Add specific DependencyProperty scenario for NullableBool MarkupExtension tests

(as per original uservoice request for this missing feature)

UnitTests/Extensions/Helpers/ObjectWithNullableBoolProperty.cs

@@ -0,0 +1,31 @@
+// ******************************************************************
+// Copyright (c) Microsoft. All rights reserved.
+// This code is licensed under the MIT License (MIT).
+// THE CODE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH
+// THE CODE OR THE USE OR OTHER DEALINGS IN THE CODE.
+// ******************************************************************
+
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Data;
+
+namespace UnitTests.Extensions.Helpers
+{
+    [Bindable]
+    public class ObjectWithNullableBoolProperty : DependencyObject
+    {
+        public bool? NullableBool
+        {
+            get { return (bool?)GetValue(NullableBoolProperty); }
+            set { SetValue(NullableBoolProperty, value); }
+        }
+
+        // Using a DependencyProperty as the backing store for NullableBool.  This enables animation, styling, binding, etc...
+        public static readonly DependencyProperty NullableBoolProperty =
+            DependencyProperty.Register(nameof(NullableBool), typeof(bool?), typeof(ObjectWithNullableBoolProperty), new PropertyMetadata(null));
+    }
+}

UnitTests/Extensions/Test_NullableBoolMarkupExtension.cs

@@ -10,16 +10,14 @@
 // THE CODE OR THE USE OR OTHER DEALINGS IN THE CODE.
 // ******************************************************************
 
-using Microsoft.Toolkit.Extensions;
 using Microsoft.Toolkit.Uwp.UI.Extensions;
 using Microsoft.VisualStudio.TestPlatform.UnitTestFramework;
 using Microsoft.VisualStudio.TestPlatform.UnitTestFramework.AppContainer;
-using System;
-using System.Diagnostics;
-using System.Linq;
+using UnitTests.Extensions.Helpers;
 using Windows.UI.Xaml;
 using Windows.UI.Xaml.Controls;
 using Windows.UI.Xaml.Markup;
+
 using Assert = Microsoft.VisualStudio.TestPlatform.UnitTestFramework.Assert;
 
 namespace UnitTests.Extensions
@@ -117,5 +115,73 @@ public void Test_NullableBool_MarkupExtension_ProvidesNullStillWithFalseValue()
 
             Assert.AreEqual(null, toggle.IsChecked, "Expected checkbox value to be null.");
         }
+
+        [TestCategory("NullableBoolMarkupExtension")]
+        [UITestMethod]
+        public void Test_NullableBool_Test_TestObject()
+        {
+            // Just test that we can properly parse our object as-is into our test harness.
+            var treeroot = XamlReader.Load(@"<Page
+    xmlns=""http://schemas.microsoft.com/winfx/2006/xaml/presentation""
+    xmlns:x=""http://schemas.microsoft.com/winfx/2006/xaml""
+    xmlns:ex=""using:Microsoft.Toolkit.Uwp.UI.Extensions""
+    xmlns:helpers=""using:UnitTests.Extensions.Helpers"">
+    <Page.Resources>
+        <helpers:ObjectWithNullableBoolProperty x:Key=""OurObject""/>
+    </Page.Resources>
+</Page>") as FrameworkElement;
+
+            var obj = treeroot.Resources["OurObject"] as ObjectWithNullableBoolProperty;
+
+            Assert.IsNotNull(obj, "Could not find object in resources.");
+
+            Assert.AreEqual(null, obj.NullableBool, "Expected obj value to be null.");
+        }
+
+        [TestCategory("NullableBoolMarkupExtension")]
+        [UITestMethod]
+        public void Test_NullableBool_DependencyProperty_SystemTrueValueFails()
+        {
+            // This is the failure case in the OS currently which causes us to need
+            // this markup extension.
+            var exception = Assert.ThrowsException<XamlParseException>(
+                () =>
+            {
+                var treeroot = XamlReader.Load(@"<Page
+    xmlns=""http://schemas.microsoft.com/winfx/2006/xaml/presentation""
+    xmlns:x=""http://schemas.microsoft.com/winfx/2006/xaml""
+    xmlns:ex=""using:Microsoft.Toolkit.Uwp.UI.Extensions""
+    xmlns:helpers=""using:UnitTests.Extensions.Helpers"">
+    <Page.Resources>
+        <helpers:ObjectWithNullableBoolProperty x:Key=""OurObject"" NullableBool=""True""/>
+    </Page.Resources>
+</Page>") as FrameworkElement;
+            }, "Expected assignment failure during parsing, OS now supports, update documentation.");
+
+            Assert.IsNotNull(exception);
+
+            Assert.IsTrue(exception.Message.Contains("Failed to create a 'Windows.Foundation.IReference`1<Boolean>' from the text 'True'."));
+        }
+
+        [TestCategory("NullableBoolMarkupExtension")]
+        [UITestMethod]
+        public void Test_NullableBool_DependencyProperty_TrueValue()
+        {
+            var treeroot = XamlReader.Load(@"<Page
+    xmlns=""http://schemas.microsoft.com/winfx/2006/xaml/presentation""
+    xmlns:x=""http://schemas.microsoft.com/winfx/2006/xaml""
+    xmlns:ex=""using:Microsoft.Toolkit.Uwp.UI.Extensions""
+    xmlns:helpers=""using:UnitTests.Extensions.Helpers"">
+    <Page.Resources>
+        <helpers:ObjectWithNullableBoolProperty x:Key=""OurObject"" NullableBool=""{ex:NullableBool Value=True}""/>
+    </Page.Resources>
+</Page>") as FrameworkElement;
+                
+            var obj = treeroot.Resources["OurObject"] as ObjectWithNullableBoolProperty;
+
+            Assert.IsNotNull(obj, "Could not find object in resources.");
+
+            Assert.AreEqual(true, obj.NullableBool, "Expected obj value to be true.");
+        }
     }
 }