[Xaml[C]] Do not instantiate DataTemplate Content at parsing time (#683)

* [Xaml] rename VisitChildrenFirst

* [Xaml] rework SkipChildren in XamlNode

* [Xaml] fix 45179

* fix

5 files changed, 101 insertions, 0 deletions

diff --git a/Xamarin.Forms.Xaml.UnitTests/Issues/Bz27863.xaml.cs b/Xamarin.Forms.Xaml.UnitTests/Issues/Bz27863.xaml.cs
index 03ebaaf9..1120a033 100644
--- a/Xamarin.Forms.Xaml.UnitTests/Issues/Bz27863.xaml.cs
+++ b/Xamarin.Forms.Xaml.UnitTests/Issues/Bz27863.xaml.cs
@@ -4,6 +4,7 @@ using System.Collections.Generic;
 using Xamarin.Forms;
 
 using NUnit.Framework;
+using Xamarin.Forms.Core.UnitTests;
 
 namespace Xamarin.Forms.Xaml.UnitTests
 {
@@ -22,6 +23,18 @@ namespace Xamarin.Forms.Xaml.UnitTests
 		[TestFixture]
 		class Tests
 		{
+			[SetUp]
+			public void Setup()
+			{
+				Device.PlatformServices = new MockPlatformServices();
+			}
+
+			[TearDown]
+			public void TearDown()
+			{
+				Device.PlatformServices = null;
+			}
+
 			[TestCase(true)]
 			[TestCase(false)]
 			public void DataTemplateInResourceDictionaries (bool useCompiledXaml)
diff --git a/Xamarin.Forms.Xaml.UnitTests/Issues/Bz27968.xaml.cs b/Xamarin.Forms.Xaml.UnitTests/Issues/Bz27968.xaml.cs
index 2482e9f0..507073d7 100644
--- a/Xamarin.Forms.Xaml.UnitTests/Issues/Bz27968.xaml.cs
+++ b/Xamarin.Forms.Xaml.UnitTests/Issues/Bz27968.xaml.cs
@@ -4,6 +4,7 @@ using System.Collections.Generic;
 using Xamarin.Forms;
 
 using NUnit.Framework;
+using Xamarin.Forms.Core.UnitTests;
 
 namespace Xamarin.Forms.Xaml.UnitTests
 {
@@ -26,6 +27,18 @@ namespace Xamarin.Forms.Xaml.UnitTests
 		[TestFixture]
 		class Tests
 		{
+			[SetUp]
+			public void Setup()
+			{
+				Device.PlatformServices = new MockPlatformServices();
+			}
+
+			[TearDown]
+			public void TearDown()
+			{
+				Device.PlatformServices = null;
+			}
+
 			[TestCase(true)]
 			[TestCase(false)]
 			public void BaseClassIdentifiersAreValidForResources (bool useCompiledXaml)
diff --git a/Xamarin.Forms.Xaml.UnitTests/Issues/Bz45179.xaml b/Xamarin.Forms.Xaml.UnitTests/Issues/Bz45179.xaml
new file mode 100644
index 00000000..a89aa295
--- /dev/null
+++ b/Xamarin.Forms.Xaml.UnitTests/Issues/Bz45179.xaml
@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ContentPage 
+	xmlns="http://xamarin.com/schemas/2014/forms"
+	xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+	xmlns:local="clr-namespace:Xamarin.Forms.Xaml.UnitTests"
+	x:Class="Xamarin.Forms.Xaml.UnitTests.Bz45179">
+	<ContentPage.Resources>
+		<ResourceDictionary>
+			<DataTemplate x:Key="dt0">
+				<local:Bz45179_0/>
+			</DataTemplate>
+		</ResourceDictionary>
+	</ContentPage.Resources>
+</ContentPage>
\ No newline at end of file
diff --git a/Xamarin.Forms.Xaml.UnitTests/Issues/Bz45179.xaml.cs b/Xamarin.Forms.Xaml.UnitTests/Issues/Bz45179.xaml.cs
new file mode 100644
index 00000000..1dbdb44d
--- /dev/null
+++ b/Xamarin.Forms.Xaml.UnitTests/Issues/Bz45179.xaml.cs
@@ -0,0 +1,55 @@
+using System;
+using System.Collections.Generic;
+using NUnit.Framework;
+using Xamarin.Forms;
+using Xamarin.Forms.Core.UnitTests;
+
+namespace Xamarin.Forms.Xaml.UnitTests
+{
+	public class Bz45179_0 : ContentView {
+		public static int creator_count;
+		public Bz45179_0()
+		{
+			creator_count++;
+		}
+
+	}
+	public partial class Bz45179 : ContentPage
+	{
+		public Bz45179()
+		{
+			InitializeComponent();
+		}
+
+		public Bz45179(bool useCompiledXaml)
+		{
+			//this stub will be replaced at compile time
+		}
+
+		[TestFixture]
+		class Tests
+		{
+			[SetUp]
+			public void Setup()
+			{
+				Device.PlatformServices = new MockPlatformServices();
+			}
+
+			[TearDown]
+			public void TearDown()
+			{
+				Device.PlatformServices = null;
+			}
+
+			[TestCase(true)]
+			[TestCase(false)]
+			public void DTDoNotInstantiateTheirContent(bool useCompiledXaml)
+			{
+				Bz45179_0.creator_count = 0;
+				Assume.That(Bz45179_0.creator_count, Is.EqualTo(0));
+				var page = new Bz45179(useCompiledXaml);
+				Assert.That(Bz45179_0.creator_count, Is.EqualTo(0));
+			}
+		}
+	}
+}
\ No newline at end of file
diff --git a/Xamarin.Forms.Xaml.UnitTests/Xamarin.Forms.Xaml.UnitTests.csproj b/Xamarin.Forms.Xaml.UnitTests/Xamarin.Forms.Xaml.UnitTests.csproj
index b66a0824..ae250cd1 100644
--- a/Xamarin.Forms.Xaml.UnitTests/Xamarin.Forms.Xaml.UnitTests.csproj
+++ b/Xamarin.Forms.Xaml.UnitTests/Xamarin.Forms.Xaml.UnitTests.csproj
@@ -406,6 +406,9 @@
     <Compile Include="Issues\Unreported008.xaml.cs">
       <DependentUpon>Unreported008.xaml</DependentUpon>
     </Compile>
+    <Compile Include="Issues\Bz45179.xaml.cs">
+      <DependentUpon>Bz45179.xaml</DependentUpon>
+    </Compile>
   </ItemGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
   <Import Project="..\.nuspec\Xamarin.Forms.Debug.targets" />
@@ -733,6 +736,9 @@
     <EmbeddedResource Include="Issues\Unreported008.xaml">
       <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
     </EmbeddedResource>
+    <EmbeddedResource Include="Issues\Bz45179.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
   </ItemGroup>
   <ItemGroup>
     <Service Include="{82A7F48D-3B50-4B1E-B82E-3ADA8210C358}" />