Flutter:如何测试滚动 [英] Flutter: how to test the scroll

问题描述

我有一个以 ScrollController 作为控制器的 ListView.builder:

I have a ListView.builder with a ScrollController as controller:

  _buildListView(state) => ListView.builder(
        itemBuilder: (_, int index) => _draw(index, state),
        itemCount: state.count
        controller: _scrollController,
      );

我向控制器添加了一个监听器:

I add a listener to the controller:

  View() {
    _scrollController.addListener(_onScroll);
  }

我想测试 _onScroll 函数:

I would like to test the _onScroll function:

 void _onScroll() {
    final maxScroll = _scrollController.position.maxScrollExtent;
    final currentScroll = _scrollController.position.pixels;
    if (maxScroll - currentScroll <= _scrollThreshold) {
      _bloc.dispatch(Fetch());
    }
  }

但我不知道如何测试它.这是我到目前为止尝试过的:

But I don't know how can I test it. This is what I tried so far:

  testWidgets('Should test the scroll',
      (WidgetTester tester) async {
await tester.pumpWidget(generateApp());
    await tester.pump();
    await tester.drag(find.byType(ListView), const Offset(0.0, -300));
    await tester.pump();
...

)}

但它根本不调用那个函数.

but it doesn't call at all that function.

推荐答案

你可以创建一个 TestGesture 在您的测试中并以这种方式执行滚动.

You can create a TestGesture in your tests and perform a scroll that way.

final gesture = await tester.startGesture(Offset(0, 300)); //Position of the scrollview
await gesture.moveBy(Offset(0, -300)); //How much to scroll by
await tester.pump();

这篇关于Flutter:如何测试滚动的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！