Ignoring DeprectionWarning in pytest.warns

[lafrech]

The docs read:

By default, DeprecationWarning and PendingDeprecationWarning will not be caught when using pytest.warns() or recwarn because the default Python warnings filters hide them. If you wish to record them in your own code, use warnings.simplefilter('always').

It doesn't seem to be the case. My tests use pytest.warns to record warnings and DeprecationWarnings are recorded.

        with pytest.warns(None) as record:
            function_that_calls_a_lib_that_generates_a_deprecation_warning()
        assert not record

My understanding of this is limited. Could it be due to changes in Python 3.7 regarding DeprecationWarning?

Am I missing something?

The workaround I found for now is to filter the records afterwards, which is verbose and not elegant (managing PendingDeprecationWarning as well would be even longer).

        with pytest.warns(None) as record:
            function_that_calls_a_lib_that_generates_a_deprecation_warning()
        assert not [r for r in record if r.category is not DeprecationWarning]

---

Reproducible test case.

Using Python 3.7.3

import warnings

import pytest


def test_deprecation_warning():


    with pytest.warns(None) as record:
        warnings.warn("Test", DeprecationWarning)

    # This fails
    # assert not record

    print(record)
    # WarningsChecker(record=True)

    print([r.category for r in record])
    # [<class 'DeprecationWarning'>]

    # This succeeds
    assert not [r for r in record if r.category is not DeprecationWarning]

At some point, I thought it had something to do with the use of None in the call to warns but it doesn't:

import warnings

import pytest


def test_deprecation_warning():

    with pytest.warns(RuntimeWarning) as record:
        warnings.warn("Test", DeprecationWarning)
        warnings.warn("my warning", RuntimeWarning)

    print(record)
    # WarningsChecker(record=True)

    print([r.category for r in record])
    # [<class 'DeprecationWarning'>, <class 'RuntimeWarning'>]

[nicoddemus]

Hmmm strange. Do you have any warning filters active? Can you also provide a reproducible example?

[lafrech]

Sorry for the delay.

I added a test case. Fresh virtualenv with latest pytest, no filter. Python 3.7.3.

[nicoddemus]

Thanks and sorry about the delay.

Actually the docs are outdated, see #8754. 👍

Thanks a lot for bringing this to attention.

[lafrech]

Thanks for the update.

And for all the work on pytest.