fix: _AllowedSurfaceIDs.__call__ silently returning None on malformed surface info

doc/changelog.d/5049.fixed.md

@@ -0,0 +1 @@
+_AllowedSurfaceIDs.__call__ silently returning None on malformed surface info

src/ansys/fluent/core/field_data_interfaces.py

@@ -568,13 +568,20 @@ def valid_name(self, surface_name: str) -> str:
 
 class _AllowedSurfaceIDs(_AllowedNames):
     def __call__(self, respect_data_valid: bool = True) -> List[int]:
-        try:
-            return [
-                info["surface_id"][0]
-                for _, info in self._field_info._get_surfaces_info().items()
-            ]
-        except (KeyError, IndexError):
-            pass
+        surface_info = self._field_info._get_surfaces_info()
+        surface_ids = []
+        for surface_name, info in surface_info.items():
+            try:
+                surface_ids.append(info["surface_id"][0])
+            except KeyError:
+                raise LookupError(
+                    f"Failed to retrieve valid surface_id key for surface '{surface_name}'."
+                )
+            except IndexError:
+                raise LookupError(
+                    f"Failed to retrieve valid surface_id index for surface '{surface_name}'."
+                )
+        return surface_ids
 
 
 class FieldUnavailable(RuntimeError):

tests/test_field_data.py

@@ -39,7 +39,9 @@
 from ansys.fluent.core.exceptions import DisallowedValuesError
 from ansys.fluent.core.field_data_interfaces import (
     FieldUnavailable,
+    _AllowedSurfaceIDs,
     _Fields,
+    _SurfaceIds,
 )
 from ansys.fluent.core.services.field_data import (
     CellElementType,
@@ -1017,3 +1019,40 @@ def test_field_data_objects_3d_with_location_objects_overall(
     assert path_lines_data["hot-inlet"].scalar_field_name == "velocity-magnitude"
 
     assert list(path_lines_data["cold-inlet"].lines[100]) == [100, 101]
+
+
+def test_allowed_surface_ids_raises_on_missing_surface_id_key() -> None:
+    """_AllowedSurfaceIDs.__call__ should raise LookupError when surface_id key is missing."""
+
+    class _FakeFieldInfo:
+        def _get_surfaces_info(self):
+            return {"bad-surface": {"no_surface_id_key": []}}
+
+    allowed = _AllowedSurfaceIDs(field_info=_FakeFieldInfo())
+    with pytest.raises(LookupError, match="surface_id key"):
+        allowed()
+
+
+def test_allowed_surface_ids_raises_on_empty_surface_id_list() -> None:
+    """_AllowedSurfaceIDs.__call__ should raise LookupError when surface_id list is empty."""
+
+    class _FakeFieldInfo:
+        def _get_surfaces_info(self):
+            return {"bad-surface": {"surface_id": []}}
+
+    allowed = _AllowedSurfaceIDs(field_info=_FakeFieldInfo())
+    with pytest.raises(LookupError, match="surface_id index"):
+        allowed()
+
+
+def test_surface_ids_validate_raises_on_bad_surface_info() -> None:
+    """_SurfaceIds.validate should propagate LookupError when surface info is malformed."""
+
+    class _FakeFieldInfo:
+        def _get_surfaces_info(self):
+            return {"bad-surface": {"surface_id": []}}
+
+    allowed = _AllowedSurfaceIDs(field_info=_FakeFieldInfo())
+    validator = _SurfaceIds(allowed)
+    with pytest.raises(LookupError, match="surface_id index"):
+        validator.validate([1])