From b409e2fe43fd5fdaebb88c0f6bf80627ded57ed4 Mon Sep 17 00:00:00 2001
From: DJ Melisso <melisso@tetsuwan.com>
Date: Sun, 14 Dec 2025 17:10:51 -0800
Subject: [PATCH] use Union rather than | operator

---
 tests/test_additional_responses_no_mutation.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tests/test_additional_responses_no_mutation.py b/tests/test_additional_responses_no_mutation.py
index 173192f6e6..589b893ed6 100644
--- a/tests/test_additional_responses_no_mutation.py
+++ b/tests/test_additional_responses_no_mutation.py
@@ -4,6 +4,7 @@ don't accumulate duplicate $ref entries in anyOf arrays.
 See https://github.com/fastapi/fastapi/pull/14463
 """
 
+from typing import Union
 from fastapi import FastAPI
 from fastapi.testclient import TestClient
 from pydantic import BaseModel
@@ -20,7 +21,7 @@ class ModelB(BaseModel):
 app = FastAPI(
     responses={
         500: {
-            "model": ModelA | ModelB,
+            "model": Union[ModelA, ModelB],
             "content": {"application/json": {"examples": {"Case A": {"value": "a"}}}},
         }
     }