[UnitTests] Add a mock to window.localStorage so that filter tests don't fail if using useLanguage

services/frontend/tests/unit/setup.ts

@@ -0,0 +1,6 @@
+import { vi } from 'vitest'
+
+// Some FilterView filter modules pull in useLanguage -> redux/auth -> apiConnection, which
+// reads window.localStorage at module load time. Stub it so those modules can be imported
+// under Vitest's Node test environment.
+vi.stubGlobal('window', { localStorage: { getItem: () => null } })

services/frontend/vitest.config.ts

@@ -11,6 +11,7 @@ export default defineConfig({
   test: {
     reporters: ['tree'],
     exclude: ['./dist', 'node_modules'],
+    setupFiles: ['./tests/unit/setup.ts'],
     pool: 'threads',
     testTimeout: 10_000, // 10s timeout
     sequence: {