Fix socket port 0 error

[euri10]

Fixes #974 from possibly a typo introduced in https://github.com/encode/uvicorn/pull/930/files#diff-716652db9a2feab62038753117d5e4fd4294f213f4c7f2edcb47b5788e5209f6L158-R190

I wanted to write a test, natural place seemed to be in

uvicorn/tests/test_main.py

Lines 29 to 43 in 83303ff

	@pytest.mark.asyncio
	@pytest.mark.parametrize(
	"host, url",
	[
	pytest.param(None, "http://127.0.0.1:8000", id="default"),
	pytest.param("localhost", "http://127.0.0.1:8000", id="hostname"),
	pytest.param("::1", "http://[::1]:8000", id="ipv6"),
	],
	)
	async def test_run(host, url):
	config = Config(app=app, host=host, loop="asyncio", limit_max_requests=1)
	async with run_server(config):
	async with httpx.AsyncClient() as client:
	response = await client.get(url)
	assert response.status_code == 204

unfortunately I can see now way of getting the random assigned port (or the server socket for the same purpose) when we pass a port=0 after it has been created.
do you have an idea @florimondmanca ?

[florimondmanca]

👍 OK on the typo.

Not sure about the test, I think there's a way if we access server._server.sockets, but it would need a dedicated test since the run_server() helper is not enough for that.

[selimb]

It’d be possible, although perhaps not the cleanest, to verify the port by checking the logs?

[euri10]

yep probably, but I think the better solution would be to effectively check it from the server object and get it in the run_server we use in the test utils.
if you fancy sending a PR, it's welcomed :)
also I just tested this on linux, so hopefully the fix is valid also on windows