Addressed code review comments.

Author: Brian McBrayer

Directory.Build.props

@@ -13,6 +13,7 @@
     <DefineConstants Condition="'$(TargetFramework)' != 'net461'">$(DefineConstants);FEATURE_FILE_SYSTEM_ACL_EXTENSIONS</DefineConstants>
     <DefineConstants Condition="'$(TargetFramework)' == 'net6.0' OR '$(TargetFramework)' == 'net5.0' OR '$(TargetFramework)' == 'netcoreapp3.1' OR '$(TargetFramework)' == 'netstandard2.1'">$(DefineConstants);FEATURE_ASYNC_FILE;FEATURE_ENUMERATION_OPTIONS;FEATURE_ADVANCED_PATH_OPERATIONS;FEATURE_PATH_JOIN_WITH_SPAN</DefineConstants>
     <DefineConstants Condition="'$(TargetFramework)' == 'net6.0' OR '$(TargetFramework)' == 'net5.0'">$(DefineConstants);FEATURE_FILE_MOVE_WITH_OVERWRITE;FEATURE_SUPPORTED_OS_ATTRIBUTE;FEATURE_FILE_SYSTEM_WATCHER_FILTERS;FEATURE_ENDS_IN_DIRECTORY_SEPARATOR;FEATURE_PATH_JOIN_WITH_PARAMS;FEATURE_PATH_JOIN_WITH_FOUR_PATHS</DefineConstants>
+	<DefineConstants Condition="'$(TargetFramework)' == 'net6.0'">$(DefineConstants);FEATURE_FILE_SYSTEM_INFO_LINK_TARGET</DefineConstants>
   </PropertyGroup>
   <ItemGroup>
     <PackageReference Include="Nerdbank.GitVersioning" Version="3.4.255">

src/System.IO.Abstractions.TestingHelpers/MockDirectoryInfo.cs

@@ -131,11 +131,11 @@ public override DateTime LastWriteTimeUtc
             set { GetMockFileDataForWrite().LastWriteTime = value.ToLocalTime(); }
         }
 
-#if NET6_0_OR_GREATER
+#if FEATURE_FILE_SYSTEM_INFO_LINK_TARGET
         /// <inheritdoc />
         public override string LinkTarget
         {
-            get { return null; }
+            get { return GetMockFileDataForRead().LinkTarget; }
         }
 #endif
 

src/System.IO.Abstractions.TestingHelpers/MockFileData.cs

@@ -101,6 +101,9 @@ public MockFileData(MockFileData template)
             CreationTime = template.CreationTime;
             LastAccessTime = template.LastAccessTime;
             LastWriteTime = template.LastWriteTime;
+#if FEATURE_FILE_SYSTEM_INFO_LINK_TARGET
+            LinkTarget = template.LinkTarget;
+#endif
         }
 
         /// <summary>
@@ -135,6 +138,13 @@ public string TextContents
         /// </summary>
         public DateTimeOffset LastWriteTime { get; set; } = new DateTimeOffset(2010, 01, 04, 00, 00, 00, TimeSpan.FromHours(4));
 
+#if FEATURE_FILE_SYSTEM_INFO_LINK_TARGET
+        /// <summary>
+        /// Gets or sets the link target of the <see cref="MockFileData"/>.
+        /// </summary>
+        public string LinkTarget { get; set; } = null;
+#endif
+
         /// <summary>
         /// Casts a string into <see cref="MockFileData"/>.
         /// </summary>

src/System.IO.Abstractions.TestingHelpers/MockFileInfo.cs

@@ -178,11 +178,16 @@ public override DateTime LastWriteTimeUtc
             }
         }
 
-#if NET6_0_OR_GREATER
+#if FEATURE_FILE_SYSTEM_INFO_LINK_TARGET
         /// <inheritdoc />
         public override string LinkTarget
         {
-            get { return null; }
+            get
+            {
+                // TODO Refactor to match #791 style (also hold on merge until that is merged)
+                if (MockFileData == null) throw CommonExceptions.FileNotFound(path);
+                return MockFileData.LinkTarget;
+            }
         }
 #endif
 

src/System.IO.Abstractions/DirectoryInfoWrapper.cs

@@ -96,7 +96,7 @@ public override DateTime LastWriteTimeUtc
             set { instance.LastWriteTimeUtc = value; }
         }
 
-#if NET6_0_OR_GREATER
+#if FEATURE_FILE_SYSTEM_INFO_LINK_TARGET
         /// <inheritdoc />
         public override string LinkTarget
         {

src/System.IO.Abstractions/FileInfoWrapper.cs

@@ -94,7 +94,7 @@ public override DateTime LastWriteTimeUtc
             set { instance.LastWriteTimeUtc = value; }
         }
 
-#if NET6_0_OR_GREATER
+#if FEATURE_FILE_SYSTEM_INFO_LINK_TARGET
         /// <inheritdoc />
         public override string LinkTarget
         {

src/System.IO.Abstractions/FileSystemInfoBase.cs

@@ -54,7 +54,7 @@ internal FileSystemInfoBase() { }
         /// <inheritdoc cref="FileSystemInfo.LastWriteTimeUtc"/>
         public abstract DateTime LastWriteTimeUtc { get; set; }
 
-#if NET6_0_OR_GREATER
+#if FEATURE_FILE_SYSTEM_INFO_LINK_TARGET
         /// <inheritdoc cref="FileSystemInfo.LinkTarget"/>
         public abstract string LinkTarget { get; }
 #endif