Add test for migration and checks of multiple extension versions

Author: jpolchlo

pystac/extensions/classification.py

@@ -641,7 +641,7 @@ def bitfields(self, v: Optional[List[Bitfield]]) -> None:
 
 class ClassificationExtensionHooks(ExtensionHooks):
     schema_uri: str = SCHEMA_URI_PATTERN.format(version=DEFAULT_VERSION)
-    prev_extension_ids = {"classification"}
+    prev_extension_ids = set(ClassificationExtension.get_schema_uris()) - set([ClassificationExtension.get_schema_uri()])
     stac_object_types = {pystac.STACObjectType.ITEM}
 
     def migrate(

tests/extensions/test_classification.py

@@ -11,6 +11,9 @@
 from pystac import Collection, Item
 from pystac.extensions.classification import (
     CLASSES_PROP,
+    SCHEMA_URI_PATTERN,
+    DEFAULT_VERSION,
+    SUPPORTED_VERSIONS,
     Bitfield,
     Classification,
     ClassificationExtension,
@@ -293,3 +296,22 @@ def test_item_assets_extension(collection: Collection) -> None:
     ]
     ext = ClassificationExtension.ext(item_asset)
     ext.__repr__()
+
+
+def test_older_extension_version(landsat_item: Item) -> None:
+    OLD_VERSION = list(set(SUPPORTED_VERSIONS) - set([DEFAULT_VERSION]))[0]
+    new = SCHEMA_URI_PATTERN.format(version=DEFAULT_VERSION)
+    old = SCHEMA_URI_PATTERN.format(version=OLD_VERSION)
+
+    stac_extensions = set(landsat_item.stac_extensions)
+    stac_extensions.remove(new)
+    stac_extensions.add(old)
+    item_as_dict = landsat_item.to_dict(include_self_link=False, transform_hrefs=False)
+    item_as_dict["stac_extensions"] = list(stac_extensions)
+    item = Item.from_dict(item_as_dict)
+    assert ClassificationExtension.has_extension(item)
+    assert old in item.stac_extensions
+
+    migrated_item = pystac.Item.from_dict(item_as_dict, migrate=True)
+    assert ClassificationExtension.has_extension(migrated_item)
+    assert new in migrated_item.stac_extensions