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Pytest 3.3: cannot mock root logger

See original GitHub issue

Pytest 3.3.0 uses the root logger in each test so it can no longer be mocked with monkeypatch

import logging
import pytest
from unittest.mock import MagicMock
@pytest.fixture
def setup(monkeypatch):
    mock = MagicMock()
    monkeypatch.setattr('logging.getLogger', lambda: mock) 
    return mock
def test_x(setup, monkeypatch):
    assert id(setup) == id(logging.getLogger())

raires

TypeError: <lambda>() takes 0 positional arguments but 1 was given
<python-path>\lib\contextlib.py:81: TypeError

changing the lambda to lambda _: mock raises

TypeError: '<' not supported between instances of 'int' and 'MagicMock'
<python-path>\lib\contextlib.py:81: TypeError

Moving the monkeypatch call in the function does not help since the second error is always raised. The error is raised in <python-path>\lib\site-packages\_pytest\logging.py on line 102 or 110

Using the --no-print-logs flag does not change the output

Pytest 3.2.5 does not have this problem

Also if there are subsequent tests after the one that caused the previous error, pytest crashes completely: appending

def test_y():
    assert True

after test_x in the example above results in the following error when running pytest without filters

x_test.py FE                                                             [100%]
INTERNALERROR> Traceback (most recent call last):
INTERNALERROR>   File "<python-path>\lib\site-packages\_pytest\main.py", line 103, in wrap_session
INTERNALERROR>     session.exitstatus = doit(config, session) or 0
INTERNALERROR>   File "<python-path>\lib\site-packages\_pytest\main.py", line 141, in _main
INTERNALERROR>     config.hook.pytest_runtestloop(session=session)
INTERNALERROR>   File "<python-path>\lib\site-packages\pluggy\__init__.py", line 617, in __call__
INTERNALERROR>     return self._hookexec(self, self._nonwrappers + self._wrappers, kwargs)
INTERNALERROR>   File "<python-path>\lib\site-packages\pluggy\__init__.py", line 222, in _hookexec
INTERNALERROR>     return self._inner_hookexec(hook, methods, kwargs)
INTERNALERROR>   File "<python-path>\lib\site-packages\pluggy\__init__.py", line 216, in <lambda>
INTERNALERROR>     firstresult=hook.spec_opts.get('firstresult'),
INTERNALERROR>   File "<python-path>\lib\site-packages\pluggy\callers.py", line 201, in _multicall
INTERNALERROR>     return outcome.get_result()
INTERNALERROR>   File "<python-path>\lib\site-packages\pluggy\callers.py", line 76, in get_result
INTERNALERROR>     raise ex[1].with_traceback(ex[2])
INTERNALERROR>   File "<python-path>\lib\site-packages\pluggy\callers.py", line 180, in _multicall
INTERNALERROR>     res = hook_impl.function(*args)
INTERNALERROR>   File "<python-path>\lib\site-packages\_pytest\main.py", line 164, in pytest_runtestloop
INTERNALERROR>     item.config.hook.pytest_runtest_protocol(item=item, nextitem=nextitem)
INTERNALERROR>   File "<python-path>\lib\site-packages\pluggy\__init__.py", line 617, in __call__
INTERNALERROR>     return self._hookexec(self, self._nonwrappers + self._wrappers, kwargs)
INTERNALERROR>   File "<python-path>\lib\site-packages\pluggy\__init__.py", line 222, in _hookexec
INTERNALERROR>     return self._inner_hookexec(hook, methods, kwargs)
INTERNALERROR>   File "<python-path>\lib\site-packages\pluggy\__init__.py", line 216, in <lambda>
INTERNALERROR>     firstresult=hook.spec_opts.get('firstresult'),
INTERNALERROR>   File "<python-path>\lib\site-packages\pluggy\callers.py", line 201, in _multicall
INTERNALERROR>     return outcome.get_result()
INTERNALERROR>   File "<python-path>\lib\site-packages\pluggy\callers.py", line 76, in get_result
INTERNALERROR>     raise ex[1].with_traceback(ex[2])
INTERNALERROR>   File "<python-path>\lib\site-packages\pluggy\callers.py", line 180, in _multicall
INTERNALERROR>     res = hook_impl.function(*args)
INTERNALERROR>   File "<python-path>\lib\site-packages\_pytest\runner.py", line 63, in pytest_runtest_protocol
INTERNALERROR>     runtestprotocol(item, nextitem=nextitem)
INTERNALERROR>   File "<python-path>\lib\site-packages\_pytest\runner.py", line 71, in runtestprotocol
INTERNALERROR>     rep = call_and_report(item, "setup", log)
INTERNALERROR>   File "<python-path>\lib\site-packages\_pytest\runner.py", line 159, in call_and_report
INTERNALERROR>     report = hook.pytest_runtest_makereport(item=item, call=call)
INTERNALERROR>   File "<python-path>\lib\site-packages\pluggy\__init__.py", line 617, in __call__
INTERNALERROR>     return self._hookexec(self, self._nonwrappers + self._wrappers, kwargs)
INTERNALERROR>   File "<python-path>\lib\site-packages\pluggy\__init__.py", line 222, in _hookexec
INTERNALERROR>     return self._inner_hookexec(hook, methods, kwargs)
INTERNALERROR>   File "<python-path>\lib\site-packages\pluggy\__init__.py", line 216, in <lambda>
INTERNALERROR>     firstresult=hook.spec_opts.get('firstresult'),
INTERNALERROR>   File "<python-path>\lib\site-packages\pluggy\callers.py", line 196, in _multicall
INTERNALERROR>     gen.send(outcome)
INTERNALERROR>   File "<python-path>\lib\site-packages\_pytest\skipping.py", line 264, in pytest_runtest_makereport
INTERNALERROR>     elif item._skipped_by_mark and rep.skipped and type(rep.longrepr) is tuple:
INTERNALERROR> AttributeError: 'Function' object has no attribute '_skipped_by_mark'

Selecting only test_x does not raises the AttributeError I’m on windows 10 with python 3.6.3, but I’ve confirmed the same bug on linux under python 3.5 and 3.6

Issue Analytics

State:
Created 6 years ago
Comments:12 (5 by maintainers)

Top GitHub Comments

3reactions

mikeneronecommented, Apr 5, 2018

BTW, you can still patch getLogger() in a fixture - just patch it with a function that only applies the patch for non-root loggers. As an extra precaution, I would also exclude loggers with “pytest” in the name. E.g.

@pytest.fixture(autouse=True)
def _always_patch_loggers(mocker):
    real_get_logger = logging.getLogger

    def get_patched_logger(name=None):
        logger = real_get_logger(name)
        if not isinstance(logger._log, mocker.Mock) and name and 'pytest' not in name:
            mocker.patch.object(logger, '_log')
        return logger

    mocker.patch.object(logging, 'getLogger', side_effect=get_patched_logger)

(Oh, and I’m using pytest-mock here - adapt if you want to use monkeypatch.)

1reaction

CaselITcommented, Mar 1, 2018

Yes, of course, it should take into consideration the flag -p no:logging. Again I’m not familiar at all with the internals of pytest, so it may be totally unfeasible doing what I suggested

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