py.test logging control

Question

We have recently switched to py.test for python testing (which is fantastic btw). However, I'm trying to figure out how to control the log output (i.e. the built-in python logging module). We have pytest-capturelog installed and this works as expected and when we want to see logs we can pass --nologcapture option.

However, how do you control the logging level (e.g. info, debug etc.) and also filter the logging (if you're only interested in a specific module). Is there existing plugins for py.test to achieve this or do we need to roll our own?

Thanks, Jonny

pytest-capturelog appears to have been replaced by https://pypi.python.org/pypi/pytest-catchlog/ This is mentioned in a number of comments below, but I initially missed this information and attempted to use pytest-capturelog. I'm leaving this comment hoping it'll be more visible and save the next guy from making my mistake. — cledoux, Jun 06 '17 at 20:54
Since version 3.3, `pytest-catchlog` is included in the `pytest` framework, so you don't need anything in addition. See [Logging](https://docs.pytest.org/en/latest/logging.html) section in the docs. — hoefling, Aug 02 '18 at 10:30

score 10 · Answer 1 · answered Aug 09 '12 at 06:34

10

Installing and using the pytest-capturelog plugin could satisfy most of your pytest/logging needs. If something is missing you should be able to implement it relatively easily.

answered Aug 09 '12 at 06:34

hpk42

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I just tried this with pytest 3.0.6. it worked fine but barks a lot: /pytest_capturelog.py:171 'pytest_runtest_makereport' hook uses deprecated __multicall__ argument WC1 None pytest_funcarg__caplog: declaring fixtures using "pytest_funcarg__" prefix is deprecated and scheduled to be removed in pytest 4.0. Please remove the prefix and use the @pytest.fixture decorator instead. ... – moin moin Feb 17 '17 at 08:57
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Looks like there is a fork that fixes this issue: https://pypi.python.org/pypi/pytest-catchlog/ – Danilo Bargen Mar 03 '17 at 10:40
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You don't need any plugins for that, because all this plugins are deprecated and `the functionality of this plugin has been merged to the pytest core` as said here https://github.com/eisensheng/pytest-catchlog (Fork of `pytest-capturelog`) – lucidyan Nov 13 '18 at 15:23

score 10 · Answer 2 · answered May 20 '14 at 19:25

10

As Holger said you can use pytest-capturelog:

def test_foo(caplog):
    caplog.setLevel(logging.INFO)
    pass

If you don't want to use pytest-capturelog you can use a stdout StreamHandler in your logging config so pytest will capture the log output. Here is an example basicConfig

logging.basicConfig(level=logging.DEBUG, stream=sys.stdout)

answered May 20 '14 at 19:25

Aron Curzon

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pytest-capturelog seems unmaintained and throws warnings. Looks like there is a fork that fixes this issue: https://pypi.python.org/pypi/pytest-catchlog/ – Danilo Bargen Mar 03 '17 at 10:40
@DaniloBargen *pytest* has integrated logging features as replacement of `pytest-capturelog` from version 3.3, as mentionned here: https://docs.pytest.org/en/latest/logging.html#release-notes – Jean-Francois T. Feb 14 '19 at 06:34
Hi, thanks for the hint. One remark: actually the method is called ```caplog.set_level(logging.INFO)``` (snake case). See: https://docs.pytest.org/en/6.2.x/logging.html#caplog-fixture – andi0815 Jan 31 '22 at 15:16

score 8 · Answer 3 · answered Aug 08 '16 at 16:08

A bit of a late contribution, but I can recommend pytest-logging for a simple drop-in logging capture solution. After pip install pytest-logging you can control the verbosity of the your logs (displayed on screen) with

$ py.test -s -v tests/your_test.py
$ py.test -s -vv tests/your_test.py
$ py.test -s -vvvv tests/your_test.py

etc... NB - the -s flag is important, without it py.test will filter out all the sys.stderr information.

score 6 · Answer 4 · answered Jan 20 '19 at 21:50

Pytest now has native support for logging control via the caplog fixture; no need for plugins.

You can specify the logging level for a particular logger or by default for the root logger:

import pytest

def test_bar(caplog):
    caplog.set_level(logging.CRITICAL, logger='root.baz')

Pytest also captures log output in caplog.records so you can assert logged levels and messages. For further information see the official documentation here and here.

aurzenligl · Answer 5 · 2016-12-04T22:53:37.547

A bit of an even later contribution: you can try pytest-logger. Novelty of this plugin is logging to filesystem: pytest provides nodeid for each test item, which can be used to organize test session logs directory (with help of pytest tmpdir facility and it's testcase begin/end hooks).

You can configure multiple handlers (with levels) for terminal and filesystem separately and provide own cmdline options for filtering loggers/levels to make it work for your specific test environment - e.g. by default you can log all to filesystem and small fraction to terminal, which can be changed on per-session basis with --log option if needed. Plugin does nothing by default, if user defines no hooks.

py.test logging control

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