blob: 7d44430e888b8f7c1230cddb724d5943a19f6e46 [file] [log] [blame]
// 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 'dart:typed_data';
import 'dart:ui' show window;
import 'package:flutter_test/flutter_test.dart';
import 'package:flutter/services.dart';
import 'package:flutter/widgets.dart';
void main() {
test('Instantiating WidgetsFlutterBinding does neither schedule a frame nor register frame callbacks', () async {
// Regression test for
// Preconditions.
expect(WidgetsBinding.instance, isNull);
expect(window.onBeginFrame, isNull);
expect(window.onDrawFrame, isNull);
// Instantiation does nothing with regards to frame scheduling.
final WidgetsFlutterBinding binding = WidgetsFlutterBinding.ensureInitialized() as WidgetsFlutterBinding;
expect(binding.hasScheduledFrame, isFalse);
expect(window.onBeginFrame, isNull);
expect(window.onDrawFrame, isNull);
// Framework starts with detached statue. Sends resumed signal to enable frame.
final ByteData message = const StringCodec().encodeMessage('AppLifecycleState.resumed');
await ServicesBinding.instance.defaultBinaryMessenger.handlePlatformMessage('flutter/lifecycle', message, (_) { });
// A frame can only be scheduled when there is a root widget.
binding.attachRootWidget(const Placeholder());
// Frame callbacks are registered lazily when a frame is scheduled.
expect(window.onBeginFrame, isNotNull);
expect(window.onDrawFrame, isNotNull);