I ran this change on anyio==3.0.0 and nothing broke. So it seems like we don't have a test for this (probably the code is covered, but not the logic).

So maybe it's worth adding a quick test before merging this to be sure things work as expected?

def test_accessing_context_from_threaded_sync_endpoint() -> None:

    ctxvar: ContextVar[bytes]  = ContextVar("ctxvar")
    ctxvar.set(b"data")

    def endpoint(request: Request) -> Response:
        return Response(ctxvar.get())
    
    app = Starlette(routes=[Route("/", endpoint)])
    client = TestClient(app)
    
    resp = client.get("/")
    assert resp.content == b"data"

Ooohhh.... nice bit of tidying.
I do like tidying.

I've just noticed that this doesn't work for Python 3.6, so I can expect a pipeline failure on the following commit.

EDIT: To be fair, it didn't work for Python 3.6 before... So not a relevant comment.

Well... That was unexpected...

Maybe import contextvars within the test and otherwise skip the test?

def test_accessing_context_from_threaded_sync_endpoint() -> None:
    try:
        from contextvars import ContextVar
    except ImportError:
        pytest.skip('test requires contextvars package to be available')

    ctxvar: ContextVar[bytes]  = ContextVar("ctxvar")
    ctxvar.set(b"data")

    def endpoint(request: Request) -> Response:
        return Response(ctxvar.get())
    
    app = Starlette(routes=[Route("/", endpoint)])
    client = TestClient(app)
    
    resp = client.get("/")
    assert resp.content == b"data"

Well... That was unexpected...

Maybe because we require the back port on < 3.7? https://github.com/encode/starlette/blob/5a5a5c367f2bac0cb526d417adb59cd2174c3329/setup.py#L43

Well... That was unexpected...

Maybe because we require the back port on < 3.7?

https://github.com/encode/starlette/blob/5a5a5c367f2bac0cb526d417adb59cd2174c3329/setup.py#L43

That's for contextlib, not for contextvars 🤔

AnyIO installs https://pypi.org/project/contextvars/ for Python 3.6 :P

That's for contextlib, not for contextvars 🤔

🤦 my bad

AnyIO installs https://pypi.org/project/contextvars/ for Python 3.6 :P

So I guess we're good then? The test demonstrates that things work, and we know why they work, so I don't see any issue right?

Yep.

The only "issue" is restricting anyio's possible versions. It's also important to say that anyio is working on the 4.0 release.

Besides that, everything is cool.

Since the range of anyio will be >=3.4.0,<5.0, we can merge this 👍

Awesome, thank you @Kludex !