code: def test_main():
      response = client.get("/app")
      assert response.status_code == 200
      assert response.json() == {
          "message": "Hello World",
          "root_path": "/api/v1",
      }
  
imports: from dirty_equals import IsOneOf
  from fastapi.testclient import TestClient
  from docs_src.behind_a_proxy.tutorial004 import app
label_desc: Use image node_id 1 for calling a global function with example usage: test_main() without return types