Question or problem about Python programming:
I would like to put some logging statements within test function to examine some state variables.
I have the following code snippet:
import pytest,os
import logging
logging.basicConfig(level=logging.DEBUG)
mylogger = logging.getLogger()
#############################################################################
def setup_module(module):
''' Setup for the entire module '''
mylogger.info('Inside Setup')
# Do the actual setup stuff here
pass
def setup_function(func):
''' Setup for test functions '''
if func == test_one:
mylogger.info(' Hurray !!')
def test_one():
''' Test One '''
mylogger.info('Inside Test 1')
#assert 0 == 1
pass
def test_two():
''' Test Two '''
mylogger.info('Inside Test 2')
pass
if __name__ == '__main__':
mylogger.info(' About to start the tests ')
pytest.main(args=[os.path.abspath(__file__)])
mylogger.info(' Done executing the tests ')
I get the following output:
[bmaryada-mbp:/Users/bmaryada/dev/platform/main/proto/tests/tpch $]python minitest.py INFO:root: About to start the tests ======================================================== test session starts ========================================================= platform darwin -- Python 2.6.2 -- pytest-2.0.0 collected 2 items minitest.py .. ====================================================== 2 passed in 0.01 seconds ====================================================== INFO:root: Done executing the tests
Notice that only the logging messages from the ‘__name__ == __main__’ block get transmitted to the console.
Is there a way to force pytest to emit logging to console from test methods as well?
How to solve the problem:
Solution 1:
Works for me, here’s the output I get: [snip -> example was incorrect]
Edit: It seems that you have to pass the -s option to py.test so it won’t capture stdout. Here (py.test not installed), it was enough to use python pytest.py -s pyt.py.
For your code, all you need is to pass -s in args to main:
pytest.main(args=['-s', os.path.abspath(__file__)])
See the py.test documentation on capturing output.
Solution 2:
Since version 3.3, pytest supports live logging, meaning that all the log records emitted in tests will be printed to the terminal immediately. The feature is documented under Live Logs section. Live logging is disabled by default; to enable it, set log_cli = 1 in the pytest.ini config1. Live logging supports emitting to terminal and file; the relevant options allow records customizing:
terminal:
log_cli_levellog_cli_formatlog_cli_date_format
file:
log_filelog_file_levellog_file_formatlog_file_date_format
Note: log_cli flag can’t be passed from command line and must be set in pytest.ini. All the other options can be both passed from command line or set in the config file.-o/--override option. So instead of declaring log_cli in pytest.ini, you can simply call:
$ pytest -o log_cli=true ...
Examples
Simple test file used for demonstrating:
# test_spam.py
import logging
LOGGER = logging.getLogger(__name__)
def test_eggs():
LOGGER.info('eggs info')
LOGGER.warning('eggs warning')
LOGGER.error('eggs error')
LOGGER.critical('eggs critical')
assert True
As you can see, no extra configuration needed; pytest will setup the logger automatically, based on options specified in pytest.ini or passed from command line.
Live logging to terminal, INFO level, fancy output
Configuration in pytest.ini:
[pytest] log_cli = 1 log_cli_level = INFO log_cli_format = %(asctime)s [%(levelname)8s] %(message)s (%(filename)s:%(lineno)s) log_cli_date_format=%Y-%m-%d %H:%M:%S
Running the test:
$ pytest test_spam.py =============================== test session starts ================================ platform darwin -- Python 3.6.4, pytest-3.7.0, py-1.5.3, pluggy-0.7.1 -- /Users/hoefling/.virtualenvs/stackoverflow/bin/python3.6 cachedir: .pytest_cache rootdir: /Users/hoefling/projects/private/stackoverflow/so-4673373, inifile: pytest.ini collected 1 item test_spam.py::test_eggs ---------------------------------- live log call ----------------------------------- 2018-08-01 14:33:20 [ INFO] eggs info (test_spam.py:7) 2018-08-01 14:33:20 [ WARNING] eggs warning (test_spam.py:8) 2018-08-01 14:33:20 [ ERROR] eggs error (test_spam.py:9) 2018-08-01 14:33:20 [CRITICAL] eggs critical (test_spam.py:10) PASSED [100%] ============================= 1 passed in 0.01 seconds =============================
Live logging to terminal and file, only message & CRITICAL level in terminal, fancy output in pytest.log file
Configuration in pytest.ini:
[pytest] log_cli = 1 log_cli_level = CRITICAL log_cli_format = %(message)s log_file = pytest.log log_file_level = DEBUG log_file_format = %(asctime)s [%(levelname)8s] %(message)s (%(filename)s:%(lineno)s) log_file_date_format=%Y-%m-%d %H:%M:%S
Test run:
$ pytest test_spam.py =============================== test session starts ================================ platform darwin -- Python 3.6.4, pytest-3.7.0, py-1.5.3, pluggy-0.7.1 -- /Users/hoefling/.virtualenvs/stackoverflow/bin/python3.6 cachedir: .pytest_cache rootdir: /Users/hoefling/projects/private/stackoverflow/so-4673373, inifile: pytest.ini collected 1 item test_spam.py::test_eggs ---------------------------------- live log call ----------------------------------- eggs critical PASSED [100%] ============================= 1 passed in 0.01 seconds ============================= $ cat pytest.log 2018-08-01 14:38:09 [ INFO] eggs info (test_spam.py:7) 2018-08-01 14:38:09 [ WARNING] eggs warning (test_spam.py:8) 2018-08-01 14:38:09 [ ERROR] eggs error (test_spam.py:9) 2018-08-01 14:38:09 [CRITICAL] eggs critical (test_spam.py:10)
1 Although you can configure pytest in setup.cfg under the [tool:pytest] section, don’t be tempted to do that when you want to provide custom live logging format. Other tools reading setup.cfg might treat stuff like %(message)s as string interpolation and fail. Use pytest.ini to avoid errors.
