Make get_collection raise if collection_id is empty (#809)

Author: jsignell

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+### Changed
+
+- Make `get_collection` raise if `collection_id` is empty ([#809](https://github.com/stac-utils/pystac-client/pull/809))
+
 ## [v0.9.0] - 2025-07-17
 
 ### Added

pystac_client/client.py

@@ -396,6 +396,9 @@ def get_collection(self, collection_id: str) -> Collection | CollectionClient:
         """
         collection: Collection | CollectionClient | None = None
 
+        if not collection_id:
+            raise ValueError("A `collection_id` must be provided.")
+
         if self._supports_collections():
             assert self._stac_io is not None
 

tests/test_client.py

@@ -801,6 +801,15 @@ def test_get_collection_for_static_catalogs_raise_if_not_found() -> None:
             client.get_collection("country-1")
 
 
+def test_get_collection_raises_if_collection_id_is_empty() -> None:
+    client = Client.from_file(str(TEST_DATA / "test-case-1" / "catalog.json"))
+    with pytest.raises(ValueError, match="A `collection_id` must be provided"):
+        client.get_collection("")
+
+    with pytest.raises(ValueError, match="A `collection_id` must be provided"):
+        client.get_collection(None)
+
+
 @pytest.mark.vcr
 def test_query_string_in_collections_url() -> None:
     # https://github.com/stac-utils/pystac-client/issues/745