Private/TestIsValidAttribute.ps1

function TestIsValidAdAttribute {
    [OutputType([bool])]
    [CmdletBinding()]
    param
    (
        [Parameter(Mandatory)]
        [ValidateNotNullOrEmpty()]
        [string]$Name
    )

    if ($Name -in (Get-AvailableAdUserAttribute).ValidName) {
        $true
    } else {
        $false
    }
}