test: address Copilot review feedback on test hygiene

- test_migration_processor_extras.py: replace MagicMock() + `del obj.dict`

  with a small dummy class exposing only `model_dump` so the v2 branch is

  exercised without depending on Mock's deletion semantics.

- test_sk_logic_base.py: capture the original `libs.base.SKBase.SKBaseModel`

  before patching with our extra-allow stub and restore it in

  `teardown_module` so the patch no longer leaks across test modules.

Both fixes are confined to test files. Coverage remains above the 82% gate

(backend 93.28%, processor 87.44%).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Shreyas-Microsoft

src/backend-api/src/tests/base/test_sk_logic_base.py

@@ -33,11 +33,33 @@ class _SKBaseModelStub(BaseModel):
     }
 
 
+# Save whatever was on ``SKBase.SKBaseModel`` before this module ran so we can
+# restore it in ``teardown_module`` and avoid leaking our extra-allow stub
+# into subsequent test modules. A sentinel distinguishes "attribute was
+# missing" from "attribute was None".
+_MISSING = object()
+_ORIGINAL_SKBASEMODEL = getattr(_skbase_mod, "SKBaseModel", _MISSING)
+
 # Always force-set our stub so it overrides whatever a previously-loaded
 # test module installed (e.g. test_kernel_agent.py uses a stricter stub
 # without ``extra="allow"`` which prevents SKLogicBase from being constructed).
 _skbase_mod.SKBaseModel = _SKBaseModelStub  # type: ignore[attr-defined]
 
+
+def teardown_module(module):  # noqa: D401 - pytest hook
+    """Restore the original ``SKBaseModel`` attribute on ``libs.base.SKBase``.
+
+    This keeps test ordering deterministic: any test module that imports
+    ``SKBaseModel`` after us sees the original value (or absence) rather than
+    our extra-allow stub. The SUT (``libs.base.SKLogicBase``) is unaffected
+    because it captured the stub at its own import time.
+    """
+    if _ORIGINAL_SKBASEMODEL is _MISSING:
+        if hasattr(_skbase_mod, "SKBaseModel"):
+            delattr(_skbase_mod, "SKBaseModel")
+    else:
+        _skbase_mod.SKBaseModel = _ORIGINAL_SKBASEMODEL  # type: ignore[attr-defined]
+
 # Ensure libs.base.kernel_agent has been imported (creates real
 # semantic_kernel_agent symbol used by the stub below).
 import libs.base.kernel_agent as _kernel_agent_mod  # noqa: E402

src/processor/src/tests/unit/steps/test_migration_processor_extras.py

@@ -39,10 +39,11 @@ def test_details_to_dict_with_dict(self):
         assert WorkflowExecutorFailedException._details_to_dict(d) == d
 
     def test_details_to_dict_with_pydantic_v2_object(self):
-        obj = MagicMock()
-        obj.model_dump = MagicMock(return_value={"executor_id": "v2"})
-        del obj.dict  # ensure we don't fall through to vars()
-        result = WorkflowExecutorFailedException._details_to_dict(obj)
+        class V2Like:
+            def model_dump(self):
+                return {"executor_id": "v2"}
+
+        result = WorkflowExecutorFailedException._details_to_dict(V2Like())
         assert result == {"executor_id": "v2"}
 
     def test_details_to_dict_with_pydantic_v1_object(self):