Add VisualTree Tests

Author: michael-hawker

UnitTests/UnitTests.UWP/Extensions/Test_LogicalTreeExtensions.cs

@@ -265,6 +265,45 @@ await App.DispatcherQueue.EnqueueAsync(async () =>
             });
         }
 
+        [TestCategory("LogicalTree")]
+        [TestMethod]
+        public async Task Test_LogicalTree_FindChildren_NotFound()
+        {
+            await App.DispatcherQueue.EnqueueAsync(async () =>
+            {
+                var treeRoot = XamlReader.Load(@"<Page
+    xmlns=""http://schemas.microsoft.com/winfx/2006/xaml/presentation""
+    xmlns:x=""http://schemas.microsoft.com/winfx/2006/xaml""> <!-- Starting Point -->
+    <Grid>
+        <Grid>
+            <Border/>
+            <TextBlock x:Name=""One""/>
+            <StackPanel>
+                <TextBox/>
+                <TextBlock x:Name=""Two""/>
+            </StackPanel>
+        </Grid>
+        <TextBlock x:Name=""Three""/>
+    </Grid>
+</Page>") as Page;
+
+                // Test Setup
+                Assert.IsNotNull(treeRoot, "XAML Failed to Load");
+
+                // Initialize Visual Tree
+                await SetTestContentAsync(treeRoot);
+
+                // Main Test
+                var thing = treeRoot.FindChildren<UniformGrid>();
+
+                Assert.IsNotNull(thing, "Expected to still have enumerable.");
+
+                var array = thing.ToArray();
+
+                Assert.AreEqual(0, array.Length, "Expected to have 0 elements.");
+            });
+        }
+
         [TestCategory("LogicalTree")]
         [TestMethod]
         public async Task Test_LogicalTree_FindParent_Exists()