Io abstraction (#7293)

Co-authored-by: p-storm <paul.de.man@gmail.com>

src/modules/imageresizer/tests/ImageResizerUITest.csproj

@@ -69,6 +69,7 @@
     <PackageReference Include="StyleCop.Analyzers" Version="1.1.118">
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>
+    <PackageReference Include="System.IO.Abstractions" Version="12.2.5" />
     <PackageReference Include="System.ValueTuple" Version="4.5.0" />
     <PackageReference Include="xunit" Version="2.4.1" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.3">

src/modules/imageresizer/tests/Models/ResizeBatchTests.cs

@@ -5,7 +5,6 @@
 using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
-using System.Diagnostics;
 using System.IO;
 using System.Linq;
 using System.Threading;

src/modules/imageresizer/tests/Test/AssertEx.cs

@@ -6,7 +6,7 @@ using System;
 using System.Collections.Generic;
 using System.Collections.Specialized;
 using System.ComponentModel;
-using System.IO;
+using System.IO.Abstractions;
 using System.Windows.Media.Imaging;
 using Xunit;
 
@@ -14,6 +14,8 @@ namespace ImageResizer.Test
 {
     internal static class AssertEx
     {
+        private static readonly IFileSystem _fileSystem = new FileSystem();
+
         public static void All<T>(IEnumerable<T> collection, Action<T> action)
         {
             foreach (var item in collection)
@@ -24,7 +26,7 @@ namespace ImageResizer.Test
 
         public static void Image(string path, Action<BitmapDecoder> action)
         {
-            using (var stream = File.OpenRead(path))
+            using (var stream = _fileSystem.File.OpenRead(path))
             {
                 var image = BitmapDecoder.Create(
                     stream,