Tests trying to find unused ports are flakey when automated

• uvloop version: 0.17.0
• Python version: 3.10
• Platform: nix/darwin
• Can you reproduce the bug with PYTHONASYNCIODEBUG in env?: N/A
• Does uvloop behave differently from vanilla asyncio? How?: N/A

The tests using find_free_port (like https://github.com/MagicStack/uvloop/blob/d2deffefa18653636eb03ea77a5dab6e4febf6c6/tests/test_tcp.py#L252) may fail in busy CI environments. For example building for nixpkgs involves running tests every time. It ends up with: (https://hydra.nixos.org/build/197525892/nixlog/1)

=================================== FAILURES ===================================
_______________________ Test_UV_TCP.test_create_server_5 _______________________
Traceback (most recent call last):
  File "/private/tmp/tmp.xkcj6kx4o4/tests/test_tcp.py", line 245, in test_create_server_5
    self.loop.run_until_complete(runner())
  File "uvloop/loop.pyx", line 1517, in uvloop.loop.Loop.run_until_complete
  File "/private/tmp/tmp.xkcj6kx4o4/tests/test_tcp.py", line 238, in runner
    srv = await self.loop.create_server(
  File "uvloop/loop.pyx", line 1790, in create_server
OSError: [Errno 48] error while attempting to bind on address ('::', 50000, 0, 0): address already in use
_______________________ Test_UV_TCP.test_create_server_6 _______________________
Traceback (most recent call last):
  File "/private/tmp/tmp.xkcj6kx4o4/tests/test_tcp.py", line 271, in test_create_server_6
    self.loop.run_until_complete(runner())
  File "uvloop/loop.pyx", line 1517, in uvloop.loop.Loop.run_until_complete
  File "/private/tmp/tmp.xkcj6kx4o4/tests/test_tcp.py", line 255, in runner
    srv1 = await self.loop.create_server(
  File "uvloop/loop.pyx", line 1790, in create_server
OSError: [Errno 48] error while attempting to bind on address ('::', 50000, 0, 0): address already in use
=============================== warnings summary ===============================

Do those tests need to use a common ipv4/6 socket? Could they use only one protocol at a time with port 0 and then get the local port number from the result?

Or maybe build the retry loop around the first socket creation rather than 2 independent steps?

Bắt đầu trong tests/test_tcp.py, đặc biệt là các test sử dụng find_free_port xung quanh test_create_server_5 và test_create_server_6. Tái hiện các lỗi trong môi trường tự động hoặc bận, sau đó đánh giá việc sử dụng cổng 0, một socket IPv4/IPv6 dùng chung hoặc thử lại việc tạo socket đầu tiên. Công việc được hoàn tất khi các test không còn thất bại vì cổng đã chọn đang được sử dụng.