pytest Session Configuration — oc_diagnostics
==============================================
Purpose
-------
Provide a single session-scoped pytest fixture that suppresses the one-shot
pre-init ``RuntimeWarning`` for the full pytest test session.
Background
----------
``unified_debug._dbg()`` emits a one-shot ``RuntimeWarning`` the first time it
is called before ``oc_diagnostics.init()`` has been called. This is correct
and useful behaviour in production — but in the test suite, ``init()`` is
intentionally omitted from every test to avoid installing stream interceptors or
writing log files. As a result, the first test that instantiates
``DiagnosticsMiddleware`` (or any other code that calls ``_dbg()`` at class
construction time) triggers the warning as a false positive.
``run_tests.py`` already handles this by setting ``_init_warned = True`` at the
top of ``main()``. This ``conftest.py`` provides the equivalent suppression for
direct pytest invocations (e.g. ``pytest tests/``, ``pytest tests/test_fastapi_middleware.py``).
Effect on ``test_dbg_before_init_warning``
------------------------------------------
That test explicitly exercises the one-shot warning mechanism. It saves
``_init_warned``, resets it to ``False`` in its own setup, and restores it in
``finally``. The session fixture does not interfere because the test owns its
own state transitions.
Contracts
---------
- Must not start servers or modify persistent state.
- Must not suppress legitimate ``RuntimeWarning`` instances from production code.
- ``test_dbg_before_init_warning`` must continue to pass unchanged.
1.15.0