42 lines
1.6 KiB
Dart
42 lines
1.6 KiB
Dart
// Copyright 2014 The Flutter Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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// @dart = 2.8
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import 'dart:typed_data';
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import 'dart:ui' show window;
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import 'package:flutter_test/flutter_test.dart';
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import 'package:flutter/services.dart';
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import 'package:flutter/widgets.dart';
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void main() {
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test('Instantiating WidgetsFlutterBinding does neither schedule a frame nor register frame callbacks', () async {
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// Regression test for https://github.com/flutter/flutter/issues/39494.
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// Preconditions.
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expect(WidgetsBinding.instance, isNull);
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expect(window.onBeginFrame, isNull);
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expect(window.onDrawFrame, isNull);
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// Instantiation does nothing with regards to frame scheduling.
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final WidgetsFlutterBinding binding = WidgetsFlutterBinding.ensureInitialized() as WidgetsFlutterBinding;
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expect(binding.hasScheduledFrame, isFalse);
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expect(window.onBeginFrame, isNull);
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expect(window.onDrawFrame, isNull);
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// Framework starts with detached statue. Sends resumed signal to enable frame.
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final ByteData message = const StringCodec().encodeMessage('AppLifecycleState.resumed');
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await ServicesBinding.instance.defaultBinaryMessenger.handlePlatformMessage('flutter/lifecycle', message, (_) { });
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// A frame can only be scheduled when there is a root widget.
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binding.attachRootWidget(const Placeholder());
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// Frame callbacks are registered lazily when a frame is scheduled.
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binding.scheduleFrame();
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expect(window.onBeginFrame, isNotNull);
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expect(window.onDrawFrame, isNotNull);
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});
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}
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