E9-E12 exercise the launcher's Linux code paths without spawning a
real Firefox binary or Xvfb. They monkeypatch ``sys.platform`` and
stub ``make_virtual_display`` / ``_binary_on_path`` so the tests run
on any host:
- E9 ``_build_prefs(headless=True)`` on Linux passes
``virtual_display=False`` to the translator, so the Win32-only
``security.sandbox.gpu.level`` workaround never leaks into Linux
prefs (Xvfb handles window hiding instead).
- E10 ``_resolve_headless`` on Linux + headless=True invokes the
dispatcher and stores the returned object on ``self._virtual_display``.
- E11 ``_teardown`` stops the Linux virtual display, clears the
reference, and is idempotent on a second call.
- E12 With Xvfb missing from PATH, ``_resolve_headless`` raises a
clear ``RuntimeError`` mentioning ``Xvfb`` instead of a cryptic
FileNotFoundError.
Suite on Linux/WSL: 286 passed, 5 skipped (4 binary-gated E2E
lifecycle tests + 1 Win32 ctypes test). Binary-gated E1/E2/E5/E8
remain ready to run on Linux once the patched Firefox tar.gz is
fetched locally.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
chrissbaumann
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