resolve comments

Signed-off-by: Jerry Guo <Jerry.Jinfeng.Guo@alliander.com>

Author: Jerry-Jinfeng-Guo

src/power_grid_model_io/converters/tabular_converter.py

@@ -376,21 +376,19 @@ def _normalize_extra_col_def(self, col_def: Any) -> Any:
 
         # Collect all non-optional_extra column names
         regular_columns = set()
-        normalized_list = []
 
         for item in col_def:
             if isinstance(item, dict) and len(item) == 1 and "optional_extra" in item:
                 # This is an optional_extra section - we'll process it later
-                normalized_list.append(item)
+                pass
             else:
                 # This is a regular column
                 if isinstance(item, str):
                     regular_columns.add(item)
-                normalized_list.append(item)
 
         # Now process optional_extra sections and remove duplicates
         final_list = []
-        for item in normalized_list:
+        for item in col_def:
             if isinstance(item, dict) and len(item) == 1 and "optional_extra" in item:
                 optional_cols = item["optional_extra"]
                 if isinstance(optional_cols, list):

tests/unit/converters/test_tabular_converter.py

@@ -1420,6 +1420,20 @@ def test_optional_extra__mixed_with_required(converter: TabularConverter):
     assert list(result["guid"]) == ["guid1", "guid2"]
 
 
+def test_optional_extra__mixed_with_required_missing_column(converter: TabularConverter):
+    """Test that missing required column raises error even with optional_extra present"""
+    # Arrange
+    data = TabularData(test_table=pd.DataFrame({"id": [1, 2], "name": ["node1", "node2"], "guid": ["guid1", "guid2"]}))
+    # "missing_col" is required but missing
+    col_def = ["name", "missing_col", {"optional_extra": ["guid", "station"]}]
+
+    # Act & Assert
+    with pytest.raises(KeyError, match="missing_col"):
+        converter._parse_col_def(
+            data=data, table="test_table", col_def=col_def, table_mask=None, extra_info=None, allow_missing=False
+        )
+
+
 def test_optional_extra__in_extra_info(converter: TabularConverter):
     """Test that optional_extra works correctly with _handle_extra_info"""
     # Arrange
@@ -1444,6 +1458,23 @@ def test_optional_extra__in_extra_info(converter: TabularConverter):
     assert "station" not in extra_info[200]
 
 
+def test_optional_extra__empty_list_with_extra_info(converter: TabularConverter):
+    """Test that empty optional_extra list results in no updates to extra_info"""
+    # Arrange
+    data = TabularData(test_table=pd.DataFrame({"id": [1, 2], "name": ["node1", "node2"], "guid": ["guid1", "guid2"]}))
+    uuids = np.array([100, 200])
+    extra_info: ExtraInfo = {}
+    col_def: dict[str, list[str]] = {"optional_extra": []}
+
+    # Act
+    converter._handle_extra_info(
+        data=data, table="test_table", col_def=col_def, uuids=uuids, table_mask=None, extra_info=extra_info
+    )
+
+    # Assert
+    assert len(extra_info) == 0
+
+
 def test_optional_extra__all_missing_no_extra_info(converter: TabularConverter):
     """Test that when all optional columns are missing, no extra_info entries are created"""
     # Arrange