[Windows] Add scrolling tests for virtualization w/ Datatemplates (#2…

…0954)

* Add tests for scrolling w/ datatemplates

* Forgot csproj

* Add tests for scroll virtualization

* Revert

* Adjust ref image

* Ensure items get hydrated before screenshot verify

---------

Co-authored-by: Mike Corsaro <[email protected]>

src/Controls/samples/Controls.Sample.UITests/Issues/Issue20842.xaml

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+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             x:Class="Maui.Controls.Sample.Issues.Issue20842"
+             xmlns:local="clr-namespace:Maui.Controls.Sample.Issues"
+             Background="White">
+    <ContentPage.Resources>
+        <DataTemplate x:Key="validPersonTemplate">
+            <Grid>
+                <Grid.ColumnDefinitions>
+                    <ColumnDefinition Width="0.4*" />
+                    <ColumnDefinition Width="0.3*" />
+                    <ColumnDefinition Width="0.3*" />
+                </Grid.ColumnDefinitions>
+                <Label Text="{Binding Name}"
+                       TextColor="Green"
+                       FontAttributes="Bold" />
+                <Label Grid.Column="1"
+                       Text="{Binding DateOfBirth, StringFormat='{0:d}'}"
+                       TextColor="Green" />
+                <Label Grid.Column="2"
+                       Text="{Binding Location}"
+                       TextColor="Green"
+                       HorizontalTextAlignment="End" />
+            </Grid>
+        </DataTemplate>
+        <DataTemplate x:Key="invalidPersonTemplate">
+            <Grid>
+                <Grid.ColumnDefinitions>
+                    <ColumnDefinition Width="0.4*" />
+                    <ColumnDefinition Width="0.3*" />
+                    <ColumnDefinition Width="0.3*" />
+                </Grid.ColumnDefinitions>
+                <Label Text="{Binding Name}"
+                       TextColor="Red"
+                       FontAttributes="Bold" />
+                <Label Grid.Column="1"
+                       Text="{Binding DateOfBirth, StringFormat='{0:d}'}"
+                       TextColor="Red" />
+                <Label Grid.Column="2"
+                       Text="{Binding Location}"
+                       TextColor="Red"
+                       HorizontalTextAlignment="End" />
+            </Grid>
+        </DataTemplate>
+        <local:PersonDataTemplateSelector x:Key="personDataTemplateSelector"
+                                          ValidTemplate="{StaticResource validPersonTemplate}"
+                                          InvalidTemplate="{StaticResource invalidPersonTemplate}" />
+    </ContentPage.Resources>
+
+    <VerticalStackLayout>
+        <CollectionView
+            x:Name="PersonList"
+            HeightRequest="400"
+            ItemTemplate="{StaticResource personDataTemplateSelector}"/>
+
+        <Button
+            Text="Scroll To Top"
+            Clicked="ScrollToTopButton_Clicked"
+            x:Name="ScrollUpButton"
+            AutomationId="ScrollUpButton"/>
+
+        <Button
+            Text="Scroll To Bottom"
+            Clicked="ScrollToBottomButton_Clicked"
+            x:Name="ScrollDownButton"
+            AutomationId="ScrollDownButton"/>
+    </VerticalStackLayout>
+</ContentPage>

src/Controls/samples/Controls.Sample.UITests/Issues/Issue20842.xaml.cs

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+using System;
+using System.Collections.Generic;
+using Microsoft.Maui.Controls;
+
+namespace Maui.Controls.Sample.Issues
+{
+	internal class Person
+	{
+		public string Name { get; set; } = "";
+		public int Age { get; set; }
+		public DateTime DateOfBirth { get; set; }
+		public string Location { get; set; } = "";
+
+		public override string ToString()
+			=> Name;
+	}
+
+	public class PersonDataTemplateSelector : DataTemplateSelector
+	{
+		public required DataTemplate ValidTemplate { get; set; }
+		public required DataTemplate InvalidTemplate { get; set; }
+
+		protected override DataTemplate OnSelectTemplate(object item, BindableObject container)
+		{
+			return ((Person)item).DateOfBirth.Year >= 1980 ? ValidTemplate : InvalidTemplate;
+		}
+	}
+
+	[Issue(IssueTracker.Github, "20842", "Verify data templates in CollectionView virtualize correctly", PlatformAffected.UWP)]
+	public partial class Issue20842 : ContentPage
+	{
+		private readonly List<Person> people = new();
+
+		public Issue20842()
+		{
+			InitializeComponent();
+
+			for (int i = 0; i < 100; i++)
+			{
+				people.Add(new Person { Name = $"Kath {i}", DateOfBirth = new DateTime(1985, 11, 20), Location = "France" });
+				people.Add(new Person { Name = $"Steve {i}", DateOfBirth = new DateTime(1975, 1, 15), Location = "USA" });
+				people.Add(new Person { Name = $"Lucas {i}", DateOfBirth = new DateTime(1988, 2, 5), Location = "Germany" });
+				people.Add(new Person { Name = $"John {i}", DateOfBirth = new DateTime(1976, 2, 20), Location = "USA" });
+				people.Add(new Person { Name = $"Tariq {i}", DateOfBirth = new DateTime(1987, 1, 10), Location = "UK" });
+				people.Add(new Person { Name = $"Jane {i}", DateOfBirth = new DateTime(1982, 8, 30), Location = "USA" });
+				people.Add(new Person { Name = $"Tom {i}", DateOfBirth = new DateTime(1977, 3, 10), Location = "UK" });
+			}
+
+			PersonList.ItemsSource = people;
+		}
+
+		private void ScrollToTopButton_Clicked(object sender, EventArgs e)
+		{
+			PersonList.ScrollTo(0, animate: false);
+		}
+
+		private void ScrollToBottomButton_Clicked(object sender, EventArgs e)
+		{
+			PersonList.ScrollTo(people.Count - 1, animate: false);
+		}
+	}
+}

src/Controls/tests/UITests/Tests/Issues/Issue20842.cs

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+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.AppiumTests.Issues
+{
+	public class Issue20842 : _IssuesUITest
+	{
+		const string scrollUpButton = "ScrollUpButton";
+		const string scrollDownButton = "ScrollDownButton";
+
+		public Issue20842(TestDevice device) : base(device)
+		{
+		}
+
+		public override string Issue => "Verify data templates in CollectionView virtualize correctly";
+
+		[Test]
+		public async Task VerifyCollectionViewItemsAfterScrolling()
+		{
+			this.IgnoreIfPlatforms([TestDevice.Android, TestDevice.iOS, TestDevice.Mac]);
+
+			App.WaitForElement(scrollUpButton);
+
+			App.Click(scrollDownButton);
+			await Task.Delay(200);
+			App.Click(scrollUpButton);
+			await Task.Delay(200);
+			App.Click(scrollDownButton);
+   			await Task.Delay(500);
+
+			VerifyScreenshot();
+		}
+	}
+}
+