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492b6f7ddf
The documentation for using `findChildIndexCallback` recommends using `indexOf`, but that causes [this line](05259ca938/packages/flutter/lib/src/rendering/sliver_multi_box_adaptor.dart (L259)) to throw in debug mode, and when using `SliverList`, it breaks the render.
This PR changes the usage to check if the index is not negative before using it, and changes to return `null` instead if the child wasn't able to be found.
There's the related issue #107123, but this doesn't actually fix it.
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This PR has been updated to add the snippets that were used in the `findChildIndexCallback` comment as examples with proper tests, as well as updating the comment to reference the new examples.
30 lines
1.1 KiB
Dart
30 lines
1.1 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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import 'package:flutter/material.dart';
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import 'package:flutter_api_samples/widgets/page_view/page_view.1.dart'
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as example;
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import 'package:flutter_test/flutter_test.dart';
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void main() {
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testWidgets(
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'tapping Reverse button should reverse PageView',
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(WidgetTester tester) async {
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await tester.pumpWidget(const example.PageViewExampleApp());
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final Finder pageView = find.byType(PageView);
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final Finder reverseFinder = find.text('Reverse items');
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final Finder firstItemFinder = find.byKey(const ValueKey<String>('1'));
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final Finder lastItemFinder = find.byKey(const ValueKey<String>('5'));
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expect(pageView, findsOneWidget);
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expect(reverseFinder, findsOneWidget);
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expect(firstItemFinder, findsOneWidget);
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expect(lastItemFinder, findsNothing);
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await tester.tap(reverseFinder);
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await tester.pump();
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expect(firstItemFinder, findsNothing);
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expect(lastItemFinder, findsOneWidget);
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},
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);
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}
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