Fix catalog shallow copy changing class type (#3950)

* Catalog shallow copy should use specified class type and not cast to DataCatalog

Signed-off-by: Merel Theisen <[email protected]>

RELEASE.md

@@ -4,6 +4,7 @@
 
 ## Bug fixes and other changes
 * Updated error message for invalid catalog entries.
+* Fixed a bug in the `DataCatalog` `shallow_copy()` method to ensure it returns the type of the used catalog and doesn't cast it to `DataCatalog`.
 
 ## Breaking changes to the API
 

kedro/io/data_catalog.py

@@ -761,7 +761,7 @@ def shallow_copy(
             dataset_patterns = self._sort_patterns(unsorted_dataset_patterns)
         else:
             dataset_patterns = self._dataset_patterns
-        return DataCatalog(
+        return self.__class__(
             datasets=self._datasets,
             dataset_patterns=dataset_patterns,
             load_versions=self._load_versions,

tests/io/test_data_catalog.py

@@ -426,11 +426,21 @@ def test_confirm(self, mocker, caplog):
         ],
     )
     def test_bad_confirm(self, data_catalog, dataset_name, error_pattern):
-        """Test confirming a non existent dataset or one that
+        """Test confirming a non-existent dataset or one that
         does not have `confirm` method"""
         with pytest.raises(DatasetError, match=re.escape(error_pattern)):
             data_catalog.confirm(dataset_name)
 
+    def test_shallow_copy_returns_correct_class_type(
+        self,
+    ):
+        class MyDataCatalog(DataCatalog):
+            pass
+
+        data_catalog = MyDataCatalog()
+        copy = data_catalog.shallow_copy()
+        assert isinstance(copy, MyDataCatalog)
+
 
 class TestDataCatalogFromConfig:
     def test_from_sane_config(self, data_catalog_from_config, dummy_dataframe):