi @wimglenn,

You got it pretty much correctly - as part of formalizing pytest's public API, we audited ExceptionInfo and RaisesContext, and decided:

• Expose ExceptionInfo, but mark it's ctor private (so pytest is formally free to break how the type is constructed, but not any public methods/attributes).
• Don't expose RaisesContext.

My suggestion is to open an issue describing your use case for these, and we can make them public if it makes sense.

[wimglenn]

Thanks for the reply. Are all of ExceptionInfo's ctor private, or only the __init__? What about ExceptionInfo.for_later()?

[RonnyPfannschmidt]

ExceptionInfo is not a public api and I'd prefer if we had a opportunity to replace /remove it in future

[bluetech]

ExceptionInfo.for_later is public and documented which means that full stability is guaranteed for it, i.e. if we ever want to break it we will have to deprecate it first, and only remove in a major version.

[wimglenn]

In https://github.com/wimglenn/pytest-raisin/pull/7/files I've used ExceptionInfo.for_later() and the fill_unfilled method, hope that's OK. It made the warnings go away..

[bluetech]

Now you're only using public API so should be good!