diff --git a/tests/test_router_mount.py b/tests/test_router_mount.py
index 0a36544c9f..7fffe75cee 100644
--- a/tests/test_router_mount.py
+++ b/tests/test_router_mount.py
@@ -1,20 +1,23 @@
-from fastapi import FastAPI, APIRouter
-from fastapi.testclient import TestClient
+from fastapi import APIRouter, FastAPI
 
 app = FastAPI()
 api_router = APIRouter(prefix="/api")
 
+
 @api_router.get("/app")
 def read_main():
     return {"message": "Hello World from main app"}
 
+
 subapi = FastAPI()
 
+
 @subapi.get("/sub")
 def read_sub():
     return {"message": "Hello World from sub API"}
 
+
 api_router.mount("/subapi", subapi)  # ← moved up
-app.include_router(api_router)       # ← now after
+app.include_router(api_router)  # ← now after
 
-print("All tests passed.")
\ No newline at end of file
+print("All tests passed.")