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// 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';
import 'package:flutter/widgets.dart';
// Assuming that the test container is 800x600. The height of the
// viewport's contents is 650.0, the top and bottom text children
// are 100 pixels high and top/left edge of both widgets are visible.
// The top of the bottom widget is at 550 (the top of the top widget
// is at 0). The top of the bottom widget is 500 when it has been
// scrolled completely into view.
Widget buildFrame(ScrollPhysics physics, { ScrollController scrollController }) {
return SingleChildScrollView(
key: UniqueKey(),
physics: physics,
controller: scrollController,
child: SizedBox(
height: 650.0,
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
textDirection: TextDirection.ltr,
children: <Widget>[
const SizedBox(height: 100.0, child: Text('top', textDirection: TextDirection.ltr)),
Expanded(child: Container()),
const SizedBox(height: 100.0, child: Text('bottom', textDirection: TextDirection.ltr)),
],
),
),
);
}
void main() {
testWidgets('ClampingScrollPhysics', (WidgetTester tester) async {
// Scroll the target text widget by offset and then return its origin
// in global coordinates.
Future<Offset> locationAfterScroll(String target, Offset offset) async {
await tester.dragFrom(tester.getTopLeft(find.text(target)), offset);
await tester.pump();
final RenderBox textBox = tester.renderObject(find.text(target));
final Offset widgetOrigin = textBox.localToGlobal(Offset.zero);
await tester.pump(const Duration(seconds: 1)); // Allow overscroll to settle
return Future<Offset>.value(widgetOrigin);
}
await tester.pumpWidget(buildFrame(const BouncingScrollPhysics()));
Offset origin = await locationAfterScroll('top', const Offset(0.0, 400.0));
expect(origin.dy, greaterThan(0.0));
origin = await locationAfterScroll('bottom', const Offset(0.0, -400.0));
expect(origin.dy, lessThan(500.0));
await tester.pumpWidget(buildFrame(const ClampingScrollPhysics()));
origin = await locationAfterScroll('top', const Offset(0.0, 400.0));
expect(origin.dy, equals(0.0));
origin = await locationAfterScroll('bottom', const Offset(0.0, -400.0));
expect(origin.dy, equals(500.0));
});
testWidgets('ClampingScrollPhysics affects ScrollPosition', (WidgetTester tester) async {
// BouncingScrollPhysics
await tester.pumpWidget(buildFrame(const BouncingScrollPhysics()));
ScrollableState scrollable = tester.state(find.byType(Scrollable));
await tester.dragFrom(tester.getTopLeft(find.text('top')), const Offset(0.0, 400.0));
await tester.pump();
expect(scrollable.position.pixels, lessThan(0.0));
await tester.pump(const Duration(seconds: 1)); // Allow overscroll to settle
await tester.dragFrom(tester.getTopLeft(find.text('bottom')), const Offset(0.0, -400.0));
await tester.pump();
expect(scrollable.position.pixels, greaterThan(0.0));
await tester.pump(const Duration(seconds: 1)); // Allow overscroll to settle
// ClampingScrollPhysics
await tester.pumpWidget(buildFrame(const ClampingScrollPhysics()));
scrollable = scrollable = tester.state(find.byType(Scrollable));
await tester.dragFrom(tester.getTopLeft(find.text('top')), const Offset(0.0, 400.0));
await tester.pump();
expect(scrollable.position.pixels, equals(0.0));
await tester.pump(const Duration(seconds: 1)); // Allow overscroll to settle
await tester.dragFrom(tester.getTopLeft(find.text('bottom')), const Offset(0.0, -400.0));
await tester.pump();
expect(scrollable.position.pixels, equals(50.0));
});
testWidgets('ClampingScrollPhysics handles out of bounds ScrollPosition', (WidgetTester tester) async {
Future<void> testOutOfBounds(ScrollPhysics physics, double initialOffset, double expectedOffset) async {
final ScrollController scrollController = ScrollController(initialScrollOffset: initialOffset);
await tester.pumpWidget(buildFrame(physics, scrollController: scrollController));
final ScrollableState scrollable = tester.state(find.byType(Scrollable));
expect(scrollable.position.pixels, equals(initialOffset));
await tester.pump(const Duration(seconds: 1)); // Allow overscroll to settle
expect(scrollable.position.pixels, equals(expectedOffset));
}
await testOutOfBounds(const ClampingScrollPhysics(), -400.0, 0.0);
await testOutOfBounds(const ClampingScrollPhysics(), 800.0, 50.0);
});
}