Added the unit test project

Author: 0x5bfa

Directory.Packages.props

@@ -59,5 +59,6 @@
     <PackageVersion Include="MSTest.TestAdapter" Version="3.8.3" />
     <PackageVersion Include="MSTest.TestFramework" Version="3.8.3" />
     <PackageVersion Include="Dongle.GuidRVAGen" Version="1.0.5" />
+    <PackageVersion Include="Microsoft.TestPlatform.TestHost" Version="17.13.0" />
   </ItemGroup>
 </Project>

Files.slnx

@@ -9,7 +9,7 @@
     <File Path="Directory.Packages.props" />
   </Folder>
   <Folder Name="/src/" />
-  <Folder Name="/src/core/" Id="8d626ea8-cb54-bc41-363a-217881beba6e">
+  <Folder Name="/src/core/">
     <Project Path="src/Files.Core.SourceGenerator/Files.Core.SourceGenerator.csproj" />
     <Project Path="src/Files.Core.Storage/Files.Core.Storage.csproj">
       <Platform Solution="*|arm64" Project="arm64" />
@@ -22,7 +22,7 @@
       <Platform Solution="*|x86" Project="x86" />
     </Project>
   </Folder>
-  <Folder Name="/src/platforms/" Id="82099983-647e-f067-e69a-cd800643a918">
+  <Folder Name="/src/platforms/">
     <Project Path="src/Files.App (Package)/Files.Package.wapproj" Type="c7167f0d-bc9f-4e6e-afe1-012c56b48db5">
       <Deploy />
     </Project>
@@ -81,6 +81,12 @@
       <Platform Solution="*|x86" Project="x86" />
       <Deploy />
     </Project>
+    <Project Path="tests/Files.App.UnitTests/Files.App.UnitTests.csproj">
+      <Platform Solution="*|arm64" Project="ARM64" />
+      <Platform Solution="*|x64" Project="x64" />
+      <Platform Solution="*|x86" Project="x86" />
+      <Deploy />
+    </Project>
     <Project Path="tests/Files.InteractionTests/Files.InteractionTests.csproj">
       <Platform Solution="*|arm64" Project="arm64" />
       <Platform Solution="*|x64" Project="x64" />

tests/Files.App.UnitTests/App.xaml

@@ -0,0 +1,15 @@
+<Application
+	x:Class="Files.App.UnitTests.App"
+	xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+	xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+	xmlns:local="using:Files.App.UnitTests">
+
+	<Application.Resources>
+		<ResourceDictionary>
+			<ResourceDictionary.MergedDictionaries>
+				<XamlControlsResources xmlns="using:Microsoft.UI.Xaml.Controls" />
+			</ResourceDictionary.MergedDictionaries>
+		</ResourceDictionary>
+	</Application.Resources>
+
+</Application>

tests/Files.App.UnitTests/App.xaml.cs

@@ -0,0 +1,30 @@
+// Copyright (c) Files Community
+// Licensed under the MIT License.
+
+using Microsoft.UI.Xaml;
+using Microsoft.VisualStudio.TestTools.UnitTesting.AppContainer;
+
+namespace Files.App.UnitTests
+{
+	public partial class App : Application
+	{
+		private Window? _window;
+
+		public App()
+		{
+			InitializeComponent();
+		}
+
+		protected override void OnLaunched(LaunchActivatedEventArgs args)
+		{
+			Microsoft.VisualStudio.TestPlatform.TestExecutor.UnitTestClient.CreateDefaultUI();
+
+			_window = new MainWindow();
+			_window.Activate();
+
+			UITestMethodAttribute.DispatcherQueue = _window.DispatcherQueue;
+
+			Microsoft.VisualStudio.TestPlatform.TestExecutor.UnitTestClient.Run(System.Environment.CommandLine);
+		}
+	}
+}