Python 3.7.0 test failures

[bowlofeggs]

Greetings!

I've been working on getting python-backoff to work in Fedora's Rawhide release, which recently upgraded to the recently released Python 3.7. There are three test failures there:

_________________________________________ test_on_exception_coro_cancelling __________________________________________
                                                      
event_loop = <_UnixSelectorEventLoop running=False closed=False debug=False>                                          
                                     
    @pytest.mark.asyncio                                                                                                                                                                                                                     
    def test_on_exception_coro_cancelling(event_loop):      
        sleep_started_event = asyncio.Event()
    
        @backoff.on_predicate(backoff.expo)
        @asyncio.coroutine                               
        def coro():
            sleep_started_event.set()
                
            try:
                yield from asyncio.sleep(10)                                    
            except asyncio.CancelledError:
                return True
    
            return False
    
        task = event_loop.create_task(coro())
    
>       yield from sleep_started_event.wait()
E       TypeError: cannot 'yield from' a coroutine object in a non-coroutine generator

tests/python34/test_backoff_async.py:568: TypeError
_______________________________________ test_on_exception_on_regular_function ________________________________________

    @pytest.mark.asyncio
    def test_on_exception_on_regular_function():
        # Force this function to be a running coroutine.
>       yield from asyncio.sleep(0)
E       TypeError: cannot 'yield from' a coroutine object in a non-coroutine generator

tests/python34/test_backoff_async.py:578: TypeError
_______________________________________ test_on_predicate_on_regular_function ________________________________________

    @pytest.mark.asyncio
    def test_on_predicate_on_regular_function():
        # Force this function to be a running coroutine.
>       yield from asyncio.sleep(0)
E       TypeError: cannot 'yield from' a coroutine object in a non-coroutine generator

tests/python34/test_backoff_async.py:590: TypeError

[bowlofeggs]

This sounds possibly related, though the comments mention that the "yield from" syntax should still work:

https://bugs.python.org/issue32193

[hroncok]

You need #55 or hroncok@274e47d

[bowlofeggs]

Oh thanks @hroncok! Maybe you could make your commit message reference this issue.

[hroncok]

hroncok@5db3029

[bowlofeggs]

I can confirm that #55 solves my build issue.

@hroncok I see that you made a similar but smaller patch - do you recommend I use that in Fedora instead?

[hroncok]

Well #55 solves more problems, maybe use that one instead.

[bowlofeggs]

@hroncok Cool, I will import it into Fedora for now and wait to see what @litl goes with for the long term. Thanks for pointing me in the right direction!

[bgreen-litl]

I'm not sure the right way to handle this yet and It's going to take some time for me to get my head around it. I definitely want to get backoff and tests running cleanly on 3.7 though. Unfortunately I'm not going to have time to dig into this for a couple weeks. In the short term, for you guys, dropping 3.4 support seems reasonable to me.

[bowlofeggs]

Yeah I'm happy to use that cited patch for now in Fedora Rawhide until there's an official merged commit that works with Python 3.7.

[bgreen-litl]

Here is a PR which explicitly supports python 3.7 and drops async support in python 3.4 in the process. #59

[bgreen-litl]

#59 is now merged. I'm planning to release this as part of backoff 2.0 and python 3.7 will work out of the box there.

[bgreen-litl]

@bowlofeggs I ended up releasing this as backoff 1.7.0 - should work out of the box for python 3.7 now

[bowlofeggs]

Thanks!