TestWidgetsFlutterBinding should dispose old RestorationManager on reset. (#133999)

Author: polina-c

packages/flutter_test/lib/src/binding.dart

@@ -244,6 +244,7 @@ abstract class TestWidgetsFlutterBinding extends BindingBase
   /// If [registerTestTextInput] returns true when this method is called,
   /// the [testTextInput] is configured to simulate the keyboard.
   void reset() {
+    _restorationManager?.dispose();
     _restorationManager = null;
     resetGestureBinding();
     testTextInput.reset();

packages/flutter_test/test/bindings_reset_test.dart

@@ -0,0 +1,20 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  test('Disposes restoration manager on reset.', () {
+    final AutomatedTestWidgetsFlutterBinding binding = AutomatedTestWidgetsFlutterBinding();
+    int oldCounter = 0;
+    final TestRestorationManager oldRestorationManager = binding.restorationManager;
+    oldRestorationManager.addListener(() => oldCounter++);
+
+    oldRestorationManager.notifyListeners();
+    expect(oldCounter, 1);
+
+    binding.reset();
+    expect(oldRestorationManager.notifyListeners, throwsA((Object e) => e.toString().contains('disposed')));
+  });
+}