RemovedInPytest4Warning via _pytest\compat.py:321

There are many RemovedInPytest4Warnings with pytest’s own tests, e.g.:

c:\projects\pytest\.tox\py36\lib\site-packages\_pytest\compat.py:321: RemovedInPytest4Warning: usage of Session.Class is deprecated, please use pytest.Class instead
360  return getattr(object, name, default)
361

(via https://ci.appveyor.com/project/pytestbot/pytest/builds/19474342/job/c83h5n8ne3snvf8o#L359)

Are those expected?

I would assume pytest should not causes warnings itself.

[nicoddemus]

Created #4236 to adjust the stack level.

[Zac-HD]

That only applies after pytest has finished the configure stage though, right? In the configure stage, _issue_config_warning downgrades warnings from errors to capturing them, even if we run with python -Werror -m pytest. IMO we should

• have a minimal dependency subset of the tests that we can run with Python-level warnings-as-errors
• issue a warning directly from _issue_config_warning if warnings have already been configured
• consider silencing warnings at the origin where we are using deprecated APIs for compatibility only

I’m poking at some of these now; I’ll update with results when I have some.

---

diff --git a/src/_pytest/warnings.py b/src/_pytest/warnings.py
index 6c4b921..e98d56a 100644
--- a/src/_pytest/warnings.py
+++ b/src/_pytest/warnings.py
@@ -165,8 +165,12 @@ def _issue_config_warning(warning, config):
     :param config:
     """
     with warnings.catch_warnings(record=True) as records:
-        warnings.simplefilter("always", type(warning))
+        # Set this warning to 'always', unless warnings have been configured
+        # at the interpreter level with e.g. -Werror or PYTHONWARNINGS=ignore
+        if sys.warnoptions:
+            warnings.simplefilter("always", type(warning))
         warnings.warn(warning, stacklevel=2)
-    config.hook.pytest_warning_captured.call_historic(
-        kwargs=dict(warning_message=records[0], when="config", item=None)
-    )
+    if records:
+        config.hook.pytest_warning_captured.call_historic(
+            kwargs=dict(warning_message=records[0], when="config", item=None)
+        )

Pretty sure this works but the setup to test it is awfully convoluted. I’ll leave it there for now before it turns into a serious un-fun slog.