Fixes RUF017

jupyterlab_server/licenses_handler.py

@@ -58,13 +58,13 @@ def federated_extensions(self) -> dict[str, Any]:
 
             assert isinstance(self.parent, LabServerApp)
 
-        labextensions_path: list = sum(
-            [
-                self.parent.labextensions_path,
-                self.parent.extra_labextensions_path,
-            ],
-            [],
-        )
+        per_paths = [
+            self.parent.labextensions_path,
+            self.parent.extra_labextensions_path,
+        ]
+        labextensions_path = [
+            extension for extensions in per_paths for extension in extensions
+        ]
         return get_federated_extensions(labextensions_path)
 
     async def report_async(

tests/test_workspaces_api.py

@@ -121,9 +121,10 @@ async def test_listing_dates(jp_fetch, labserverapp):
     r = await jp_fetch("lab", "api", "workspaces")
     data = json.loads(r.body.decode())
     values = data["workspaces"]["values"]
-    times: list = sum(
-        ([ws["metadata"].get("last_modified"), ws["metadata"].get("created")] for ws in values), []
-    )
+    workspaces = [
+        [ws["metadata"].get("last_modified"), ws["metadata"].get("created")] for ws in values
+    ]
+    times = [time for workspace in workspaces for time in workspace]
     assert None not in times
     [rfc3339_to_timestamp(t) for t in times]