Do not wait forever for test server to start or stop

[akx]

Summary

I was wondering why the test suite just hung forever, and finally with pytest tests/ -vvvx --log-cli-level=DEBUG -s I found that:

[Errno 48] error while attempting to bind on address ('127.0.0.1', 8000): [errno 48] address already in use

– yep, I was working on something else on port 8000 – and so, server.running never becomes True, and tests just hang.

This PR:

• Makes sure errors from server.run() (in the secondary thread) are caught and propagated immediately to the controlling loop
• Adds timeouts, so even if something even more unexpected happens, the suite will error out instead of hanging forever.

Port of PR encode/httpx#3775

Checklist

• I understand that this PR may be closed in case there was no previous discussion. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
  • No separate tests for testing the test fixture 😄
• I've updated the documentation accordingly.
  • No user-facing or developer documentation changes needed. (Noting that port 8000 must not be in use is a separate thing to maybe document, I think...)

[codspeed-hq]

Merging this PR will not alter performance

✅ 15 untouched benchmarks
⏩ 7 skipped benchmarks¹

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_{Comparing akx:test-server-fix-hx2 (fac6261) with main (82b9e2d)}

Footnotes

1. 7 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[cubic-dev-ai]

No issues found across 1 file

_{Re-trigger cubic}

[mbeijen]

Thanks, but we already have #994 merged which makes sure the test select an available port instead of the overused port 8000

[akx]

@mbeijen Great! The fix here is still relevant though: don't wait forever if there's an issue, and surface other exceptions :)