Fix failing extension-negotiation expectation in tests.test_websocket_additional_rfc6455

[MichaelDecent]

Summary

tests.test_websocket_additional_rfc6455 has a failing expectation in test_accept_rejects_extension_negotiation.

Reproduction

uv run python -m unittest -v tests.test_websocket_additional_rfc6455

Current result

• Ran: 3 tests
• Failures: 1
• Failing test:
  • test_accept_rejects_extension_negotiation

Failure details

At:

• tests/test_websocket_additional_rfc6455.py:57

Assertion:

with self.assertRaises(RuntimeError):
    ...

Observed:

• No RuntimeError was raised
• failure: AssertionError: RuntimeError not raised

Notes

The other two tests in this module currently pass, so the mismatch appears localized to extension-negotiation rejection behavior/expectation.

Acceptance criteria

• Clarify intended behavior for extension negotiation in this scenario.
• Align implementation or test expectation accordingly.
• uv run python -m unittest -v tests.test_websocket_additional_rfc6455 passes.

[axtant]

I tested this on master branch using Python v3.13 and the test passes successfully:

py -m uv run py -m unittest -v tests.test_websocket_additional_rfc6455

All 3 tests completed with OK. This issue may already been resolved or may have been environment/version specific.