Center the update count text inside the sidebar badge

src/UniGetUI.Avalonia/Views/SidebarView.axaml

@@ -97,7 +97,7 @@
                                    FontSize="9"
                                    FontWeight="Bold"
                                    Foreground="{DynamicResource TextOnAccentFillColorPrimaryBrush}"
-                                   HorizontalAlignment="Center"
+                                   TextAlignment="Center"
                                    VerticalAlignment="Center"/>
                     </Border>
                     <ProgressBar IsIndeterminate="{Binding UpdatesIsLoading}"

src/UniGetUI.Tests/SidebarUpdateBadgeTests.cs

@@ -0,0 +1,69 @@
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Headless;
+using Avalonia.Media.TextFormatting;
+using Avalonia.Themes.Fluent;
+using Avalonia.Threading;
+using Avalonia.VisualTree;
+using UniGetUI.Avalonia.ViewModels;
+using UniGetUI.Avalonia.Views;
+using UniGetUI.Core.Data;
+using CoreSettings = UniGetUI.Core.SettingsEngine.Settings;
+
+namespace UniGetUI.Tests;
+
+public sealed class SidebarUpdateBadgeTests : IDisposable
+{
+    private readonly HeadlessUnitTestSession _session =
+        HeadlessUnitTestSession.GetOrStartForAssembly(typeof(SidebarUpdateBadgeTests).Assembly);
+    private readonly string _testRoot = Path.Combine(Path.GetTempPath(), nameof(SidebarUpdateBadgeTests), Guid.NewGuid().ToString("N"));
+
+    public SidebarUpdateBadgeTests()
+    {
+        CoreData.TEST_DataDirectoryOverride = Path.Combine(_testRoot, "Data");
+        Directory.CreateDirectory(CoreData.UniGetUIUserConfigurationDirectory);
+        CoreSettings.ResetSettings();
+    }
+
+    public void Dispose()
+    {
+        CoreSettings.ResetSettings();
+        CoreData.TEST_DataDirectoryOverride = null;
+        Directory.Delete(_testRoot, recursive: true);
+    }
+
+    [Theory]
+    [InlineData(3, 1.0)]
+    [InlineData(3, 1.25)]
+    [InlineData(3, 2.0)]
+    [InlineData(42, 1.0)]
+    [InlineData(42, 1.5)]
+    [InlineData(150, 1.0)]
+    [InlineData(150, 2.0)]
+    public Task UpdateCountIsHorizontallyCenteredInItsBadge(int count, double scaling) => _session.Dispatch(() =>
+    {
+        if (!Application.Current!.Styles.OfType<FluentTheme>().Any())
+            Application.Current.Styles.Add(new FluentTheme());
+
+        var vm = new SidebarViewModel { UpdatesBadgeCount = count };
+        var view = new SidebarView { DataContext = vm };
+        var window = new Window { Width = 300, Height = 700, Content = view };
+        window.SetRenderScaling(scaling);
+        window.Show();
+        window.UpdateLayout();
+        Dispatcher.UIThread.RunJobs();
+
+        ListBoxItem updates = view.FindControl<ListBox>("NavListBox")!.Items.OfType<ListBoxItem>()
+            .Single(item => (string?)item.Tag == "Updates");
+        TextBlock text = updates.GetVisualDescendants().OfType<TextBlock>().Single(block => block.Text == vm.UpdatesBadgeText);
+        var badge = (Border)text.Parent!;
+        TextLine line = text.TextLayout.TextLines.Single();
+
+        double textLeft = text.TranslatePoint(new Point(line.Start, 0), badge)!.Value.X;
+        double textRight = textLeft + line.WidthIncludingTrailingWhitespace;
+
+        Assert.True(badge.IsEffectivelyVisible);
+        Assert.Equal(badge.Bounds.Width - textRight, textLeft, 0.01);
+        window.Close();
+    }, CancellationToken.None);
+}