python-rx fails to build with Python 3.10.0a3.

=================================== FAILURES ===================================
______________ TestAsyncIOScheduler.test_asyncio_schedule_action _______________

self = <tests.test_scheduler.test_eventloop.test_asyncioscheduler.TestAsyncIOScheduler testMethod=test_asyncio_schedule_action>

    def test_asyncio_schedule_action(self):
        loop = asyncio.get_event_loop()
    
        @asyncio.coroutine
        def go():
            scheduler = AsyncIOScheduler(loop)
            ran = False
    
            def action(scheduler, state):
                nonlocal ran
                ran = True
    
            scheduler.schedule(action)
    
            yield from asyncio.sleep(0.1, loop=loop)
            assert ran is True
    
>       loop.run_until_complete(go())

tests/test_scheduler/test_eventloop/test_asyncioscheduler.py:42: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
/usr/lib64/python3.10/asyncio/base_events.py:641: in run_until_complete
    return future.result()
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

    @asyncio.coroutine
    def go():
        scheduler = AsyncIOScheduler(loop)
        ran = False
    
        def action(scheduler, state):
            nonlocal ran
            ran = True
    
        scheduler.schedule(action)
    
>       yield from asyncio.sleep(0.1, loop=loop)
E       TypeError: sleep() got an unexpected keyword argument 'loop'

tests/test_scheduler/test_eventloop/test_asyncioscheduler.py:39: TypeError
___________ TestAsyncIOScheduler.test_asyncio_schedule_action_cancel ___________

self = <tests.test_scheduler.test_eventloop.test_asyncioscheduler.TestAsyncIOScheduler testMethod=test_asyncio_schedule_action_cancel>

    def test_asyncio_schedule_action_cancel(self):
        loop = asyncio.get_event_loop()
    
        @asyncio.coroutine
        def go():
            ran = False
            scheduler = AsyncIOScheduler(loop)
    
            def action(scheduler, state):
                nonlocal ran
                ran = True
    
            d = scheduler.schedule_relative(0.05, action)
            d.dispose()
    
            yield from asyncio.sleep(0.3, loop=loop)
            assert ran is False
    
>       loop.run_until_complete(go())

tests/test_scheduler/test_eventloop/test_asyncioscheduler.py:84: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
/usr/lib64/python3.10/asyncio/base_events.py:641: in run_until_complete
    return future.result()
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

    @asyncio.coroutine
    def go():
        ran = False
        scheduler = AsyncIOScheduler(loop)
    
        def action(scheduler, state):
            nonlocal ran
            ran = True
    
        d = scheduler.schedule_relative(0.05, action)
        d.dispose()
    
>       yield from asyncio.sleep(0.3, loop=loop)
E       TypeError: sleep() got an unexpected keyword argument 'loop'

tests/test_scheduler/test_eventloop/test_asyncioscheduler.py:81: TypeError
____________ TestAsyncIOScheduler.test_asyncio_schedule_action_due _____________

self = <tests.test_scheduler.test_eventloop.test_asyncioscheduler.TestAsyncIOScheduler testMethod=test_asyncio_schedule_action_due>

    def test_asyncio_schedule_action_due(self):
        loop = asyncio.get_event_loop()
    
        @asyncio.coroutine
        def go():
            scheduler = AsyncIOScheduler(loop)
            starttime = loop.time()
            endtime = None
    
            def action(scheduler, state):
                nonlocal endtime
                endtime = loop.time()
    
            scheduler.schedule_relative(0.2, action)
    
            yield from asyncio.sleep(0.3, loop=loop)
            assert endtime is not None
            diff = endtime - starttime
            assert diff > 0.18
    
>       loop.run_until_complete(go())

tests/test_scheduler/test_eventloop/test_asyncioscheduler.py:64: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
/usr/lib64/python3.10/asyncio/base_events.py:641: in run_until_complete
    return future.result()
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

    @asyncio.coroutine
    def go():
        scheduler = AsyncIOScheduler(loop)
        starttime = loop.time()
        endtime = None
    
        def action(scheduler, state):
            nonlocal endtime
            endtime = loop.time()
    
        scheduler.schedule_relative(0.2, action)
    
>       yield from asyncio.sleep(0.3, loop=loop)
E       TypeError: sleep() got an unexpected keyword argument 'loop'

tests/test_scheduler/test_eventloop/test_asyncioscheduler.py:59: TypeError
____ TestAsyncIOThreadSafeScheduler.test_asyncio_threadsafe_schedule_action ____

self = <tests.test_scheduler.test_eventloop.test_asynciothreadsafescheduler.TestAsyncIOThreadSafeScheduler testMethod=test_asyncio_threadsafe_schedule_action>

    def test_asyncio_threadsafe_schedule_action(self):
        loop = asyncio.get_event_loop()
    
        @asyncio.coroutine
        def go():
            scheduler = AsyncIOThreadSafeScheduler(loop)
            ran = False
    
            def action(scheduler, state):
                nonlocal ran
                ran = True
    
            def schedule():
                scheduler.schedule(action)
    
            threading.Thread(target=schedule).start()
    
            yield from asyncio.sleep(0.1, loop=loop)
            assert ran is True
    
>       loop.run_until_complete(go())

tests/test_scheduler/test_eventloop/test_asynciothreadsafescheduler.py:46: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
/usr/lib64/python3.10/asyncio/base_events.py:641: in run_until_complete
    return future.result()
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

    @asyncio.coroutine
    def go():
        scheduler = AsyncIOThreadSafeScheduler(loop)
        ran = False
    
        def action(scheduler, state):
            nonlocal ran
            ran = True
    
        def schedule():
            scheduler.schedule(action)
    
        threading.Thread(target=schedule).start()
    
>       yield from asyncio.sleep(0.1, loop=loop)
E       TypeError: sleep() got an unexpected keyword argument 'loop'

tests/test_scheduler/test_eventloop/test_asynciothreadsafescheduler.py:43: TypeError
_ TestAsyncIOThreadSafeScheduler.test_asyncio_threadsafe_schedule_action_cancel _

self = <tests.test_scheduler.test_eventloop.test_asynciothreadsafescheduler.TestAsyncIOThreadSafeScheduler testMethod=test_asyncio_threadsafe_schedule_action_cancel>

    def test_asyncio_threadsafe_schedule_action_cancel(self):
        loop = asyncio.get_event_loop()
    
        @asyncio.coroutine
        def go():
            ran = False
            scheduler = AsyncIOThreadSafeScheduler(loop)
    
            def action(scheduler, state):
                nonlocal ran
                ran = True
    
            def schedule():
                d = scheduler.schedule_relative(0.05, action)
                d.dispose()
    
            threading.Thread(target=schedule).start()
    
            yield from asyncio.sleep(0.3, loop=loop)
            assert ran is False
    
>       loop.run_until_complete(go())

tests/test_scheduler/test_eventloop/test_asynciothreadsafescheduler.py:94: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
/usr/lib64/python3.10/asyncio/base_events.py:641: in run_until_complete
    return future.result()
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

    @asyncio.coroutine
    def go():
        ran = False
        scheduler = AsyncIOThreadSafeScheduler(loop)
    
        def action(scheduler, state):
            nonlocal ran
            ran = True
    
        def schedule():
            d = scheduler.schedule_relative(0.05, action)
            d.dispose()
    
        threading.Thread(target=schedule).start()
    
>       yield from asyncio.sleep(0.3, loop=loop)
E       TypeError: sleep() got an unexpected keyword argument 'loop'

tests/test_scheduler/test_eventloop/test_asynciothreadsafescheduler.py:91: TypeError
__ TestAsyncIOThreadSafeScheduler.test_asyncio_threadsafe_schedule_action_due __

self = <tests.test_scheduler.test_eventloop.test_asynciothreadsafescheduler.TestAsyncIOThreadSafeScheduler testMethod=test_asyncio_threadsafe_schedule_action_due>

    def test_asyncio_threadsafe_schedule_action_due(self):
        loop = asyncio.get_event_loop()
    
        @asyncio.coroutine
        def go():
            scheduler = AsyncIOThreadSafeScheduler(loop)
            starttime = loop.time()
            endtime = None
    
            def action(scheduler, state):
                nonlocal endtime
                endtime = loop.time()
    
            def schedule():
                scheduler.schedule_relative(0.2, action)
    
            threading.Thread(target=schedule).start()
    
            yield from asyncio.sleep(0.3, loop=loop)
            assert endtime is not None
            diff = endtime - starttime
            assert diff > 0.18
    
>       loop.run_until_complete(go())

tests/test_scheduler/test_eventloop/test_asynciothreadsafescheduler.py:71: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
/usr/lib64/python3.10/asyncio/base_events.py:641: in run_until_complete
    return future.result()
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

    @asyncio.coroutine
    def go():
        scheduler = AsyncIOThreadSafeScheduler(loop)
        starttime = loop.time()
        endtime = None
    
        def action(scheduler, state):
            nonlocal endtime
            endtime = loop.time()
    
        def schedule():
            scheduler.schedule_relative(0.2, action)
    
        threading.Thread(target=schedule).start()
    
>       yield from asyncio.sleep(0.3, loop=loop)
E       TypeError: sleep() got an unexpected keyword argument 'loop'

tests/test_scheduler/test_eventloop/test_asynciothreadsafescheduler.py:66: TypeError
=============================== warnings summary ===============================
tests/test_observable/test_fromfuture.py::TestFromFuture::test_future_cancel
  /builddir/build/BUILD/RxPY-3.1.1/tests/test_observable/test_fromfuture.py:67: DeprecationWarning: "@coroutine" decorator is deprecated since Python 3.8, use "async def" instead
    def go():

tests/test_observable/test_fromfuture.py::TestFromFuture::test_future_dispose
  /builddir/build/BUILD/RxPY-3.1.1/tests/test_observable/test_fromfuture.py:91: DeprecationWarning: "@coroutine" decorator is deprecated since Python 3.8, use "async def" instead
    def go():

tests/test_observable/test_fromfuture.py::TestFromFuture::test_future_failure
  /builddir/build/BUILD/RxPY-3.1.1/tests/test_observable/test_fromfuture.py:40: DeprecationWarning: "@coroutine" decorator is deprecated since Python 3.8, use "async def" instead
    def go():

tests/test_observable/test_fromfuture.py::TestFromFuture::test_future_success
  /builddir/build/BUILD/RxPY-3.1.1/tests/test_observable/test_fromfuture.py:15: DeprecationWarning: "@coroutine" decorator is deprecated since Python 3.8, use "async def" instead
    def go():

tests/test_observable/test_start.py::TestStart::test_start_async
  /builddir/build/BUILD/RxPY-3.1.1/tests/test_observable/test_start.py:24: DeprecationWarning: "@coroutine" decorator is deprecated since Python 3.8, use "async def" instead
    def go():

tests/test_observable/test_start.py::TestStart::test_start_async_error
  /builddir/build/BUILD/RxPY-3.1.1/tests/test_observable/test_start.py:44: DeprecationWarning: "@coroutine" decorator is deprecated since Python 3.8, use "async def" instead
    def go():

tests/test_scheduler/test_eventloop/test_asyncioscheduler.py::TestAsyncIOScheduler::test_asyncio_schedule_action
  /builddir/build/BUILD/RxPY-3.1.1/tests/test_scheduler/test_eventloop/test_asyncioscheduler.py:29: DeprecationWarning: "@coroutine" decorator is deprecated since Python 3.8, use "async def" instead
    def go():

tests/test_scheduler/test_eventloop/test_asyncioscheduler.py::TestAsyncIOScheduler::test_asyncio_schedule_action_cancel
  /builddir/build/BUILD/RxPY-3.1.1/tests/test_scheduler/test_eventloop/test_asyncioscheduler.py:70: DeprecationWarning: "@coroutine" decorator is deprecated since Python 3.8, use "async def" instead
    def go():

tests/test_scheduler/test_eventloop/test_asyncioscheduler.py::TestAsyncIOScheduler::test_asyncio_schedule_action_due
  /builddir/build/BUILD/RxPY-3.1.1/tests/test_scheduler/test_eventloop/test_asyncioscheduler.py:48: DeprecationWarning: "@coroutine" decorator is deprecated since Python 3.8, use "async def" instead
    def go():

tests/test_scheduler/test_eventloop/test_asynciothreadsafescheduler.py::TestAsyncIOThreadSafeScheduler::test_asyncio_threadsafe_schedule_action
  /builddir/build/BUILD/RxPY-3.1.1/tests/test_scheduler/test_eventloop/test_asynciothreadsafescheduler.py:30: DeprecationWarning: "@coroutine" decorator is deprecated since Python 3.8, use "async def" instead
    def go():

tests/test_scheduler/test_eventloop/test_asynciothreadsafescheduler.py::TestAsyncIOThreadSafeScheduler::test_asyncio_threadsafe_schedule_action_cancel
  /builddir/build/BUILD/RxPY-3.1.1/tests/test_scheduler/test_eventloop/test_asynciothreadsafescheduler.py:77: DeprecationWarning: "@coroutine" decorator is deprecated since Python 3.8, use "async def" instead
    def go():

tests/test_scheduler/test_eventloop/test_asynciothreadsafescheduler.py::TestAsyncIOThreadSafeScheduler::test_asyncio_threadsafe_schedule_action_due
  /builddir/build/BUILD/RxPY-3.1.1/tests/test_scheduler/test_eventloop/test_asynciothreadsafescheduler.py:52: DeprecationWarning: "@coroutine" decorator is deprecated since Python 3.8, use "async def" instead
    def go():

-- Docs: https://docs.pytest.org/en/stable/warnings.html
=========================== short test summary info ============================
FAILED tests/test_scheduler/test_eventloop/test_asyncioscheduler.py::TestAsyncIOScheduler::test_asyncio_schedule_action
FAILED tests/test_scheduler/test_eventloop/test_asyncioscheduler.py::TestAsyncIOScheduler::test_asyncio_schedule_action_cancel
FAILED tests/test_scheduler/test_eventloop/test_asyncioscheduler.py::TestAsyncIOScheduler::test_asyncio_schedule_action_due
FAILED tests/test_scheduler/test_eventloop/test_asynciothreadsafescheduler.py::TestAsyncIOThreadSafeScheduler::test_asyncio_threadsafe_schedule_action
FAILED tests/test_scheduler/test_eventloop/test_asynciothreadsafescheduler.py::TestAsyncIOThreadSafeScheduler::test_asyncio_threadsafe_schedule_action_cancel
FAILED tests/test_scheduler/test_eventloop/test_asynciothreadsafescheduler.py::TestAsyncIOThreadSafeScheduler::test_asyncio_threadsafe_schedule_action_due
=========== 6 failed, 1296 passed, 10 skipped, 12 warnings in 12.36s ===========

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.10/fedora-rawhide-x86_64/01827908-python-rx/

For all our attempts to build python-rx with Python 3.10, see:
https://copr.fedorainfracloud.org/coprs/g/python/python3.10/package/python-rx/

Testing and mass rebuild of packages is happening in copr. You can follow these instructions to test locally in mock if your package builds with Python 3.10:
https://copr.fedorainfracloud.org/coprs/g/python/python3.10/

Let us know here if you have any questions.

Python 3.10 will be included in Fedora 35. To make that update smoother, we're building Fedora packages with early pre-releases of Python 3.10.
A build failure prevents us from testing all dependent packages (transitive [Build]Requires), so if this package is required a lot, it's important for us to get it fixed soon.
We'd appreciate help from the people who know this package best, but if you don't want to work on this now, let us know so we can try to work around it on our side.