It is inconvenient to test code using `async def` using Tahoe's unittest-based testing tools

[exarkun]

There are four base classes for test cases in allmydata.test.common - SyncTestCase, AsyncTestCase, AsyncBrokenTestCase, and TrialTestCase.

None of these allow definition of a test using async def with the behavior you would expect (behavior analogous to what you get from AsyncTestCase and a test method returning a Deferred).

As async def becomes the more popular way to define asynchronous functions and pervasive direct use of Deferred becomes less popular, it would probably be nice if it were at least as convenient to test with async def as it is with Deferred-returning functions.

[itamarst]

There's a decorator that enables one solution to this in test_storage_https.py, async_to_defered (once ​https://github.com/tahoe-lafs/tahoe-lafs/pull/1189 is merged).

[exarkun]

It turns out the change in Twisted 22.8 to make maybeDeferred support coroutines makes both trial and testtools work with async def test methods.