161 lines
5.7 KiB
Python
161 lines
5.7 KiB
Python
import asyncio
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import inspect
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from .case import TestCase
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class IsolatedAsyncioTestCase(TestCase):
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# Names intentionally have a long prefix
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# to reduce a chance of clashing with user-defined attributes
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# from inherited test case
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#
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# The class doesn't call loop.run_until_complete(self.setUp()) and family
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# but uses a different approach:
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# 1. create a long-running task that reads self.setUp()
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# awaitable from queue along with a future
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# 2. await the awaitable object passing in and set the result
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# into the future object
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# 3. Outer code puts the awaitable and the future object into a queue
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# with waiting for the future
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# The trick is necessary because every run_until_complete() call
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# creates a new task with embedded ContextVar context.
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# To share contextvars between setUp(), test and tearDown() we need to execute
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# them inside the same task.
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# Note: the test case modifies event loop policy if the policy was not instantiated
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# yet.
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# asyncio.get_event_loop_policy() creates a default policy on demand but never
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# returns None
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# I believe this is not an issue in user level tests but python itself for testing
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# should reset a policy in every test module
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# by calling asyncio.set_event_loop_policy(None) in tearDownModule()
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def __init__(self, methodName='runTest'):
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super().__init__(methodName)
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self._asyncioTestLoop = None
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self._asyncioCallsQueue = None
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async def asyncSetUp(self):
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pass
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async def asyncTearDown(self):
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pass
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def addAsyncCleanup(self, func, /, *args, **kwargs):
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# A trivial trampoline to addCleanup()
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# the function exists because it has a different semantics
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# and signature:
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# addCleanup() accepts regular functions
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# but addAsyncCleanup() accepts coroutines
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#
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# We intentionally don't add inspect.iscoroutinefunction() check
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# for func argument because there is no way
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# to check for async function reliably:
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# 1. It can be "async def func()" iself
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# 2. Class can implement "async def __call__()" method
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# 3. Regular "def func()" that returns awaitable object
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self.addCleanup(*(func, *args), **kwargs)
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def _callSetUp(self):
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self.setUp()
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self._callAsync(self.asyncSetUp)
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def _callTestMethod(self, method):
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self._callMaybeAsync(method)
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def _callTearDown(self):
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self._callAsync(self.asyncTearDown)
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self.tearDown()
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def _callCleanup(self, function, *args, **kwargs):
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self._callMaybeAsync(function, *args, **kwargs)
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def _callAsync(self, func, /, *args, **kwargs):
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assert self._asyncioTestLoop is not None
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ret = func(*args, **kwargs)
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assert inspect.isawaitable(ret)
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fut = self._asyncioTestLoop.create_future()
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self._asyncioCallsQueue.put_nowait((fut, ret))
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return self._asyncioTestLoop.run_until_complete(fut)
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def _callMaybeAsync(self, func, /, *args, **kwargs):
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assert self._asyncioTestLoop is not None
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ret = func(*args, **kwargs)
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if inspect.isawaitable(ret):
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fut = self._asyncioTestLoop.create_future()
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self._asyncioCallsQueue.put_nowait((fut, ret))
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return self._asyncioTestLoop.run_until_complete(fut)
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else:
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return ret
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async def _asyncioLoopRunner(self, fut):
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self._asyncioCallsQueue = queue = asyncio.Queue()
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fut.set_result(None)
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while True:
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query = await queue.get()
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queue.task_done()
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if query is None:
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return
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fut, awaitable = query
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try:
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ret = await awaitable
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if not fut.cancelled():
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fut.set_result(ret)
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except (SystemExit, KeyboardInterrupt):
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raise
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except (BaseException, asyncio.CancelledError) as ex:
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if not fut.cancelled():
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fut.set_exception(ex)
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def _setupAsyncioLoop(self):
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assert self._asyncioTestLoop is None
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loop = asyncio.new_event_loop()
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asyncio.set_event_loop(loop)
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loop.set_debug(True)
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self._asyncioTestLoop = loop
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fut = loop.create_future()
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self._asyncioCallsTask = loop.create_task(self._asyncioLoopRunner(fut))
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loop.run_until_complete(fut)
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def _tearDownAsyncioLoop(self):
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assert self._asyncioTestLoop is not None
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loop = self._asyncioTestLoop
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self._asyncioTestLoop = None
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self._asyncioCallsQueue.put_nowait(None)
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loop.run_until_complete(self._asyncioCallsQueue.join())
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try:
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# cancel all tasks
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to_cancel = asyncio.all_tasks(loop)
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if not to_cancel:
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return
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for task in to_cancel:
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task.cancel()
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loop.run_until_complete(
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asyncio.gather(*to_cancel, loop=loop, return_exceptions=True))
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for task in to_cancel:
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if task.cancelled():
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continue
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if task.exception() is not None:
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loop.call_exception_handler({
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'message': 'unhandled exception during test shutdown',
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'exception': task.exception(),
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'task': task,
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})
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# shutdown asyncgens
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loop.run_until_complete(loop.shutdown_asyncgens())
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finally:
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asyncio.set_event_loop(None)
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loop.close()
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def run(self, result=None):
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self._setupAsyncioLoop()
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try:
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return super().run(result)
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finally:
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self._tearDownAsyncioLoop()
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