test: scroll service test for editor

frontend/app_flowy/packages/appflowy_editor/test/service/scroll_service_test.dart

@@ -0,0 +1,31 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import '../infra/test_editor.dart';
+
+void main() async {
+  setUpAll(() {
+    TestWidgetsFlutterBinding.ensureInitialized();
+  });
+
+  group('Testing Scroll With Gestures', () {
+    testWidgets('Test Gestsure Scroll', (tester) async {
+      final editor = tester.editor;
+      for (var i = 0; i < 100; i++) {
+        editor.insertTextNode('$i');
+      }
+      editor.insertTextNode('mark');
+      for (var i = 100; i < 200; i++) {
+        editor.insertTextNode('$i');
+      }
+      await editor.startTesting();
+
+      final listFinder = find.byType(Scrollable);
+      final itemFinder = find.text('mark', findRichText: true);
+
+      await tester.scrollUntilVisible(itemFinder, 500.0,
+          scrollable: listFinder);
+
+      expect(itemFinder, findsOneWidget);
+    });
+  });
+}