Merge pull request #144 from unoplatform/dev/jela/doc-update

Update `Link` support docs

Author: jeromelaban

doc/using-xamlmerge.md

@@ -65,9 +65,9 @@ To limit the impact of the traversal, this task takes all resource dictionaries
 1. By default, the generated file is called `Generated\mergedpages.xaml`, but can be overridden as follows:
 
     ```xml
-    <PropertyGroup>
-      <XamlMergeOutputFile>Themes\Generic.xaml</XamlMergeOutputFile>
-    </PropertyGroup>
+    <ItemGroup>
+      <XamlMergeOutputFiles Include="Themes\Generic.xaml" />
+    </ItemGroup>
     ```
 
 1. The generated file can be referenced as follows:
@@ -86,6 +86,18 @@ To limit the impact of the traversal, this task takes all resource dictionaries
 
     Then replace `REPLACE_ME/` with either the library name if you're adding the package to a class library, or with nothing if you're adding it to your main project (e.g. `ms-appx:///Generated/mergedpages.xaml`).
 
+1. If your project is multi-targeted and that your set of input files is different for each target, the output file for each target must be placed in the intermediate output to avoid breaking the incremental compilation:
+
+    ```xml
+    <ItemGroup>
+      <XamlMergeOutputFiles
+        Include="$(IntermediateOutputPath)\Themes\Generic.xaml"
+        Link="Themes\Generic.xaml" />
+    </ItemGroup>
+    ```
+
+    The `Link` value is the path that can be used in the `ResourceDictionary.Source` property.
+
 ## Multiple generated files
 
 There are scenarios where placing groups of XAML files in separate merged files are useful, particularly, when IL Linking must be used.

src/Uno.XamlMerge.Tests/Given_BatchMergeXaml.cs

@@ -47,6 +47,22 @@ public void When_HR_Enabled_Main_App()
         ValidateOutput(task);
     }
 
+    [TestMethod]
+    public void When_HR_Enabled_Main_App_No_Overwrite()
+    {
+        var task = CreateMerger(isHotReloadEnabled: true, isMainAssembly: true);
+
+        Assert.IsTrue(task.Execute());
+
+        var originalFiles = task.MergedXamlFiles.Select(f => new FileInfo(f.ItemSpec).LastWriteTimeUtc).ToArray();
+
+        Assert.IsTrue(task.Execute());
+
+        var newFiles = task.MergedXamlFiles.Select(f => new FileInfo(f.ItemSpec).LastWriteTimeUtc).ToArray();
+
+        Assert.IsTrue(originalFiles.SequenceEqual(newFiles));
+    }
+
     [TestMethod]
     public void When_Key_TargeType_Conflict()
     {
@@ -107,7 +123,6 @@ public void When_Duplicate_ThemeResources_With_Prefix()
         ValidateOutput(task);
     }
 
-
     [TestMethod]
     public void When_Duplicate_ThemeResources_With_Ignored_Prefix()
     {

src/Uno.XamlMerge.Tests/Scenarios/When_HR_Enabled_Main_App_No_Overwrite/Input_Dictionary_1.xml

@@ -0,0 +1,7 @@
+<ResourceDictionary
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+	xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006">
+
+    <x:String x:Key="Key1">Value1</x:String>
+</ResourceDictionary>

src/Uno.XamlMerge.Tests/Scenarios/When_HR_Enabled_Main_App_No_Overwrite/Input_Dictionary_2.xml

@@ -0,0 +1,7 @@
+<ResourceDictionary
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+	xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006">
+
+    <x:String x:Key="Key2">Value2</x:String>
+</ResourceDictionary>

src/Uno.XamlMerge.Tests/Scenarios/When_HR_Enabled_Main_App_No_Overwrite/expected.xml

@@ -0,0 +1,11 @@
+<!-- Generating a resource dictionary that references existing dictionaries for HotReload support -->
+<!-- Proper merging of XAML files will happen if you build in Release configuration -->
+<ResourceDictionary
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006">
+    <ResourceDictionary.MergedDictionaries>
+        <ResourceDictionary Source="ms-appx:///TestAssemblyName/When_HR_Enabled/Input_Dictionary_1.xml" />
+        <ResourceDictionary Source="ms-appx:///TestAssemblyName/When_HR_Enabled/Input_Dictionary_2.xml" />
+    </ResourceDictionary.MergedDictionaries>
+</ResourceDictionary>