# coding: utf-8
"""
Module ``case``
---------------
Enhance :class:`unittest.TestCase`:
* a new loop is issued and set as the default loop before each test, and
closed and disposed after,
* if the loop uses a selector, it will be wrapped with
:class:`asynctest.TestSelector`,
* a test method in a TestCase identified as a coroutine function or returning
a coroutine will run on the loop,
* :meth:`~TestCase.setUp()` and :meth:`~TestCase.tearDown()` methods can be
coroutine functions,
* cleanup functions registered with :meth:`~TestCase.addCleanup()` can be
coroutine functions,
* a test fails if the loop did not run during the test.
class-level set-up
~~~~~~~~~~~~~~~~~~
Since each test runs in its own loop, it is not possible to run
:meth:`~TestCase.setUpClass()` and :meth:`~TestCase.tearDownClass()` as
coroutines.
If one needs to perform set-up actions at the class level (meaning
once for all tests in the class), it should be done using a loop created for
this sole purpose and that is not shared with the tests. Ideally, the loop
shall be closed in the method which creates it.
If one really needs to share a loop between tests,
:attr:`TestCase.use_default_loop` can be set to ``True`` (as a class
attribute). The test case will use the loop returned by
:meth:`asyncio.get_event_loop()` instead of creating a new loop for each test.
This way, the event loop or event loop policy can be set during class-level
set-up and tear down.
"""
import asyncio
import functools
import types
import unittest.case
import sys
import warnings
from unittest.case import * # NOQA
import asynctest.selector
import asynctest._fail_on
class _Policy(asyncio.AbstractEventLoopPolicy):
def __init__(self, original_policy, loop, forbid_get_event_loop):
self.original_policy = original_policy
self.forbid_get_event_loop = forbid_get_event_loop
self.loop = loop
self.watcher = None
# we override the loop from the original policy because we don't want to
# instantiate a "default loop" that may be never closed (usually, we only
# run the test, so the "original default loop" is not even created by the
# policy).
def get_event_loop(self):
if self.forbid_get_event_loop:
raise AssertionError("TestCase.forbid_get_event_loop is True, "
"asyncio.get_event_loop() must not be called")
elif self.loop:
return self.loop
else:
return self.original_policy.get_event_loop()
def new_event_loop(self):
return self.original_policy.new_event_loop()
def set_event_loop(self, loop):
result = self.original_policy.set_event_loop(loop)
self.loop = loop
return result
def _check_unix(self):
if not hasattr(asyncio, "SafeChildWatcher"):
raise NotImplementedError
def get_child_watcher(self):
self._check_unix()
if self.loop:
if self.watcher is None:
self.watcher = asyncio.SafeChildWatcher()
self.watcher.attach_loop(self.loop)
return self.watcher
else:
return self.original_policy.get_child_watcher()
def set_child_watcher(self, watcher):
self._check_unix()
if self.loop:
result = self.original_policy.set_child_watcher(watcher)
self.watcher = watcher
return result
else:
return self.original_policy.set_child_watcher(watcher)
def reset_watcher(self):
if self.watcher:
self.watcher.close()
# force the original policy to reissue a child watcher next time
# get_child_watcher() is called, which effectively attach the loop
# to the new watcher. That's the best we can do so far
self.original_policy.set_child_watcher(None)
[docs]class TestCase(unittest.case.TestCase):
"""
A test which is a coroutine function or which returns a coroutine will run
on the loop.
Once the test returned, one or more assertions are checked. For instance,
a test fails if the loop didn't run. These checks can be enabled or
disabled using the :func:`~asynctest.fail_on` decorator.
By default, a new loop is created and is set as the default loop before
each test. Test authors can retrieve this loop with
:attr:`~asynctest.TestCase.loop`.
If :attr:`~asynctest.TestCase.use_default_loop` is set to ``True``, the
current default event loop is used instead. In this case, it is up to the
test author to deal with the state of the loop in each test: the loop might
be closed, callbacks and tasks may be scheduled by previous tests. It is
also up to the test author to close the loop and dispose the related
resources.
If :attr:`~asynctest.TestCase.forbid_get_event_loop` is set to ``True``,
a call to :func:`asyncio.get_event_loop()` will raise an
:exc:`AssertionError`. Since Python 3.6, calling
:func:`asyncio.get_event_loop()` from a callback or a coroutine will return
the running loop (instead of raising an exception).
These behaviors should be configured when defining the test case class::
class With_Reusable_Loop_TestCase(asynctest.TestCase):
use_default_loop = True
forbid_get_event_loop = False
def test_something(self):
pass
If :meth:`setUp()` and :meth:`tearDown()` are coroutine functions, they
will run on the loop. Note that :meth:`setUpClass()` and
:meth:`tearDownClass()` can not be coroutines.
.. versionadded:: 0.5
attribute :attr:`~asynctest.TestCase.use_default_loop`.
.. versionadded:: 0.7
attribute :attr:`~asynctest.TestCase.forbid_get_event_loop`.
In any case, the default loop is now reset to its original state
outside a test function.
.. versionadded:: 0.8
``ignore_loop`` has been deprecated in favor of the extensible
:func:`~asynctest.fail_on` decorator.
"""
#: If true, the loop used by the test case is the current default event
#: loop returned by :func:`asyncio.get_event_loop()`. The loop will not be
#: closed and recreated between tests.
use_default_loop = False
#: If true, the value returned by :func:`asyncio.get_event_loop()` will be
#: set to ``None`` during the test. It allows to ensure that tested code
#: use a loop object explicitly passed around.
forbid_get_event_loop = False
#: Event loop created and set as default event loop during the test.
loop = None
def _init_loop(self):
if self.use_default_loop:
self.loop = asyncio.get_event_loop()
loop = None
else:
loop = self.loop = asyncio.new_event_loop()
policy = _Policy(asyncio.get_event_loop_policy(),
loop, self.forbid_get_event_loop)
asyncio.set_event_loop_policy(policy)
self.loop = self._patch_loop(self.loop)
def _unset_loop(self):
policy = asyncio.get_event_loop_policy()
if not self.use_default_loop:
if sys.version_info >= (3, 6):
self.loop.run_until_complete(self.loop.shutdown_asyncgens())
self.loop.close()
policy.reset_watcher()
asyncio.set_event_loop_policy(policy.original_policy)
self.loop = None
def _patch_loop(self, loop):
if hasattr(loop, '_asynctest_ran'):
# The loop is already patched
return loop
loop._asynctest_ran = False
def wraps(method):
@functools.wraps(method)
def wrapper(self, *args, **kwargs):
try:
return method(*args, **kwargs)
finally:
loop._asynctest_ran = True
return types.MethodType(wrapper, loop)
for method in ('run_forever', 'run_until_complete', ):
setattr(loop, method, wraps(getattr(loop, method)))
if isinstance(loop, asyncio.selector_events.BaseSelectorEventLoop):
loop._selector = asynctest.selector.TestSelector(loop._selector)
return loop
def _setUp(self):
self._init_loop()
# initialize post-test checks
test = getattr(self, self._testMethodName)
checker = getattr(test, asynctest._fail_on._FAIL_ON_ATTR, None)
self._checker = checker or asynctest._fail_on._fail_on()
self._checker.before_test(self)
if asyncio.iscoroutinefunction(self.setUp):
self.loop.run_until_complete(self.setUp())
else:
self.setUp()
# don't take into account if the loop ran during setUp
self.loop._asynctest_ran = False
def _tearDown(self):
if asyncio.iscoroutinefunction(self.tearDown):
self.loop.run_until_complete(self.tearDown())
else:
self.tearDown()
# post-test checks
self._checker.check_test(self)
# Override unittest.TestCase methods which call setUp() and tearDown()
def run(self, result=None):
orig_result = result
if result is None:
result = self.defaultTestResult()
startTestRun = getattr(result, 'startTestRun', None)
if startTestRun is not None:
startTestRun()
result.startTest(self)
testMethod = getattr(self, self._testMethodName)
if (getattr(self.__class__, "__unittest_skip__", False) or
getattr(testMethod, "__unittest_skip__", False)):
# If the class or method was skipped.
try:
skip_why = (getattr(self.__class__, '__unittest_skip_why__', '') or
getattr(testMethod, '__unittest_skip_why__', ''))
self._addSkip(result, self, skip_why)
finally:
result.stopTest(self)
return
expecting_failure = getattr(testMethod,
"__unittest_expecting_failure__", False)
outcome = unittest.case._Outcome(result)
try:
self._outcome = outcome
with outcome.testPartExecutor(self):
self._setUp()
if outcome.success:
outcome.expecting_failure = expecting_failure
with outcome.testPartExecutor(self, isTest=True):
self._run_test_method(testMethod)
outcome.expecting_failure = False
with outcome.testPartExecutor(self):
self._tearDown()
self.loop.run_until_complete(self.doCleanups())
self._unset_loop()
for test, reason in outcome.skipped:
self._addSkip(result, test, reason)
self._feedErrorsToResult(result, outcome.errors)
if outcome.success:
if expecting_failure:
if outcome.expectedFailure:
self._addExpectedFailure(result, outcome.expectedFailure)
else:
self._addUnexpectedSuccess(result)
else:
result.addSuccess(self)
return result
finally:
result.stopTest(self)
if orig_result is None:
stopTestRun = getattr(result, 'stopTestRun', None)
if stopTestRun is not None:
stopTestRun()
# explicitly break reference cycles:
# outcome.errors -> frame -> outcome -> outcome.errors
# outcome.expectedFailure -> frame -> outcome -> outcome.expectedFailure
outcome.errors.clear()
outcome.expectedFailure = None
# clear the outcome, no more needed
self._outcome = None
def debug(self):
self._setUp()
try:
self._run_test_method(getattr(self, self._testMethodName))
self._tearDown()
while self._cleanups:
function, args, kwargs = self._cleanups.pop(-1)
if asyncio.iscoroutinefunction(function):
self.loop.run_until_complete(function(*args, **kwargs))
else:
function(*args, **kwargs)
except Exception:
raise
finally:
self._unset_loop()
def _run_test_method(self, method):
# If the method is a coroutine or returns a coroutine, run it on the
# loop
result = method()
if asyncio.iscoroutine(result):
self.loop.run_until_complete(result)
[docs] @asyncio.coroutine
def doCleanups(self):
"""
Execute all cleanup functions. Normally called for you after tearDown.
"""
outcome = self._outcome or unittest.mock._Outcome()
while self._cleanups:
function, args, kwargs = self._cleanups.pop()
with outcome.testPartExecutor(self):
if asyncio.iscoroutinefunction(function):
yield from function(*args, **kwargs)
else:
function(*args, **kwargs)
return outcome.success
[docs] def addCleanup(self, function, *args, **kwargs):
"""
Add a function, with arguments, to be called when the test is
completed. If function is a coroutine function, it will run on the loop
before it's cleaned.
"""
return super().addCleanup(function, *args, **kwargs)
[docs] @asyncio.coroutine
def assertAsyncRaises(self, exception, awaitable):
"""
Test that an exception of type ``exception`` is raised when an
exception is raised when awaiting ``awaitable``, a future or coroutine.
:see: :meth:`unittest.TestCase.assertRaises()`
"""
with self.assertRaises(exception):
return (yield from awaitable)
[docs] @asyncio.coroutine
def assertAsyncRaisesRegex(self, exception, regex, awaitable):
"""
Like :meth:`assertAsyncRaises()` but also tests that ``regex`` matches
on the string representation of the raised exception.
:see: :meth:`unittest.TestCase.assertRaisesRegex()`
"""
with self.assertRaisesRegex(exception, regex):
return (yield from awaitable)
[docs] @asyncio.coroutine
def assertAsyncWarns(self, warning, awaitable):
"""
Test that a warning is triggered when awaiting ``awaitable``, a future
or a coroutine.
:see: :meth:`unittest.TestCase.assertWarns()`
"""
with self.assertWarns(warning):
return (yield from awaitable)
[docs] @asyncio.coroutine
def assertAsyncWarnsRegex(self, warning, regex, awaitable):
"""
Like :meth:`assertAsyncWarns()` but also tests that ``regex`` matches
on the message of the triggered warning.
:see: :meth:`unittest.TestCase.assertWarnsRegex()`
"""
with self.assertWarnsRegex(warning, regex):
return (yield from awaitable)
[docs]class FunctionTestCase(TestCase, unittest.FunctionTestCase):
"""
Enables the same features as :class:`~asynctest.TestCase`, but for
:class:`~asynctest.FunctionTestCase`.
"""
[docs]class ClockedTestCase(TestCase):
"""
Subclass of :class:`~asynctest.TestCase` with a controlled loop clock,
useful for testing timer based behaviour without slowing test run time.
"""
def _init_loop(self):
super()._init_loop()
self.loop.time = functools.wraps(self.loop.time)(lambda: self._time)
self._time = 0
[docs] @asyncio.coroutine
def advance(self, seconds):
"""
Fast forward time by a number of ``seconds``.
Callbacks scheduled to run up to the destination clock time will be
executed on time:
>>> self.loop.call_later(1, print_time)
>>> self.loop.call_later(2, self.loop.call_later, 1, print_time)
>>> await self.advance(3)
1
3
In this example, the third callback is scheduled at ``t = 2`` to be
executed at ``t + 1``. Hence, it will run at ``t = 3``. The callback as
been called on time.
"""
if seconds < 0:
raise ValueError(
'Cannot go back in time ({} seconds)'.format(seconds))
yield from self._drain_loop()
target_time = self._time + seconds
while True:
next_time = self._next_scheduled()
if next_time is None or next_time > target_time:
break
self._time = next_time
yield from self._drain_loop()
self._time = target_time
yield from self._drain_loop()
def _next_scheduled(self):
try:
return self.loop._scheduled[0]._when
except IndexError:
return None
@asyncio.coroutine
def _drain_loop(self):
while True:
next_time = self._next_scheduled()
if not self.loop._ready and (next_time is None or
next_time > self._time):
break
yield from asyncio.sleep(0)
self.loop._TestCase_asynctest_ran = True
[docs]def ignore_loop(func=None):
"""
Ignore the error case where the loop did not run during the test.
"""
warnings.warn("ignore_loop() is deprecated in favor of "
"fail_on(unused_loop=False)", DeprecationWarning)
checker = asynctest._fail_on._fail_on({"unused_loop": False})
return checker if func is None else checker(func)