颤振 'tester.scrollUntilVisible' 抛出"Bad state: Too many elements"异常

Question

我有以下元素封装到一个单独的ListView在我的材料应用程序:

home: Scaffold(
appBar: AppBar(title: const Text("Flutter Layout")),
body: ListView(children: [
fibonacciSection,
// a ListView supports app body scrolling when the app is run on a small device.
Image.asset("images/lake.jpg",
width: 600,
height: 240,
fit: BoxFit
.cover), // BoxFit.cover tells the framework that the image should be as small as possible but cover its entire render box.
titleSection,
buttonsSection,
textSection,
statesSection
])));

当我运行包含以下代码片段的单元测试时:

await tester.pumpWidget(const MyApp(key: Key("StateManagemetTests")));
final listFinder = find.byType(Scrollable);
final itemFinder = find.byType(TapboxB);
// Scroll until the item to be found appears.
await tester.scrollUntilVisible(
itemFinder,
500.0,
scrollable: listFinder,
);

抛出以下异常:

══╡ EXCEPTION CAUGHT BY FLUTTER TEST FRAMEWORK ╞════════════════════════════════════════════════════
The following StateError was thrown running a test:
Bad state: Too many elements
When the exception was thrown, this was the stack:
#0      Iterable.single (dart:core/iterable.dart:656:24)
#1      WidgetController.widget (package:flutter_test/src/controller.dart:69:30)
#2      WidgetController.scrollUntilVisible.<anonymous closure> (package:flutter_test/src/controller.dart:1190:15)
#3      WidgetController.scrollUntilVisible.<anonymous closure> (package:flutter_test/src/controller.dart:1188:39)
#6      TestAsyncUtils.guard (package:flutter_test/src/test_async_utils.dart:71:41)
#7      WidgetController.scrollUntilVisible (package:flutter_test/src/controller.dart:1188:27)
#8      main.<anonymous closure> (file:///usr/src/flutter/flutter_app_layout/test/widget_test.dart:50:18)
<asynchronous suspension>
<asynchronous suspension>
(elided 3 frames from dart:async and package:stack_trace)

任何建议和见解是感激的!

Answer 1

当小部件树中有多个Scrollable时，似乎会发生错误。那Flutter就不知道该滚动哪个了。您可以通过首先找到正确的Scrollable并告诉scrollUntilVisible使用它来解决这个问题:

// Scroll Save button into view
final listFinder = find.byType(Scrollable).last; // take last because the tab bar up top is also a Scrollable
expect(listFinder, findsOneWidget);
await tester.scrollUntilVisible(acceptButtonFinder, 100, scrollable: listFinder);

享受吧!

Answer 2

用dragUntilVisible()代替scrollUntilVisible()解决了问题!我根本没有找到scrollUntilVisible()的任何东西。这是一个过时的API，应该从框架中删除吗?