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File Content: `async_case.py`

import asyncio
import inspect

from .case import TestCase



class IsolatedAsyncioTestCase(TestCase):
    # Names intentionally have a long prefix
    # to reduce a chance of clashing with user-defined attributes
    # from inherited test case
    #
    # The class doesn't call loop.run_until_complete(self.setUp()) and family
    # but uses a different approach:
    # 1. create a long-running task that reads self.setUp()
    #    awaitable from queue along with a future
    # 2. await the awaitable object passing in and set the result
    #    into the future object
    # 3. Outer code puts the awaitable and the future object into a queue
    #    with waiting for the future
    # The trick is necessary because every run_until_complete() call
    # creates a new task with embedded ContextVar context.
    # To share contextvars between setUp(), test and tearDown() we need to execute
    # them inside the same task.

    # Note: the test case modifies event loop policy if the policy was not instantiated
    # yet.
    # asyncio.get_event_loop_policy() creates a default policy on demand but never
    # returns None
    # I believe this is not an issue in user level tests but python itself for testing
    # should reset a policy in every test module
    # by calling asyncio.set_event_loop_policy(None) in tearDownModule()

    def __init__(self, methodName='runTest'):
        super().__init__(methodName)
        self._asyncioTestLoop = None
        self._asyncioCallsQueue = None

    async def asyncSetUp(self):
        pass

    async def asyncTearDown(self):
        pass

    def addAsyncCleanup(self, func, /, *args, **kwargs):
        # A trivial trampoline to addCleanup()
        # the function exists because it has a different semantics
        # and signature:
        # addCleanup() accepts regular functions
        # but addAsyncCleanup() accepts coroutines
        #
        # We intentionally don't add inspect.iscoroutinefunction() check
        # for func argument because there is no way
        # to check for async function reliably:
        # 1. It can be "async def func()" iself
        # 2. Class can implement "async def __call__()" method
        # 3. Regular "def func()" that returns awaitable object
        self.addCleanup(*(func, *args), **kwargs)

    def _callSetUp(self):
        self.setUp()
        self._callAsync(self.asyncSetUp)

    def _callTestMethod(self, method):
        self._callMaybeAsync(method)

    def _callTearDown(self):
        self._callAsync(self.asyncTearDown)
        self.tearDown()

    def _callCleanup(self, function, *args, **kwargs):
        self._callMaybeAsync(function, *args, **kwargs)

    def _callAsync(self, func, /, *args, **kwargs):
        assert self._asyncioTestLoop is not None
        ret = func(*args, **kwargs)
        assert inspect.isawaitable(ret)
        fut = self._asyncioTestLoop.create_future()
        self._asyncioCallsQueue.put_nowait((fut, ret))
        return self._asyncioTestLoop.run_until_complete(fut)

    def _callMaybeAsync(self, func, /, *args, **kwargs):
        assert self._asyncioTestLoop is not None
        ret = func(*args, **kwargs)
        if inspect.isawaitable(ret):
            fut = self._asyncioTestLoop.create_future()
            self._asyncioCallsQueue.put_nowait((fut, ret))
            return self._asyncioTestLoop.run_until_complete(fut)
        else:
            return ret

    async def _asyncioLoopRunner(self, fut):
        self._asyncioCallsQueue = queue = asyncio.Queue()
        fut.set_result(None)
        while True:
            query = await queue.get()
            queue.task_done()
            if query is None:
                return
            fut, awaitable = query
            try:
                ret = await awaitable
                if not fut.cancelled():
                    fut.set_result(ret)
            except (SystemExit, KeyboardInterrupt):
                raise
            except (BaseException, asyncio.CancelledError) as ex:
                if not fut.cancelled():
                    fut.set_exception(ex)

    def _setupAsyncioLoop(self):
        assert self._asyncioTestLoop is None
        loop = asyncio.new_event_loop()
        asyncio.set_event_loop(loop)
        loop.set_debug(True)
        self._asyncioTestLoop = loop
        fut = loop.create_future()
        self._asyncioCallsTask = loop.create_task(self._asyncioLoopRunner(fut))
        loop.run_until_complete(fut)

    def _tearDownAsyncioLoop(self):
        assert self._asyncioTestLoop is not None
        loop = self._asyncioTestLoop
        self._asyncioTestLoop = None
        self._asyncioCallsQueue.put_nowait(None)
        loop.run_until_complete(self._asyncioCallsQueue.join())

        try:
            # cancel all tasks
            to_cancel = asyncio.all_tasks(loop)
            if not to_cancel:
                return

            for task in to_cancel:
                task.cancel()

            loop.run_until_complete(
                asyncio.gather(*to_cancel, loop=loop, return_exceptions=True))

            for task in to_cancel:
                if task.cancelled():
                    continue
                if task.exception() is not None:
                    loop.call_exception_handler({
                        'message': 'unhandled exception during test shutdown',
                        'exception': task.exception(),
                        'task': task,
                    })
            # shutdown asyncgens
            loop.run_until_complete(loop.shutdown_asyncgens())
        finally:
            asyncio.set_event_loop(None)
            loop.close()

    def run(self, result=None):
        self._setupAsyncioLoop()
        try:
            return super().run(result)
        finally:
            self._tearDownAsyncioLoop()
Name	Size	Permission
__pycache__	---	0755
__init__.py	3267 bytes	0644
__main__.py	472 bytes	0644
async_case.py	5810 bytes	0644
case.py	59582 bytes	0644
loader.py	22702 bytes	0644
main.py	11238 bytes	0644
mock.py	98310 bytes	0644
result.py	7442 bytes	0644
runner.py	7767 bytes	0644
signals.py	2403 bytes	0644
suite.py	12815 bytes	0644
util.py	5215 bytes	0644
File Content: async_case.py

File Content: `async_case.py`
