Test: Add coverage for BackgroundTasks collection and pragma for unreachable code

fastapi/routing.py

@@ -412,7 +412,7 @@ def get_request_handler(
                     # solved_result.background_tasks is always BackgroundTasks (from dependencies/utils.py)
                     if isinstance(solved_result.background_tasks, BackgroundTasks):
                         combined_tasks.tasks.extend(solved_result.background_tasks.tasks)
-                    elif isinstance(solved_result.background_tasks, BackgroundTask):
+                    elif isinstance(solved_result.background_tasks, BackgroundTask):  # pragma: no cover
                          # Should not happen for BackgroundTasks dependency but safe to handle
                         combined_tasks.tasks.append(solved_result.background_tasks)
                         

tests/test_issue_11215_coverage.py

@@ -0,0 +1,26 @@
+from fastapi import BackgroundTasks, FastAPI
+from fastapi.testclient import TestClient
+from starlette.background import BackgroundTasks as StarletteBackgroundTasks
+from starlette.responses import Response
+
+app = FastAPI()
+
+@app.get("/")
+def endpoint(tasks: BackgroundTasks):
+    tasks.add_task(lambda: print("Dependency task"))
+    
+    response_tasks = StarletteBackgroundTasks()
+    response_tasks.add_task(lambda: print("Response task"))
+    
+    return Response(
+        content="Custom response",
+        background=response_tasks,
+    )
+
+client = TestClient(app)
+
+def test_issue_11215_response_background_tasks_collection(capsys):
+    client.get("/")
+    captured = capsys.readouterr()
+    assert "Dependency task" in captured.out
+    assert "Response task" in captured.out