py.test plugin to catch log messages. This is a fork of pytest-capturelog.
As of pytest 3.3, the functionality of this plugin has been merged to the pytest core. See the pytest logging documentation for details.
The pytest-catchlog package may be installed with pip or easy_install:
pip install pytest-catchlog easy_install pytest-catchlog
If the plugin is installed log messages are captured by default and for each failed test will be shown in the same manner as captured stdout and stderr.
Running without options:
py.test
Shows failed tests like so:
----------------------- Captured stdlog call ---------------------- test_reporting.py 26 INFO text going to logger ----------------------- Captured stdout call ---------------------- text going to stdout ----------------------- Captured stderr call ---------------------- text going to stderr ==================== 2 failed in 0.02 seconds =====================
By default each captured log message shows the module, line number, log level and message. Showing the exact module and line number is useful for testing and debugging. If desired the log format and date format can be specified to anything that the logging module supports.
Running pytest specifying formatting options:
py.test --log-format="%(asctime)s %(levelname)s %(message)s" \
--log-date-format="%Y-%m-%d %H:%M:%S"
Shows failed tests like so:
----------------------- Captured stdlog call ---------------------- 2010-04-10 14:48:44 INFO text going to logger ----------------------- Captured stdout call ---------------------- text going to stdout ----------------------- Captured stderr call ---------------------- text going to stderr ==================== 2 failed in 0.02 seconds =====================
These options can also be customized through a configuration file:
[pytest] log_format = %(asctime)s %(levelname)s %(message)s log_date_format = %Y-%m-%d %H:%M:%S
Although the same effect could be achieved through the addopts setting,
using dedicated options should be preferred since the latter doesn't
force other developers to have pytest-catchlog installed (while at
the same time, addopts approach would fail with 'unrecognized arguments'
error). Command line arguments take precedence.
Further it is possible to disable reporting logs on failed tests completely with:
py.test --no-print-logs
Or in you pytest.ini:
[pytest] log_print=False
Shows failed tests in the normal manner as no logs were captured:
----------------------- Captured stdout call ---------------------- text going to stdout ----------------------- Captured stderr call ---------------------- text going to stderr ==================== 2 failed in 0.02 seconds =====================
Inside tests it is possible to change the log level for the captured
log messages. This is supported by the caplog fixture:
def test_foo(caplog):
caplog.set_level(logging.INFO)
pass
By default the level is set on the handler used to catch the log messages, however as a convenience it is also possible to set the log level of any logger:
def test_foo(caplog):
caplog.set_level(logging.CRITICAL, logger='root.baz')
pass
It is also possible to use a context manager to temporarily change the log level:
def test_bar(caplog):
with caplog.at_level(logging.INFO):
pass
Again, by default the level of the handler is affected but the level of any logger can be changed instead with:
def test_bar(caplog):
with caplog.at_level(logging.CRITICAL, logger='root.baz'):
pass
Lastly all the logs sent to the logger during the test run are made available on the fixture in the form of both the LogRecord instances and the final log text. This is useful for when you want to assert on the contents of a message:
def test_baz(caplog):
func_under_test()
for record in caplog.records:
assert record.levelname != 'CRITICAL'
assert 'wally' not in caplog.text
For all the available attributes of the log records see the
logging.LogRecord class.
You can also resort to record_tuples if all you want to do is to ensure,
that certain messages have been logged under a given logger name with a
given severity and message:
def test_foo(caplog):
logging.getLogger().info('boo %s', 'arg')
assert caplog.record_tuples == [
('root', logging.INFO, 'boo arg'),
]
You can call caplog.clear() to reset the captured log records in a test:
def test_something_with_clearing_records(caplog):
some_method_that_creates_log_records()
caplog.clear()
your_test_method()
assert ['Foo'] == [rec.message for rec in caplog.records]
By default, catchlog will output any logging records with a level higher or equal
to WARNING. In order to actually see these logs in the console you have to disable
pytest output capture by passing -s.
You can specify the logging level for which log records with equal or higher level
are printed to the console by passing --log-cli-level. This setting accepts the
logging level names as seen in python's documentation or an integer as the logging
level num.
Additionally, you can also specify --log-cli-format and --log-cli-date-format
which mirror and default to --log-format and --log-date-format if not
provided, but are applied only to the console logging handler.
All of the CLI log options can also be set in the configuration INI file. The option names are:
log_cli_levellog_cli_formatlog_cli_date_format
If you need to record the whole test suite logging calls to a file, you can
pass
--log-file=/path/to/log/file. This log file is opened in write mode which means
that it will be overwritten at each run tests session.
You can also specify the logging level for the log file by passing
--log-file-level. This setting accepts the logging level names as seen in python's
documentation(ie, uppercased level names) or an integer as the logging level num.
Additionally, you can also specify --log-file-format and --log-file-date-format
which are equal to --log-format and --log-date-format but are applied to the
log file logging handler.
All of the log file options can also be set in the configuration INI file. The option names are:
log_filelog_file_levellog_file_formatlog_file_date_format