# Example for folders and files :
$folder = 'c:\windows'
$file = 'notepad.exe'
test-path -Path $folder
test-path -Path "$dossier\$fichier"

$folder2 = 'c:\windows2'
$file2 = 'notepad2.exe'
test-path -Path $dossier2
test-path -Path "$dossier\$fichier2"

# For the registry :
Test-Path -Path HKLM:\Software\Microsoft
Test-Path -Path HKLM:\Software\Microsoft2

# For Active Directory:
$dc = (Get-ADDomain).distinguishedname
$ou = 'demo_computers'
import-module -Name ActiveDirectory
test-path -Path "ad:ou=$ou,$dc"