feat: copy assets out of get_assets

Author: jsignell

CHANGELOG.md

@@ -11,6 +11,7 @@
 ### Changed
 
 - Include a copy of the `fields.json` file (for summaries) with each distribution of PySTAC ([#1045](https://github.com/stac-utils/pystac/pull/1045))
+- Make Catalog, Collection `.get_assets()` return a deepcopy ([#1087](https://github.com/stac-utils/pystac/pull/1087))
 - Removed documentation references to `to_dict` methods returning JSON ([#1074](https://github.com/stac-utils/pystac/pull/1074))
 
 ### Deprecated

pystac/collection.py

@@ -725,15 +725,12 @@ def get_assets(
             Dict[str, Asset]: A dictionary of assets that match ``media_type``
             and/or ``role`` if set or else all of this collection's assets.
         """
-        if media_type is None and role is None:
-            return dict(self.assets.items())
-        assets = dict()
-        for key, asset in self.assets.items():
-            if (media_type is None or asset.media_type == media_type) and (
-                role is None or asset.has_role(role)
-            ):
-                assets[key] = asset
-        return assets
+        return {
+            k: deepcopy(v)
+            for k, v in self.assets.items()
+            if (media_type is None or v.media_type == media_type)
+            and (role is None or v.has_role(role))
+        }
 
     def add_asset(self, key: str, asset: Asset) -> None:
         """Adds an Asset to this item.

pystac/item.py

@@ -256,15 +256,12 @@ def get_assets(
             Dict[str, Asset]: A dictionary of assets that match ``media_type``
                 and/or ``role`` if set or else all of this item's assets.
         """
-        if media_type is None and role is None:
-            return dict(self.assets.items())
-        assets = dict()
-        for key, asset in self.assets.items():
-            if (media_type is None or asset.media_type == media_type) and (
-                role is None or asset.has_role(role)
-            ):
-                assets[key] = asset
-        return assets
+        return {
+            k: deepcopy(v)
+            for k, v in self.assets.items()
+            if (media_type is None or v.media_type == media_type)
+            and (role is None or v.has_role(role))
+        }
 
     def add_asset(self, key: str, asset: Asset) -> None:
         """Adds an Asset to this item.

tests/test_collection.py

@@ -246,7 +246,11 @@ def test_get_assets(self) -> None:
         self.assertCountEqual(multi_filter.keys(), ["thumbnail"])
 
         no_filter = collection.get_assets()
+        self.assertIsNot(no_filter, collection.assets)
         self.assertCountEqual(no_filter.keys(), ["thumbnail"])
+        no_filter["thumbnail"].description = "foo"
+        assert collection.assets["thumbnail"].description != "foo"
+
         no_assets = collection.get_assets(media_type=pystac.MediaType.HDF)
         self.assertEqual(no_assets, {})
 

tests/test_item.py

@@ -179,6 +179,8 @@ def test_get_assets(self) -> None:
             media_type=pystac.MediaType.PNG, role="thumbnail"
         )
         self.assertCountEqual(multi_filter.keys(), ["thumbnail"])
+        multi_filter["thumbnail"].description = "foo"
+        assert item.assets["thumbnail"].description != "foo"
 
         no_filter = item.get_assets()
         self.assertCountEqual(no_filter.keys(), ["analytic", "thumbnail"])