ILSpy/ILSpy.Tests/Options/ThemePickerTests.cs

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using System.Threading.Tasks;

using Avalonia.Headless.NUnit;

using AwesomeAssertions;

using ICSharpCode.ILSpy;
using ICSharpCode.ILSpy.AppEnv;
using ICSharpCode.ILSpy.Options;
using ICSharpCode.ILSpy.Themes;

using NUnit.Framework;

namespace ICSharpCode.ILSpy.Tests;

/// <summary>
/// The Display options page exposes a theme picker bound to SessionSettings.Theme, which switches the
/// theme live (ThemeManager applies it). (Regression: the picker was dropped from the Avalonia panel.)
/// </summary>
[TestFixture]
public class ThemePickerTests
{
	[AvaloniaTest]
	public async Task Display_Options_Theme_Picker_Lists_Themes_And_Switches_Live()
	{
		await TestHarness.BootAsync(1);
		var settingsService = AppComposition.Current.GetExport<SettingsService>();
		var original = settingsService.SessionSettings.Theme;
		try
		{
			var vm = new DisplaySettingsViewModel();
			vm.Load(settingsService);

			vm.AllThemes.Should().Contain("Light").And.Contain("Dark");

			// The picker binds two-way to the live SessionSettings.Theme -- the exact property
			// SetThemeCommand sets and ThemeManager applies, so the picker switches the theme.
			vm.SessionSettings.Should().BeSameAs(settingsService.SessionSettings);
			vm.SessionSettings.Theme = "Dark";
			settingsService.SessionSettings.Theme.Should().Be("Dark");

			vm.LoadDefaults();
			vm.SessionSettings.Theme.Should().Be(ThemeManager.Current.DefaultTheme,
				"resetting Display defaults restores the default theme");
		}
		finally
		{
			settingsService.SessionSettings.Theme = original;
		}
	}
}