Add -rW option to print captured warnings even for passing tests

[nicoddemus]

Follow up to #3621 (comment)

[nicoddemus]

#1232 can be used as basis to implement this.

[pytestbot]

GitMate.io thinks possibly related issues are #3251 (Warnings not captured during test collection), #1370 (Print out pytest-warnings?), #2178 (output capture broken when sys.stdout passed to print()), #1173 (Option to treat warnings as errors), and #2191 (add an option to warn about Python 3.x possible incompatibilities).

[jucaleb4]

Hi, can I help contribute to this one? @nicoddemus

[nicoddemus]

Sure @jucaleb4, please go ahead! 👍

[jucaleb4]

Awesome, thanks! I'll ask questions as they come along

[KamRon-67]

@nicoddemus has there been a solution merged? I am seeing seeing logic for the -rw option here https://github.com/pytest-dev/pytest/search?q=-rw&unscoped_q=-rw

[caramelomartins]

@KamRon-67 I think there's a subtlety here, which I'll try to convey properly.

Currently, -rW is implemented to report on warnings but it only displays those warnings on unsuccessful runs. What has been request in #3621 is for -rW to display those warnings even when runs are successful, such as rP does. I hope thos makes sense?

Anyone, please correct me if I understood this wrong.

[vbarbaresi]

I looked into this and I believe it doesn't apply anymore (partly due to PR #3931)
-rw option doesn't exist anymore, the CLI documentation says:

                      Warnings are displayed at all times except when
                        --disable-warnings is set
  --disable-warnings, --disable-pytest-warnings
                        disable warnings summary

A simple test shows that it works indeed, running pytest without any options gives you a warning summary

import warnings

def test_success():
    warnings.warn("hello")
    return True

In the example described in #3621 (comment), it's about an error inside a callback, not really a warning. I think it's the expected behavior: you wouldn't see the error running this code without pytest either.

[nicoddemus]

Indeed, thanks @vbarbaresi for reviewing this. 👍

Closing then.