Fix formatted text text type crash (#13532)

* Add test file for label causing app crash

* Add checks to prevent app crash

* Add relevant unit test

* - add label to stack layout

* - just call layout directly

* Remove UITest

redundant since we already have unit test

Co-authored-by: Shane Neuville <shneuvil@microsoft.com>

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/LabelFormattedTextHtmlPadding.cs

@@ -0,0 +1,46 @@
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+
+#if UITEST
+using Xamarin.Forms.Core.UITests;
+using Xamarin.UITest;
+using NUnit.Framework;
+#endif
+
+namespace Xamarin.Forms.Controls.Issues
+{
+#if UITEST
+	[Category(UITestCategories.ManualReview)]
+#endif
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.None, 0, "Label with FormattedText, HTML, and Padding shouldn't cause crash", PlatformAffected.iOS)]
+	public class LabelFormattedTextHtmlPadding : TestContentPage
+	{
+		protected override void Init()
+		{
+			var formattedString = new FormattedString();
+			formattedString.Spans.Add(new Span { Text = "This test passes if app doesn't crash. Label is not expected to actually work" });
+
+			Content = new StackLayout()
+			{
+				Margin = 20,
+
+				Children =
+				{
+					new Label()
+					{
+						AutomationId = "LabelFormattedTextHtmlPaddingTest",
+						Text = "If you can see this text, this test has passed"
+					},
+					new Label()
+					{
+						AutomationId = "LabelFormattedTextHtmlPadding",
+						FormattedText = formattedString,
+						TextType = TextType.Html,
+						Padding = 5
+					}
+				}
+			};
+		}
+	}
+}

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems

@@ -1710,6 +1710,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)ShellFlyoutBackground.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)ShellFlyoutContentOffest.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)ShellFlyoutContentWithZeroMargin.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)LabelFormattedTextHtmlPadding.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue13436.xaml.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue13390.cs" />
   </ItemGroup>

Xamarin.Forms.Platform.iOS.UnitTests/HtmlLabelTests.cs

@@ -82,5 +82,30 @@ namespace Xamarin.Forms.Platform.iOS.UnitTests
 
 			Assert.That(actualFont.PointSize, Is.EqualTo(expectedFontSize));
 		}
+
+		[Test, Category("Label"), Category("FormattedText")]
+		[Description("If Label has FormattedText, HTML, and Padding, app should not crash")]
+		public async Task LabelWithFormattedTextHTMLAndPaddingDoesNotCrashApp()
+		{
+			var formattedString = new FormattedString();
+			formattedString.Spans.Add(new Span { Text = "Label with FormattedText, HTML, and Padding" });
+			var label = new Label
+			{
+				FormattedText = formattedString,
+				TextType = TextType.Html,
+				Padding = 5
+			};
+
+			var expected = TextType.Html;
+			var actual = await GetRendererProperty(label, renderer =>
+			{
+				var uiLabel = (UILabel)(renderer as LabelRenderer).Control;
+				uiLabel.Frame = new CoreGraphics.CGRect(0, 0, 200, 200);
+				uiLabel.RecalculateSpanPositions(label);
+				return label.TextType;
+			}, true);
+
+			Assert.That(actual, Is.EqualTo(expected));
+		}
 	}
 }

Xamarin.Forms.Platform.iOS/Extensions/LabelExtensions.cs

@@ -21,6 +21,12 @@ namespace Xamarin.Forms.Platform.MacOS
 	{
 		public static void RecalculateSpanPositions(this NativeLabel control, Label element)
 		{
+			if (element == null)
+				return;
+
+			if (element.TextType == TextType.Html)
+				return;
+
 			if (element?.FormattedText?.Spans == null
 				|| element.FormattedText.Spans.Count == 0)
 				return;