feat: New DependencyPropertyHelper class

src/Uno.UI.RuntimeTests/Tests/Uno_Helpers/Given_DependencyPropertyHelper.cs

@@ -0,0 +1,259 @@
+#if HAS_UNO // DependencyPropertyHelper is only available on Uno
+#nullable enable
+
+using System;
+using FluentAssertions;
+using FluentAssertions.Execution;
+using Microsoft.UI.Xaml;
+using Microsoft.UI.Xaml.Controls;
+using Uno.UI.Xaml.Core;
+
+namespace Uno.UI.RuntimeTests.Tests.Uno_Helpers;
+
+[TestClass]
+[RunsOnUIThread]
+public partial class Given_DependencyPropertyHelper
+{
+	[TestMethod]
+	public void When_GetDefaultValue()
+	{
+		// Arrange
+		var property = TestClass.TestProperty;
+
+		// Act
+		var defaultValue = DependencyPropertyHelper.GetDefaultValue(property);
+
+		// Assert
+		defaultValue.Should().Be("TestValue");
+	}
+
+	[TestMethod]
+	public void When_GetDependencyPropertyByName_OwnerType()
+	{
+		// Arrange
+		var propertyName = "TestProperty";
+
+		// Act
+		var property1 = DependencyPropertyHelper.GetDependencyPropertyByName(typeof(TestClass), propertyName);
+		var property2 = DependencyPropertyHelper.GetDependencyPropertyByName(typeof(DerivedTestClass), propertyName);
+
+		// Assert
+		property1.Should().Be(TestClass.TestProperty);
+		property2.Should().Be(TestClass.TestProperty);
+	}
+
+	[TestMethod]
+	public void When_GetDependencyPropertyByName_Property()
+	{
+		// Arrange
+		var propertyName = "TestProperty";
+
+		// Act
+		var property1 = DependencyPropertyHelper.GetDependencyPropertyByName<TestClass>(propertyName);
+		var property2 = DependencyPropertyHelper.GetDependencyPropertyByName<TestClass>(propertyName);
+
+		// Assert
+		property1.Should().Be(TestClass.TestProperty);
+		property2.Should().Be(TestClass.TestProperty);
+	}
+
+	[TestMethod]
+	public void When_GetDependencyPropertyByName_InvalidProperty()
+	{
+		// Arrange
+		var propertyName = "InvalidProperty";
+
+		// Act
+		var property = DependencyPropertyHelper.GetDependencyPropertyByName(typeof(TestClass), propertyName);
+
+		// Assert
+		property.Should().BeNull();
+	}
+
+	[TestMethod]
+	public void When_GetDependencyPropertyByName_InvalidPropertyCasing()
+	{
+		// Arrange
+		var propertyName = "testProperty";
+
+		// Act
+		var property = DependencyPropertyHelper.GetDependencyPropertyByName(typeof(TestClass), propertyName);
+
+		// Assert
+		property.Should().BeNull();
+	}
+
+	[TestMethod]
+	public void When_GetDependencyPropertiesForType()
+	{
+		// Arrange
+		var properties = DependencyPropertyHelper.GetDependencyPropertiesForType<TestClass>();
+
+		// Assert
+		properties.Should().Contain(TestClass.TestProperty);
+	}
+
+	[TestMethod]
+	public void When_TryGetDependencyPropertiesForType()
+	{
+		// Arrange
+		var success = DependencyPropertyHelper.TryGetDependencyPropertiesForType(typeof(TestClass), out var properties);
+
+		// Assert
+		success.Should().BeTrue();
+		properties.Should().Contain(TestClass.TestProperty);
+	}
+
+	[TestMethod]
+	public void When_TryGetDependencyPropertiesForType_Invalid()
+	{
+		// Arrange
+		var success = DependencyPropertyHelper.TryGetDependencyPropertiesForType(typeof(string), out var properties);
+
+		// Assert
+		success.Should().BeFalse();
+		properties.Should().BeNull();
+	}
+
+	[TestMethod]
+	public void When_GetPropertyType()
+	{
+		// Arrange
+		var property = TestClass.TestProperty;
+
+		// Act
+		var propertyType = DependencyPropertyHelper.GetValueType(property);
+
+		// Assert
+		propertyType.Should().Be(typeof(string));
+	}
+
+	[TestMethod]
+	public void When_GetPropertyDetails()
+	{
+		// Arrange
+		var property = TestClass.TestProperty;
+
+		// Act
+		var (valueType, ownerType, name, isTypeNullable, isAttached, inInherited, defaultValue) = DependencyPropertyHelper.GetDetails(property);
+
+		// Assert
+		using var _ = new AssertionScope();
+		valueType.Should().Be(typeof(string));
+		ownerType.Should().Be(typeof(TestClass));
+		name.Should().Be("TestProperty");
+		isTypeNullable.Should().BeTrue();
+		isAttached.Should().BeFalse();
+		inInherited.Should().BeFalse();
+		defaultValue.Should().Be("TestValue");
+	}
+
+	[TestMethod]
+	public void When_GetPropertyDetails_DataContext()
+	{
+		// Arrange
+		var property = UIElement.DataContextProperty;
+
+		// Act
+		var (valueType, _, name, isTypeNullable, isAttached, inInherited, defaultValue) = DependencyPropertyHelper.GetDetails(property);
+
+		// Assert
+		using var _ = new AssertionScope();
+		valueType.Should().Be(typeof(object));
+		// ownerType is not checked here because it's different following the platform
+		name.Should().Be("DataContext");
+		isTypeNullable.Should().BeTrue();
+		isAttached.Should().BeFalse();
+		inInherited.Should().BeTrue();
+		defaultValue.Should().BeNull();
+	}
+
+	[TestMethod]
+	public void When_GetPropertyDetails_Attached()
+	{
+		// Arrange
+		var property = Grid.RowProperty;
+
+		// Act
+		var (valueType, ownerType, name, isTypeNullable, isAttached, inInherited, defaultValue) = DependencyPropertyHelper.GetDetails(property);
+
+		// Assert
+		using var _ = new AssertionScope();
+		valueType.Should().Be(typeof(int));
+		ownerType.Should().Be(typeof(Grid));
+		name.Should().Be("Row");
+		isTypeNullable.Should().BeFalse();
+		isAttached.Should().BeTrue();
+		inInherited.Should().BeFalse();
+		defaultValue.Should().Be(0);
+	}
+
+	[TestMethod]
+	public void When_GetProperties()
+	{
+		var properties = DependencyPropertyHelper.GetDependencyPropertiesForType<DerivedTestClass>();
+
+		properties.Should().Contain(DerivedTestClass.TestProperty);
+	}
+
+	[TestMethod]
+	public void When_GetDefaultValue_Derived()
+	{
+		// Arrange
+		var property = DerivedTestClass.TestProperty;
+
+		// Act
+		var defaultValue = DependencyPropertyHelper.GetDefaultValue(property);
+
+		// Assert
+		defaultValue.Should().Be("TestValue");
+	}
+
+	[TestMethod]
+	public void When_GetDefaultUnsetValue_FromStyle()
+	{
+		// Arrange
+		var sut = new DerivedTestClass();
+		sut.SetValue(TestClass.TestProperty, "Something");
+
+		// Act
+		var (unsetValue, precedence) = DependencyPropertyHelper.GetDefaultUnsetValue(sut, TestClass.TestProperty);
+
+		// Assert
+		unsetValue.Should().Be("StyledTestValue");
+		precedence.Should().Be(DependencyPropertyValuePrecedences.ExplicitStyle);
+	}
+
+	[TestMethod]
+	public void When_GetDefaultUnsetValue()
+	{
+		// Arrange
+		var sut = new TestClass();
+		sut.SetValue(TestClass.TestProperty, "Something");
+
+		// Act
+		var (unsetValue, precedence) = DependencyPropertyHelper.GetDefaultUnsetValue(sut, TestClass.TestProperty);
+
+		// Assert
+		unsetValue.Should().Be("TestValue");
+		precedence.Should().Be(DependencyPropertyValuePrecedences.DefaultValue);
+	}
+
+
+	private partial class TestClass : FrameworkElement // Not a DependencyObject because we don't want to deal with the generator here
+	{
+		public static readonly DependencyProperty TestProperty = DependencyProperty.Register("TestProperty", typeof(string), typeof(TestClass), new PropertyMetadata("TestValue"));
+	}
+
+	private partial class DerivedTestClass : TestClass
+	{
+		public DerivedTestClass()
+		{
+			Style = new Style(typeof(DerivedTestClass))
+			{
+				Setters = { new Setter(TestProperty, "StyledTestValue") }
+			};
+		}
+	}
+}
+#endif

src/Uno.UI/UI/Xaml/DependencyObjectStore.cs

@@ -447,9 +447,7 @@ public void SetValue(DependencyProperty property, object value)
 		/// <summary>
 		/// Clears the value for the specified dependency property on the specified instance.
 		/// </summary>
-		/// <param name="instance">The instance on which the property is attached</param>
 		/// <param name="property">The dependency property to get</param>
-		/// <param name="precedence">The value precedence to assign</param>
 		public void ClearValue(DependencyProperty property)
 		{
 			SetValue(property, DependencyProperty.UnsetValue, DependencyPropertyValuePrecedences.Local);