Simplify Junctions tests, add indirection test

src/libraries/System.IO.FileSystem/tests/Junctions.Windows.cs

@@ -0,0 +1,62 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Collections.Generic;
+using System.Linq;
+using Xunit;
+
+namespace System.IO.Tests
+{
+    [PlatformSpecific(TestPlatforms.Windows)]
+    public class Junctions : BaseSymbolicLinks
+    {
+        protected DirectoryInfo CreateJunction(string junctionPath, string targetPath)
+        {
+            Assert.True(MountHelper.CreateJunction(junctionPath, targetPath));
+            DirectoryInfo junctionInfo = new(junctionPath);
+            return junctionInfo;
+        }
+
+        [Theory]
+        [InlineData(false)]
+        [InlineData(true)]
+        public void Junction_ResolveLinkTarget(bool returnFinalTarget)
+        {
+            string junctionPath = GetRandomLinkPath();
+            string targetPath = GetRandomDirPath();
+
+            Directory.CreateDirectory(targetPath);
+            DirectoryInfo junctionInfo = CreateJunction(junctionPath, targetPath);
+
+            FileSystemInfo? actualTargetInfo = junctionInfo.ResolveLinkTarget(returnFinalTarget);
+            Assert.True(actualTargetInfo is DirectoryInfo);
+            Assert.Equal(targetPath, actualTargetInfo.FullName);
+            Assert.Equal(targetPath, junctionInfo.LinkTarget);
+        }
+
+
+        [Theory]
+        [InlineData(false)]
+        [InlineData(true)]
+        public void Junction_ResolveLinkTarget_WithIndirection(bool returnFinalTarget)
+        {
+            string firstJunctionPath = GetRandomLinkPath();
+            string middleJunctionPath = GetRandomLinkPath();
+            string targetPath = GetRandomDirPath();
+
+            Directory.CreateDirectory(targetPath);
+            _ = CreateJunction(middleJunctionPath, targetPath);
+            DirectoryInfo firstJunctionInfo = CreateJunction(firstJunctionPath, middleJunctionPath);
+
+            string expectedTargetPath = returnFinalTarget ? targetPath : middleJunctionPath;
+
+            FileSystemInfo? actualTargetInfo = firstJunctionInfo.ResolveLinkTarget(returnFinalTarget);
+
+            Assert.True(actualTargetInfo is DirectoryInfo);
+            Assert.Equal(expectedTargetPath, actualTargetInfo.FullName);
+
+            // Always the immediate target
+            Assert.Equal(middleJunctionPath, firstJunctionInfo.LinkTarget);
+        }
+    }
+}

src/libraries/System.IO.FileSystem/tests/System.IO.FileSystem.Tests.csproj

@@ -75,14 +75,12 @@
     <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.Stat.cs" Link="Interop\Unix\System.Native\Interop.Stat.cs" />
   </ItemGroup>
   <ItemGroup Condition="'$(TargetsWindows)' == 'true'">
-    <Compile Include="Base\SymbolicLinks\BaseJunctions.FileSystem.cs" />
     <Compile Include="Base\SymbolicLinks\BaseSymbolicLinks.Windows.cs" />
     <Compile Include="Directory\Delete.Windows.cs" />
-    <Compile Include="Directory\Junctions.cs" />
-    <Compile Include="DirectoryInfo\Junctions.cs" />
     <Compile Include="FileSystemTest.Windows.cs" />
     <Compile Include="FileStream\ctor_options_as.Windows.cs" />
     <Compile Include="FileStream\FileStreamConformanceTests.Windows.cs" />
+    <Compile Include="Junctions.Windows.cs" />
     <Compile Include="RandomAccess\Mixed.Windows.cs" />
     <Compile Include="RandomAccess\NoBuffering.Windows.cs" />
     <Compile Include="RandomAccess\SectorAlignedMemory.Windows.cs" />