fix: persist account language changes

backend/bot/app/web/webapp/account.py

@@ -482,6 +482,7 @@ async def account_avatar_route(request: web.Request) -> web.Response:
 
 async def account_language_route(request: web.Request) -> web.Response:
     user_id = _require_user_id(request)
+    settings: Settings = request.app["settings"]
     payload = await _read_json(request)
     language_payload, validation_error = _validate_model_payload(WebAppLanguagePayload, payload)
     if validation_error:

tests/test_webapp_account_language.py

@@ -0,0 +1,72 @@
+import json
+from types import SimpleNamespace
+from unittest import IsolatedAsyncioTestCase
+from unittest.mock import AsyncMock, Mock, patch
+
+import bot.app.web.subscription_webapp  # noqa: F401
+from bot.app.web.webapp import account as account_module
+
+
+class _JsonRequest(SimpleNamespace):
+    async def json(self):
+        return self.payload
+
+
+class _SessionFactory:
+    def __init__(self, session):
+        self.session = session
+
+    def __call__(self):
+        return self
+
+    async def __aenter__(self):
+        return self.session
+
+    async def __aexit__(self, exc_type, exc, tb):
+        return False
+
+
+class WebAppAccountLanguageTests(IsolatedAsyncioTestCase):
+    async def test_account_language_route_updates_language_and_invalidates_cache(self):
+        settings = SimpleNamespace()
+        session = SimpleNamespace(
+            flush=AsyncMock(),
+            commit=AsyncMock(),
+            rollback=AsyncMock(),
+        )
+        user = SimpleNamespace(user_id=42, language_code="ru", is_banned=False)
+        i18n = SimpleNamespace(
+            locales_data={"ru": {}, "en": {}},
+            reload_overrides_from_file=Mock(),
+        )
+        request = _JsonRequest(
+            app={
+                "settings": settings,
+                "async_session_factory": _SessionFactory(session),
+                "i18n": i18n,
+            },
+            payload={"language": "en"},
+        )
+
+        with (
+            patch.object(account_module, "_require_user_id", return_value=42),
+            patch.object(
+                account_module.user_dal,
+                "get_user_by_id",
+                AsyncMock(return_value=user),
+            ),
+            patch.object(
+                account_module,
+                "_invalidate_webapp_user_caches",
+                AsyncMock(),
+            ) as invalidate_cache,
+        ):
+            response = await account_module.account_language_route(request)
+
+        self.assertEqual(response.status, 200)
+        self.assertEqual(json.loads(response.text), {"ok": True, "language": "en"})
+        self.assertEqual(user.language_code, "en")
+        i18n.reload_overrides_from_file.assert_called_once_with()
+        session.flush.assert_awaited_once()
+        session.commit.assert_awaited_once()
+        invalidate_cache.assert_awaited_once_with(settings, 42)