fix: add simple test for l10n

frontend/app_flowy/packages/appflowy_editor/test/l10n/l10n_test.dart

@@ -0,0 +1,19 @@
+import 'package:appflowy_editor/appflowy_editor.dart';
+import 'package:flutter_test/flutter_test.dart';
+import '../infra/test_editor.dart';
+
+void main() async {
+  setUpAll(() {
+    TestWidgetsFlutterBinding.ensureInitialized();
+  });
+
+  group('l10n.dart', () {
+    for (final locale
+        in AppFlowyEditorLocalizations.delegate.supportedLocales) {
+      testWidgets('test localization', (tester) async {
+        final editor = tester.editor..insertTextNode('');
+        await editor.startTesting(locale: locale);
+      });
+    }
+  });
+}