UI test for #1986

samples/AvaloniaSample/VisualTest/VirtualizationTest/View.axaml

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+<UserControl
+    x:Class="AvaloniaSample.VisualTest.VirtualizationTest.View"
+    xmlns="https://github.com/avaloniaui"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:lvc="using:LiveChartsCore.SkiaSharpView.Avalonia">
+
+    <TabControl x:Name="tabs">
+        <TabItem Header="page 1">
+            <ScrollViewer>
+                <StackPanel Orientation="Vertical">
+                    <Rectangle Height="3000" Width="100" Fill="Red"/>
+                    <lvc:CartesianChart x:Name="chart1" Height="300">
+                        <lvc:CartesianChart.Series>
+                            <lvc:XamlLineSeries
+                                SeriesName="Mary"
+                                Values="{lvc:Values FromString='5, 10, 8, 4'}"/>
+                            <lvc:XamlColumnSeries
+                                SeriesName="Ana"
+                                Values="{lvc:Values FromString='4, 7, 3, 8'}"/>
+                        </lvc:CartesianChart.Series>
+                    </lvc:CartesianChart>
+                </StackPanel>
+            </ScrollViewer>
+        </TabItem>
+        <TabItem Header="page 2">
+            <ScrollViewer>
+                <StackPanel Orientation="Vertical">
+                    <Rectangle Height="3000" Width="100" Fill="Red"/>
+                    <lvc:CartesianChart x:Name="chart2" Height="300">
+                        <lvc:CartesianChart.Series>
+                            <lvc:XamlLineSeries
+                                SeriesName="Mary"
+                                Values="{lvc:Values FromString='5, 10, 8, 4'}"/>
+                            <lvc:XamlColumnSeries
+                                SeriesName="Ana"
+                                Values="{lvc:Values FromString='4, 7, 3, 8'}"/>
+                        </lvc:CartesianChart.Series>
+                    </lvc:CartesianChart>
+                </StackPanel>
+            </ScrollViewer>
+        </TabItem>
+    </TabControl>
+
+</UserControl>

samples/AvaloniaSample/VisualTest/VirtualizationTest/View.axaml.cs

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+using Avalonia.Controls;
+using Avalonia.Markup.Xaml;
+using LiveChartsCore.SkiaSharpView.Avalonia;
+
+namespace AvaloniaSample.VisualTest.VirtualizationTest;
+
+public partial class View : UserControl
+{
+    public View()
+    {
+        InitializeComponent();
+    }
+
+    public CartesianChart Chart1 => this.Find<CartesianChart>("chart1")!;
+    public CartesianChart Chart2 => this.Find<CartesianChart>("chart2")!;
+    public void OpenTab1() => this.Find<TabControl>("tabs")!.SelectedIndex = 0;
+    public void OpenTab2() => this.Find<TabControl>("tabs")!.SelectedIndex = 1;
+    public void ScrollToChart() => ((ScrollViewer)this.Find<TabControl>("tabs")!.SelectedContent!).ScrollToEnd();
+
+    private void InitializeComponent()
+    {
+        AvaloniaXamlLoader.Load(this);
+    }
+}

tests/SharedUITests/AvaloniaTests.cs

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+#if AVALONIA_UI_TESTING
+
+using Factos;
+using SharedUITests.Helpers;
+using Xunit;
+
+namespace SharedUITests;
+
+public class AvaloniaTests
+{
+    public AppController App => AppController.Current;
+
+    // based on:
+    // https://github.com/Live-Charts/LiveCharts2/issues/1986
+    // ensure charts load when avalonia virtualization is on.
+    [AppTestMethod]
+    public async Task TabControlScrollViewerRendersAfterTabSwitch()
+    {
+        var sut = await App.NavigateTo<Samples.VisualTest.VirtualizationTest.View>();
+
+        // open the second tab, scroll to end and ensure the chart is loaded.
+        sut.OpenTab2();
+        await Task.Delay(1000);
+        sut.ScrollToChart();
+        await Task.Delay(1000);
+        Assert.ChartIsLoaded(sut.Chart2);
+
+        // now open the first tab, scroll to end and ensure the chart is loaded.
+        sut.OpenTab1();
+        await Task.Delay(1000);
+        sut.ScrollToChart();
+        await Task.Delay(1000);
+        Assert.ChartIsLoaded(sut.Chart1);
+    }
+}
+
+#endif