def get_app_client(separate_input_output_schemas: bool = True) -> TestClient:
    app = FastAPI(separate_input_output_schemas=separate_input_output_schemas)

    @app.post("/items/", responses={402: {"model": Item}})
    def create_item(item: Item) -> Item:
        return item

    @app.post("/items-list/")
    def create_item_list(item: List[Item]):
        return item

    @app.get("/items/")
    def read_items() -> List[Item]:

        class Item(BaseModel):
            name: str
            description: str | None = None

        app = FastAPI()
        router = APIRouter()

        @router.post("/items/")
        def create_item(item: Item):
            return {"message": "Item created"}

        app.include_router(router)
        ```
        """
        return self.api_route(
            path=path,

* 📝 Update example source files for SQL databases with SQLAlchemy. PR [#9508](https://github.com/tiangolo/fastapi/pull/9508) by [@s-mustafa](https://github.com/s-mustafa).
* 📝 Update code examples in docs for body, replace name `create_item` with `update_item` when appropriate. PR [#5913](https://github.com/tiangolo/fastapi/pull/5913) by [@OttoAndrey](https://github.com/OttoAndrey).