bpo-39385: Add an assertNoLogs context manager to unittest.TestCase (GH-18067)

Co-authored-by: Rémi Lapeyre <remi.lapeyre@henki.fr>
This commit is contained in:
Kit Choi 2020-07-01 22:08:38 +01:00 committed by GitHub
parent 5d5c84ef78
commit 6b34d7b51e
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
5 changed files with 131 additions and 8 deletions

View File

@ -950,6 +950,9 @@ Test cases
| :meth:`assertLogs(logger, level) | The ``with`` block logs on *logger* | 3.4 |
| <TestCase.assertLogs>` | with minimum *level* | |
+---------------------------------------------------------+--------------------------------------+------------+
| :meth:`assertNoLogs(logger, level) | The ``with`` block does not log on | 3.10 |
| <TestCase.assertNoLogs>` | *logger* with minimum *level* | |
+---------------------------------------------------------+--------------------------------------+------------+
.. method:: assertRaises(exception, callable, *args, **kwds)
assertRaises(exception, *, msg=None)
@ -1121,6 +1124,24 @@ Test cases
.. versionadded:: 3.4
.. method:: assertNoLogs(logger=None, level=None)
A context manager to test that no messages are logged on
the *logger* or one of its children, with at least the given
*level*.
If given, *logger* should be a :class:`logging.Logger` object or a
:class:`str` giving the name of a logger. The default is the root
logger, which will catch all messages.
If given, *level* should be either a numeric logging level or
its string equivalent (for example either ``"ERROR"`` or
:attr:`logging.ERROR`). The default is :attr:`logging.INFO`.
Unlike :meth:`assertLogs`, nothing will be returned by the context
manager.
.. versionadded:: 3.10
There are also other methods used to perform more specific checks, such as:

View File

@ -26,11 +26,11 @@ class _CapturingHandler(logging.Handler):
class _AssertLogsContext(_BaseTestCaseContext):
"""A context manager used to implement TestCase.assertLogs()."""
"""A context manager for assertLogs() and assertNoLogs() """
LOGGING_FORMAT = "%(levelname)s:%(name)s:%(message)s"
def __init__(self, test_case, logger_name, level):
def __init__(self, test_case, logger_name, level, no_logs):
_BaseTestCaseContext.__init__(self, test_case)
self.logger_name = logger_name
if level:
@ -38,6 +38,7 @@ class _AssertLogsContext(_BaseTestCaseContext):
else:
self.level = logging.INFO
self.msg = None
self.no_logs = no_logs
def __enter__(self):
if isinstance(self.logger_name, logging.Logger):
@ -54,16 +55,31 @@ class _AssertLogsContext(_BaseTestCaseContext):
logger.handlers = [handler]
logger.setLevel(self.level)
logger.propagate = False
if self.no_logs:
return
return handler.watcher
def __exit__(self, exc_type, exc_value, tb):
self.logger.handlers = self.old_handlers
self.logger.propagate = self.old_propagate
self.logger.setLevel(self.old_level)
if exc_type is not None:
# let unexpected exceptions pass through
return False
if len(self.watcher.records) == 0:
self._raiseFailure(
"no logs of level {} or higher triggered on {}"
.format(logging.getLevelName(self.level), self.logger.name))
if self.no_logs:
# assertNoLogs
if len(self.watcher.records) > 0:
self._raiseFailure(
"Unexpected logs found: {!r}".format(
self.watcher.output
)
)
else:
# assertLogs
if len(self.watcher.records) == 0:
self._raiseFailure(
"no logs of level {} or higher triggered on {}"
.format(logging.getLevelName(self.level), self.logger.name))

View File

@ -295,7 +295,6 @@ class _AssertWarnsContext(_AssertRaisesBaseContext):
self._raiseFailure("{} not triggered".format(exc_name))
class _OrderedChainMap(collections.ChainMap):
def __iter__(self):
seen = set()
@ -788,7 +787,16 @@ class TestCase(object):
"""
# Lazy import to avoid importing logging if it is not needed.
from ._log import _AssertLogsContext
return _AssertLogsContext(self, logger, level)
return _AssertLogsContext(self, logger, level, no_logs=False)
def assertNoLogs(self, logger=None, level=None):
""" Fail unless no log messages of level *level* or higher are emitted
on *logger_name* or its children.
This method must be used as a context manager.
"""
from ._log import _AssertLogsContext
return _AssertLogsContext(self, logger, level, no_logs=True)
def _getAssertEqualityFunc(self, first, second):
"""Get a detailed comparison function for the types of the two args.

View File

@ -1681,6 +1681,81 @@ test case
with self.assertLogs('foo'):
log_quux.error("1")
def testAssertLogsUnexpectedException(self):
# Check unexpected exception will go through.
with self.assertRaises(ZeroDivisionError):
with self.assertLogs():
raise ZeroDivisionError("Unexpected")
def testAssertNoLogsDefault(self):
with self.assertRaises(self.failureException) as cm:
with self.assertNoLogs():
log_foo.info("1")
log_foobar.debug("2")
self.assertEqual(
str(cm.exception),
"Unexpected logs found: ['INFO:foo:1']",
)
def testAssertNoLogsFailureFoundLogs(self):
with self.assertRaises(self.failureException) as cm:
with self.assertNoLogs():
log_quux.error("1")
log_foo.error("foo")
self.assertEqual(
str(cm.exception),
"Unexpected logs found: ['ERROR:quux:1', 'ERROR:foo:foo']",
)
def testAssertNoLogsPerLogger(self):
with self.assertNoStderr():
with self.assertLogs(log_quux):
with self.assertNoLogs(logger=log_foo):
log_quux.error("1")
def testAssertNoLogsFailurePerLogger(self):
# Failure due to unexpected logs for the given logger or its
# children.
with self.assertRaises(self.failureException) as cm:
with self.assertLogs(log_quux):
with self.assertNoLogs(logger=log_foo):
log_quux.error("1")
log_foobar.info("2")
self.assertEqual(
str(cm.exception),
"Unexpected logs found: ['INFO:foo.bar:2']",
)
def testAssertNoLogsPerLevel(self):
# Check per-level filtering
with self.assertNoStderr():
with self.assertNoLogs(level="ERROR"):
log_foo.info("foo")
log_quux.debug("1")
def testAssertNoLogsFailurePerLevel(self):
# Failure due to unexpected logs at the specified level.
with self.assertRaises(self.failureException) as cm:
with self.assertNoLogs(level="DEBUG"):
log_foo.debug("foo")
log_quux.debug("1")
self.assertEqual(
str(cm.exception),
"Unexpected logs found: ['DEBUG:foo:foo', 'DEBUG:quux:1']",
)
def testAssertNoLogsUnexpectedException(self):
# Check unexpected exception will go through.
with self.assertRaises(ZeroDivisionError):
with self.assertNoLogs():
raise ZeroDivisionError("Unexpected")
def testAssertNoLogsYieldsNone(self):
with self.assertNoLogs() as value:
pass
self.assertIsNone(value)
def testDeprecatedMethodNames(self):
"""
Test that the deprecated methods raise a DeprecationWarning. See #9424.

View File

@ -0,0 +1,3 @@
A new test assertion context-manager, :func:`unittest.assertNoLogs` will
ensure a given block of code emits no log messages using the logging module.
Contributed by Kit Yan Choi.