[Xaml] allow the Previewer to provide their own Xaml files for any type (#262)

* [Xaml] allow the Previewer to provide their own Xaml files for any type

* [Xaml] use a Func instead of an interface, easier to use by reflection. Add tests

* [XamlC] move the InitializeComponent duplication to XamlC task

* [XamlC] generate branching code

* [XamlC] fix the XamlC issue

* [XamlC] make the API public

* [docs] fix docs

1 files changed, 55 insertions, 0 deletions

diff --git a/Xamarin.Forms.Xaml.UnitTests/XamlLoaderGetXamlForTypeTests.xaml.cs b/Xamarin.Forms.Xaml.UnitTests/XamlLoaderGetXamlForTypeTests.xaml.cs
new file mode 100644
index 00000000..10c3f2e2
--- /dev/null
+++ b/Xamarin.Forms.Xaml.UnitTests/XamlLoaderGetXamlForTypeTests.xaml.cs
@@ -0,0 +1,55 @@
+using System;
+using System.Collections.Generic;
+
+using NUnit.Framework;
+
+using Xamarin.Forms;
+
+namespace Xamarin.Forms.Xaml.UnitTests
+{
+	public partial class XamlLoaderGetXamlForTypeTests : ContentPage
+	{
+		public XamlLoaderGetXamlForTypeTests()
+		{
+			InitializeComponent();
+		}
+
+		public XamlLoaderGetXamlForTypeTests(bool useCompiledXaml)
+		{
+			//this stub will be replaced at compile time
+		}
+
+		[TestFixture]
+		public class Tests
+		{
+			[SetUp]
+			public void SetUp()
+			{
+				Xamarin.Forms.Xaml.Internals.XamlLoader.XamlFileProvider = null;
+			}
+
+			[TestCase(false)]
+			[TestCase(true)]
+			public void XamlContentIsReplaced(bool useCompiledXaml)
+			{
+				var layout = new XamlLoaderGetXamlForTypeTests(useCompiledXaml);
+				Assert.That(layout.Content, Is.TypeOf<Button>());
+
+				Xamarin.Forms.Xaml.Internals.XamlLoader.XamlFileProvider = (t) => {
+					if (t == typeof(XamlLoaderGetXamlForTypeTests))
+						return @"
+	<ContentPage xmlns=""http://xamarin.com/schemas/2014/forms""
+		xmlns:x=""http://schemas.microsoft.com/winfx/2009/xaml""
+		x:Class=""Xamarin.Forms.Xaml.UnitTests.XamlLoaderGetXamlForTypeTests"">
+		<Label x:Name=""Label""/>
+	</ContentPage>";
+					return null;
+				};
+
+				layout = new XamlLoaderGetXamlForTypeTests(useCompiledXaml);
+				Assert.That(layout.Content, Is.TypeOf<Label>());
+			}
+		}
+	}
+}
+