fix(tests): isolate session route import stubs

Keeps src.request_models real and restores both sys.modules and parent routes.session_routes package attributes after temporary test stubs. Restores one focused part of the Python CI baseline tracked in #2580.

tests/test_session_ghost_delete.py

@@ -27,17 +27,61 @@ import pytest
 # MagicMock sqlalchemy stub. The real core.database defines declarative classes
 # that blow up under that stub, so temporarily swap in MagicMock module objects
 # (auto-creating attributes satisfy any `from core.database import X`). Crucially
-# we RESTORE sys.modules immediately after import so these stubs never leak into
-# sibling test modules — the imported SM/SR objects keep their captured bindings.
+# we RESTORE both sys.modules AND the parent `routes` package attribute after
+# import, so these stubs never leak into sibling modules — the local SM/SR
+# bindings keep their captured stub modules for this file's own assertions.
 _ABSENT = object()
-_TEMP_STUBS = ("core.database", "core.models", "src.request_models")
+
+
+def _save_module_and_parent_attr(dotted_name):
+    """Capture a module's sys.modules entry *and* its parent-package attribute.
+
+    Importing ``routes.session_routes`` also sets ``session_routes`` on the
+    parent ``routes`` package object, and ``import routes.session_routes as X``
+    resolves ``X`` through that parent attribute — so restoring sys.modules
+    alone leaves the stale stub-bound module reachable. Returns a (module, attr)
+    pair to hand back to _restore_module_and_parent_attr.
+    """
+    saved_module = sys.modules.get(dotted_name, _ABSENT)
+    pkg_name, _, attr = dotted_name.rpartition(".")
+    pkg = sys.modules.get(pkg_name)
+    saved_attr = getattr(pkg, attr, _ABSENT) if pkg is not None else _ABSENT
+    return saved_module, saved_attr
+
+
+def _restore_module_and_parent_attr(dotted_name, saved_module, saved_attr):
+    """Restore (or remove) both the sys.modules entry and the parent attribute.
+
+    Passing _ABSENT for both clears the cache, which is how we drop any stale
+    entry before the stubbed import.
+    """
+    if saved_module is _ABSENT:
+        sys.modules.pop(dotted_name, None)
+    else:
+        sys.modules[dotted_name] = saved_module
+    pkg_name, _, attr = dotted_name.rpartition(".")
+    pkg = sys.modules.get(pkg_name)
+    if pkg is None:
+        return
+    if saved_attr is _ABSENT:
+        if hasattr(pkg, attr):
+            delattr(pkg, attr)
+    else:
+        setattr(pkg, attr, saved_attr)
+
+
+_TEMP_STUBS = ("core.database", "core.models")
 _saved = {name: sys.modules.get(name, _ABSENT) for name in _TEMP_STUBS}
 _saved["core.session_manager"] = sys.modules.get("core.session_manager", _ABSENT)
+_sr_saved = _save_module_and_parent_attr("routes.session_routes")
 try:
     for _name in _TEMP_STUBS:
         sys.modules[_name] = MagicMock(name=_name)
     if isinstance(sys.modules.get("core.session_manager"), MagicMock):
         del sys.modules["core.session_manager"]
+    # Clear the sys.modules entry AND the parent `routes` attribute so the
+    # stubbed import below produces a fresh module with no stale binding behind it.
+    _restore_module_and_parent_attr("routes.session_routes", _ABSENT, _ABSENT)
     SM = importlib.import_module("core.session_manager")
     import routes.session_routes as SR  # noqa: E402
 finally:
@@ -46,6 +90,7 @@ finally:
             sys.modules.pop(_name, None)
         else:
             sys.modules[_name] = _val
+    _restore_module_and_parent_attr("routes.session_routes", *_sr_saved)
 
 from fastapi import HTTPException  # noqa: E402