address some review feedback

test/powershell/Modules/Microsoft.PowerShell.Utility/Set-Date.Tests.ps1

@@ -3,19 +3,8 @@
 # determine whether we're elevated
 Describe "Set-Date" -Tag "CI" {
     BeforeAll {
-        if ( $IsWindows ) {
-            $identity = [System.Security.Principal.WindowsIdentity]::GetCurrent()
-            $windowsPrincipal = new-object 'Security.Principal.WindowsPrincipal' $identity
-            if ($windowsPrincipal.IsInRole("Administrators") -eq 1) { $IsElevated = $true } else { $IsElevated = $false }
-        }
-        else {
-            if ( (whoami) -match "root" ) {
-                $IsElevated = $true
-            }
-            else {
-                $IsElevated = $false
-            }
-        }
+        Import-Module (join-path $psscriptroot "../../Common/Test.Helpers.psm1")
+        $IsElevated = Test-IsElevated
     }
     It "Set-Date should be able to set the date in an elevated context" -Skip:(! $IsElevated) {
         { get-date | set-date } | Should not throw