Enable creating relative symlinks on Windows with New-Item (#8783)

src/System.Management.Automation/engine/SessionStateContainer.cs

@@ -3535,7 +3535,12 @@ namespace System.Management.Automation
                             throw PSTraceSource.NewInvalidOperationException(SessionStateStrings.PathNotFound, targetPath);
                         }
 
-                        content = globbedTarget[0];
+                        // If the original target was a relative path, we want to leave it as relative if it did not require
+                        // globbing to resolve.
+                        if (WildcardPattern.ContainsWildcardCharacters(targetPath))
+                        {
+                            content = globbedTarget[0];
+                        }
                     }
 
                     NewItemPrivate(providerInstance, composedPath, type, content, context);

test/powershell/Modules/Microsoft.PowerShell.Management/FileSystem.Tests.ps1

@@ -500,7 +500,6 @@ Describe "Hard link and symbolic link tests" -Tags "CI", "RequireAdminOnWindows"
 
     Context "Get-ChildItem and symbolic links" {
         BeforeAll {
-            $TestDrive = "TestDrive:"
             $alphaDir = Join-Path $TestDrive "sub-alpha"
             $alphaLink = Join-Path $TestDrive "link-alpha"
             $alphaFile1 = Join-Path $alphaDir "AlphaFile1.txt"
@@ -671,7 +670,6 @@ Describe "Copy-Item can avoid copying an item onto itself" -Tags "CI", "RequireA
         # attempt is made to copy an item onto itself.
         $selfCopyKey = "SelfCopy"
 
-        $TestDrive = "TestDrive:"
         $subDir = "$TestDrive/sub"
         $otherSubDir = "$TestDrive/other-sub"
         $fileName = "file.txt"

test/powershell/Modules/Microsoft.PowerShell.Management/New-Item.Tests.ps1

@@ -254,6 +254,18 @@ Describe "New-Item with links" -Tags @('CI', 'RequireAdminOnWindows') {
         $symbolicLinkPath = New-Item -ItemType SymbolicLink -Path "$tmpDirectory/$folderName/" -Value "/bar/"
         $symbolicLinkPath | Should -Not -BeNullOrEmpty
     }
+
+    It "New-Item -ItemType SymbolicLink should be able to create a relative link" -Skip:(!$IsWindows) {
+        try {
+            Push-Location $TestDrive
+            $relativeFilePath = Join-Path -Path . -ChildPath "relativefile.txt"
+            $file = New-Item -ItemType File -Path $relativeFilePath
+            $link = New-Item -ItemType SymbolicLink -Path ./link -Target $relativeFilePath
+            $link.Target | Should -BeExactly $relativeFilePath
+        } finally {
+            Pop-Location
+        }
+    }
 }
 
 Describe "New-Item with links fails for non elevated user if developer mode not enabled on Windows." -Tags "CI" {