Add test to verify filesystem provider isn't used when accessing root path in psdrive (#7173)

* add test to verify filesystem isn't used when not in filesystem drive

test/powershell/Modules/Microsoft.PowerShell.Management/Set-Location.Tests.ps1

@@ -54,6 +54,22 @@ Describe "Set-Location" -Tags "CI" {
         $(Get-Location).Path | Should -BeExactly $testPath.FullName
     }
 
+    It "Should not use filesystem root folder if not in filesystem provider" -Skip:(!$IsWindows) {
+        # find filesystem root folder that doesn't exist in HKCU:
+        $foundFolder = $false
+        foreach ($folder in Get-ChildItem "${env:SystemDrive}\" -Directory) {
+            if (-Not (Test-Path "HKCU:\$($folder.Name)")) {
+                $testFolder = $folder.Name
+                $foundFolder = $true
+                break
+            }
+        }
+        $foundFolder | Should -BeTrue
+        Set-Location HKCU:\
+        { Set-Location ([System.IO.Path]::DirectorySeparatorChar + $testFolder) -ErrorAction Stop } |
+            Should -Throw -ErrorId "PathNotFound,Microsoft.PowerShell.Commands.SetLocationCommand"
+    }
+
     Context 'Set-Location with no arguments' {
 
         It 'Should go to $env:HOME when Set-Location run with no arguments from FileSystem provider' {