from fastapi import APIRouter, FastAPI, Request from fastapi.responses import JSONResponse from fastapi.testclient import TestClient app = FastAPI() router = APIRouter() @router.route("/items/") def read_items(request: Request): return JSONResponse({"hello": "world"}) app.include_router(router) client = TestClient(app) def test_sub_router(): response = client.get("/items/") assert response.status_code == 200, response.text assert response.json() == {"hello": "world"}