Add an extra SELF_CONTAINED catalog test

tests/test_catalog.py

@@ -837,6 +837,27 @@ def check_all_absolute(cat: Catalog) -> None:
                 c2.catalog_type = CatalogType.ABSOLUTE_PUBLISHED
                 check_all_absolute(c2)
 
+    def test_self_contained_catalog_collection_item_links(self) -> None:
+        with tempfile.TemporaryDirectory() as tmp_dir:
+            cat = TestCases.test_case_9()
+            cat.normalize_hrefs(tmp_dir)
+            cat.validate_all()
+            print(f"Saving catalog to: {tmp_dir}")
+            cat.save(catalog_type=CatalogType.SELF_CONTAINED)
+
+            # read the item back, to make experiment clean
+            item = Item.from_file(
+                f"{tmp_dir}/collection-issue-657/item-issue-657/item-issue-657.json"
+            )
+            # ensure that all links in the output json are relative
+            # everything of a nested level > 2 is not relative?
+            for link in item.links:
+                href = link.get_href()
+                self.assertIsNotNone(href)
+                self.assertFalse(is_absolute_href(href))
+            # use time sleep to pause there and inspect catalogs manually
+            # time.sleep(10000)
+
     def test_full_copy_and_normalize_works_with_created_stac(self) -> None:
         cat = TestCases.test_case_3()
         cat_copy = cat.full_copy()

tests/utils/test_cases.py

@@ -242,3 +242,32 @@ def test_case_8() -> Collection:
                 "data-files/catalogs/" "planet-example-v1.0.0-beta.2/collection.json"
             )
         )
+
+    @staticmethod
+    def test_case_9() -> Catalog:
+        """Manually created STAC Catalog, see issue https://github.com/stac-utils/pystac/issues/657"""
+        catalog = pystac.Catalog(
+            id="catalog-issue-657", description="catalog-issue-657"
+        )
+        collection = pystac.Collection(
+            "collection-issue-657",
+            "collection-issue-657",
+            pystac.Extent(
+                spatial=pystac.SpatialExtent([[-180.0, -90.0, 180.0, 90.0]]),
+                temporal=pystac.TemporalExtent([[datetime(2021, 11, 1), None]]),
+            ),
+            license="proprietary",
+        )
+
+        item = pystac.Item(
+            id="item-issue-657",
+            stac_extensions=[],
+            geometry=ARBITRARY_GEOM,
+            bbox=ARBITRARY_BBOX,
+            datetime=datetime(2021, 11, 1),
+            properties={},
+        )
+
+        collection.add_item(item)
+        catalog.add_child(collection)
+        return catalog