packages/flutter/test/material/flexible_space_bar_collapse_mode_test.dart

// 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/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter_test/flutter_test.dart';

final Key blockKey = UniqueKey();
const double expandedAppbarHeight = 250.0;
final Key appbarContainerKey = UniqueKey();

void main() {
  testWidgets('FlexibleSpaceBar collapse mode none', (WidgetTester tester) async {
    await tester.pumpWidget(
      MaterialApp(
        theme: ThemeData(platform: debugDefaultTargetPlatformOverride),
        home: Scaffold(
          body: CustomScrollView(
            key: blockKey,
            slivers: <Widget>[
              SliverAppBar(
                expandedHeight: expandedAppbarHeight,
                pinned: true,
                flexibleSpace: FlexibleSpaceBar(
                  background: Container(
                    key: appbarContainerKey,
                  ),
                  collapseMode: CollapseMode.none,
                ),
              ),
              SliverToBoxAdapter(
                child: Container(
                  height: 10000.0,
                ),
              ),
            ],
          ),
        ),
      ),
    );

    final Finder appbarContainer = find.byKey(appbarContainerKey);
    final Offset topBeforeScroll = tester.getTopLeft(appbarContainer);
    await slowDrag(tester, blockKey, const Offset(0.0, -100.0));
    final Offset topAfterScroll = tester.getTopLeft(appbarContainer);

    expect(topBeforeScroll.dy, equals(0.0));
    expect(topAfterScroll.dy, equals(0.0));
  }, variant: TargetPlatformVariant(TargetPlatform.values.where((TargetPlatform value) => value != TargetPlatform.fuchsia).toSet()));

  testWidgets('FlexibleSpaceBar collapse mode pin', (WidgetTester tester) async {
    await tester.pumpWidget(
      MaterialApp(
        theme: ThemeData(platform: debugDefaultTargetPlatformOverride),
        home: Scaffold(
          body: CustomScrollView(
            key: blockKey,
            slivers: <Widget>[
              SliverAppBar(
                expandedHeight: expandedAppbarHeight,
                pinned: true,
                flexibleSpace: FlexibleSpaceBar(
                  background: Container(
                    key: appbarContainerKey,
                  ),
                  collapseMode: CollapseMode.pin,
                ),
              ),
              SliverToBoxAdapter(
                child: Container(
                  height: 10000.0,
                ),
              ),
            ],
          ),
        ),
      ),
    );

    final Finder appbarContainer = find.byKey(appbarContainerKey);
    final Offset topBeforeScroll = tester.getTopLeft(appbarContainer);
    await slowDrag(tester, blockKey, const Offset(0.0, -100.0));
    final Offset topAfterScroll = tester.getTopLeft(appbarContainer);

    expect(topBeforeScroll.dy, equals(0.0));
    expect(topAfterScroll.dy, equals(-100.0));
  }, variant: TargetPlatformVariant(TargetPlatform.values.where((TargetPlatform value) => value != TargetPlatform.fuchsia).toSet()));

  testWidgets('FlexibleSpaceBar collapse mode parallax', (WidgetTester tester) async {
    await tester.pumpWidget(
      MaterialApp(
        theme: ThemeData(platform: debugDefaultTargetPlatformOverride),
        home: Scaffold(
          body: CustomScrollView(
            key: blockKey,
            slivers: <Widget>[
              SliverAppBar(
                expandedHeight: expandedAppbarHeight,
                pinned: true,
                flexibleSpace: FlexibleSpaceBar(
                  background: Container(
                    key: appbarContainerKey,
                  ),
                ),
              ),
              SliverToBoxAdapter(
                child: Container(
                  height: 10000.0,
                ),
              ),
            ],
          ),
        ),
      ),
    );

    final Finder appbarContainer = find.byKey(appbarContainerKey);
    final Offset topBeforeScroll = tester.getTopLeft(appbarContainer);
    await slowDrag(tester, blockKey, const Offset(0.0, -100.0));
    final Offset topAfterScroll = tester.getTopLeft(appbarContainer);

    expect(topBeforeScroll.dy, equals(0.0));
    expect(topAfterScroll.dy, lessThan(10.0));
    expect(topAfterScroll.dy, greaterThan(-50.0));
  }, variant: TargetPlatformVariant(TargetPlatform.values.where((TargetPlatform value) => value != TargetPlatform.fuchsia).toSet()));
}

Future<void> slowDrag(WidgetTester tester, Key widget, Offset offset) async {
  final Offset target = tester.getCenter(find.byKey(widget));
  final TestGesture gesture = await tester.startGesture(target);
  await gesture.moveBy(offset);
  await tester.pump(const Duration(milliseconds: 10));
  await gesture.up();
}