Add Style<T> Constructor Overload

src/CommunityToolkit.Maui.Markup.UnitTests/ApplicationTestHelpers.cs

@@ -1,4 +1,5 @@
-namespace CommunityToolkit.Maui.Markup.UnitTests;
+using CommunityToolkit.Maui.Markup.UnitTests.Mocks;
+namespace CommunityToolkit.Maui.Markup.UnitTests;
 
 public static class ApplicationTestHelpers
 {
@@ -11,19 +12,28 @@ public static class ApplicationTestHelpers
 	public static void PerformAppThemeBasedTest<TBindable>(
 		AppTheme appTheme,
 		Func<TBindable> setAppThemeValue,
-		Action<TBindable> assertResult) where TBindable : BindableObject
+		Action<TBindable> assertResult) where TBindable : View
 	{
 		try
 		{
-			_ = new Application();
+			var appBuilder = MauiApp.CreateBuilder()
+				.UseMauiCommunityToolkit()
+				.UseMauiApp<MockApplication>();
 
-			var bindable = setAppThemeValue();
+			var mauiApp = appBuilder.Build();
 
-			var current = Application.Current;
+			var application = mauiApp.Services.GetRequiredService<IApplication>();
+
+			var bindable = setAppThemeValue();
 
-			ArgumentNullException.ThrowIfNull(current);
+			ArgumentNullException.ThrowIfNull(Application.Current);
+
+			Application.Current.MainPage = new ContentPage
+			{
+				Content = bindable
+			};
 
-			current.UserAppTheme = appTheme;
+			Application.Current.UserAppTheme = appTheme;
 
 			assertResult.Invoke(bindable);
 		}

src/CommunityToolkit.Maui.Markup.UnitTests/Mocks/MockApplication.cs

@@ -0,0 +1,29 @@
+using Microsoft.Maui.Controls.Internals;
+using Microsoft.Maui.Handlers;
+
+namespace CommunityToolkit.Maui.Markup.UnitTests.Mocks;
+
+class MockApplication : Application, IPlatformApplication
+{
+	public MockApplication(IServiceProvider serviceProvider)
+	{
+		Services = serviceProvider;
+#pragma warning disable CS0612 // Type or member is obsolete
+		DependencyService.Register<ISystemResourcesProvider, MockResourcesProvider>();
+#pragma warning restore CS0612 // Type or member is obsolete
+	}
+
+	public IApplication Application => this;
+	public IServiceProvider Services { get; }
+}
+
+// Inspired by https://github.com/dotnet/maui/blob/main/src/Controls/tests/Core.UnitTests/TestClasses/ApplicationHandlerStub.cs
+class ApplicationHandlerStub() : ElementHandler<IApplication, object>(Mapper)
+{
+	public static IPropertyMapper<IApplication, ApplicationHandlerStub> Mapper = new PropertyMapper<IApplication, ApplicationHandlerStub>(ElementMapper);
+
+	protected override object CreatePlatformElement()
+	{
+		return new object();
+	}
+}

src/CommunityToolkit.Maui.Markup.UnitTests/Mocks/MockResourcesProvider.cs

@@ -0,0 +1,15 @@
+using Microsoft.Maui.Controls.Internals;
+
+namespace CommunityToolkit.Maui.Markup.UnitTests.Mocks;
+
+
+// Inspired by https://github.com/dotnet/maui/blob/79695fbb7ba6517a334c795ecf0a1d6358ef309a/src/Controls/Foldable/test/MockPlatformServices.cs#L145-L176
+
+#pragma warning disable CS0612 // Type or member is obsolete
+class MockResourcesProvider : ISystemResourcesProvider
+#pragma warning restore CS0612 // Type or member is obsolete
+{
+	readonly ResourceDictionary dictionary = new();
+
+	public IResourceDictionary GetSystemResources() => dictionary;
+}

src/CommunityToolkit.Maui.Markup.UnitTests/StyleTests.cs

@@ -7,7 +7,36 @@ namespace CommunityToolkit.Maui.Markup.UnitTests;
 class StyleTests : BaseMarkupTestFixture
 {
 	[Test]
-	public void ImplicitCast()
+	public void ImplicitCastToStyleT()
+	{
+		var formsStyle = new Style(typeof(Label));
+		var style = (Style<Label>)formsStyle;
+
+		Assert.That(ReferenceEquals(style.MauiStyle, formsStyle));
+	}
+
+	[Test]
+	public void ImplicitCastToStyleTUsingBaseClass()
+	{
+		var formsStyle = new Style(typeof(Label))
+		{
+			Behaviors =
+			{
+				new LabelBehavior()
+			}
+		};
+
+		var style = (Style<View>)formsStyle;
+
+		Assert.Multiple(() =>
+		{
+			Assert.That(formsStyle.Behaviors[0], Is.InstanceOf<LabelBehavior>());
+			Assert.That(style.MauiStyle.Behaviors[0], Is.InstanceOf<LabelBehavior>());
+		});
+	}
+
+	[Test]
+	public void ImplicitCastFromStyleT()
 	{
 		Style<Label> style = new();
 		Style formsStyle = style;
@@ -248,12 +277,15 @@ public void Fluent()
 	[TestCase(AppTheme.Unspecified)]
 	public void AddAppThemeBindingCorrectlySetsPropertyToChangeBasedOnApplicationsAppTheme(AppTheme appTheme)
 	{
-		var expectedColor = appTheme == AppTheme.Dark ? Colors.Orange : Colors.Purple;
+		var darkThemeColor = Colors.Orange;
+		var otherThemeColor = Colors.Purple;
+
+		var expectedColor = appTheme == AppTheme.Dark ? darkThemeColor : otherThemeColor;
 
 		ApplicationTestHelpers.PerformAppThemeBasedTest(
 			appTheme,
 			() => new Label()
-					.Style(new Style<Label>().AddAppThemeBinding(Label.TextColorProperty, Colors.Purple, Colors.Orange))
+					.Style(new Style<Label>().AddAppThemeBinding(Label.TextColorProperty, otherThemeColor, darkThemeColor))
 					.AppThemeBinding(Label.TextProperty, nameof(AppTheme.Light), nameof(AppTheme.Dark)),
 			(label) => Assert.That(label.TextColor, Is.EqualTo(expectedColor)));
 	}
@@ -263,13 +295,16 @@ public void AddAppThemeBindingCorrectlySetsPropertyToChangeBasedOnApplicationsAp
 	[TestCase(AppTheme.Unspecified)]
 	public void AddAppThemeBindingsCorrectlySetsPropertiesToChangeBasedOnApplicationsAppTheme(AppTheme appTheme)
 	{
-		var expectedColor = appTheme == AppTheme.Dark ? Colors.Orange : Colors.Purple;
+		var darkThemeColor = Colors.Orange;
+		var otherThemeColor = Colors.Purple;
+
+		var expectedColor = appTheme == AppTheme.Dark ? darkThemeColor : otherThemeColor;
 		var expectedText = appTheme == AppTheme.Dark ? nameof(AppTheme.Dark) : nameof(AppTheme.Light);
 
 		ApplicationTestHelpers.PerformAppThemeBasedTest(
 			appTheme,
 			() => new Label()
-					.Style(new Style<Label>().AddAppThemeBindings((Label.TextColorProperty, Colors.Purple, Colors.Orange),
+					.Style(new Style<Label>().AddAppThemeBindings((Label.TextColorProperty, otherThemeColor, darkThemeColor),
 													(Label.TextProperty, nameof(AppTheme.Light), nameof(AppTheme.Dark))))
 					.AppThemeBinding(Label.TextProperty, nameof(AppTheme.Light), nameof(AppTheme.Dark)),
 			(label) =>
@@ -282,5 +317,29 @@ public void AddAppThemeBindingsCorrectlySetsPropertiesToChangeBasedOnApplication
 			});
 	}
 
-	class LabelBehavior : Behavior<Label> { }
+	[Test]
+	public void InvalidMauiStyleInitializationShouldThrowException()
+	{
+		var buttonStyle = new Style(typeof(Button));
+		Assert.Throws<ArgumentException>(() => new Style<Label>(buttonStyle));
+	}
+
+	[Test]
+	public void InvalidMauiStyleCastShouldThrowException()
+	{
+		var buttonStyle = new Style(typeof(Button));
+		Assert.Throws<ArgumentException>(() =>
+		{
+			var style = (Style<Label>)buttonStyle;
+		});
+	}
+
+	[Test]
+	public void ValidMauiStyleInitializationDoesNotThrowException()
+	{
+		var buttonStyle = new Style(typeof(Button));
+		Assert.DoesNotThrow(() => new Style<Button>(buttonStyle));
+	}
+
+	class LabelBehavior : Behavior<Label>;
 }

src/CommunityToolkit.Maui.Markup/Style.cs

@@ -7,15 +7,22 @@
 public class Style<T> where T : BindableObject
 {
 	/// <summary>
-	/// FormsStyle
+	/// Converts <see cref="CommunityToolkit.Maui.Markup.Style{T}"/> to <see cref="Microsoft.Maui.Controls.Style"/>
 	/// </summary>
 	/// <param name="style"></param>
 	public static implicit operator Style(Style<T> style) => style.MauiStyle;
 
+	/// <summary>
+	/// Converts <see cref="Microsoft.Maui.Controls.Style"/> to <see cref="CommunityToolkit.Maui.Markup.Style{T}"/>
+	/// </summary>
+	/// <param name="style"></param>
+	/// <returns></returns>
+	public static implicit operator Style<T>(Style style) => new(style);
+
 	/// <summary>
 	/// Initialize Style
 	/// </summary>
-	/// <param name="property">"The <see cref="BindableProperty"/> to style </param>
+	/// <param name="property">"The <see cref="BindableProperty"/> to mauiStyle </param>
 	/// <param name="value">"The value for the <see cref="BindableProperty"/> </param>
 	public Style(BindableProperty property, object value) : this((property, value))
 	{
@@ -32,6 +39,20 @@ public Style(params (BindableProperty Property, object Value)[] setters)
 		Add(setters);
 	}
 
+	/// <summary>
+	/// Initialize Style
+	/// </summary>
+	/// <param name="mauiStyle"></param>
+	public Style(Style mauiStyle)
+	{
+		if (!mauiStyle.TargetType.IsAssignableTo(typeof(T)))
+		{
+			throw new ArgumentException($"Invalid type. The Type used in {nameof(mauiStyle)}.{nameof(mauiStyle.TargetType)} ({mauiStyle.TargetType.FullName}) must be assignable to the Type used in {nameof(Style<T>)} ({typeof(T).FullName})", nameof(mauiStyle));
+		}
+
+		MauiStyle = mauiStyle;
+	}
+
 	/// <summary>
 	/// Style(typeof(T))
 	/// </summary>
@@ -62,7 +83,7 @@ public Style<T> BasedOn(Style value)
 	/// <summary>
 	/// Add Setters
 	/// </summary>
-	/// <param name="property">"The <see cref="BindableProperty"/> to style </param>
+	/// <param name="property">"The <see cref="BindableProperty"/> to mauiStyle </param>
 	/// <param name="value">"The value for the <see cref="BindableProperty"/> </param>
 	/// <returns>Style with added setters</returns>
 	public Style<T> Add(BindableProperty property, object value)
@@ -89,13 +110,17 @@ public Style<T> Add(params (BindableProperty Property, object Value)[] setters)
 	/// <summary>
 	/// Adds the supplied <paramref name="light"/> and <paramref name="dark"/> values in an <see cref="AppThemeBinding"/>.
 	/// </summary>
-	/// <param name="property">"The <see cref="BindableProperty"/> to style </param>
+	/// <param name="property">"The <see cref="BindableProperty"/> to mauiStyle </param>
 	/// <param name="light">"The light value for the <see cref="BindableProperty"/> </param>
 	/// <param name="dark">"The dark value for the <see cref="BindableProperty"/> </param>
 	/// <returns>Style with added setters</returns>
 	public Style<T> AddAppThemeBinding(BindableProperty property, object light, object dark)
 	{
-		MauiStyle.Setters.Add(property, new AppThemeBinding { Light = light, Dark = dark });
+		MauiStyle.Setters.Add(property, new AppThemeBinding
+		{
+			Light = light,
+			Dark = dark
+		});
 		return this;
 	}