fix syntax

tests/test_yandex_ai.py

@@ -38,6 +38,15 @@ class FakeChatCompletions:
         return self.completion
 
 
+class FakeHTTPError(RuntimeError):
+    def __init__(self) -> None:
+        super().__init__("forbidden")
+        self.response = SimpleNamespace(
+            status_code=403,
+            text='{"error":{"message":"folder mismatch"}}',
+        )
+
+
 class YandexAIClientTests(unittest.IsolatedAsyncioTestCase):
     def test_multiple_system_messages_are_merged_at_the_beginning(self) -> None:
         self.assertEqual(
@@ -62,11 +71,7 @@ class YandexAIClientTests(unittest.IsolatedAsyncioTestCase):
         )
 
     def test_http_error_includes_safe_response_body(self) -> None:
-        error = RuntimeError("forbidden")
-        error.response = SimpleNamespace(
-            status_code=403,
-            text='{"error":{"message":"folder mismatch"}}',
-        )
+        error = FakeHTTPError()
 
         self.assertEqual(
             describe_yandex_error(error),