Test-ClassResource.ps1

function Test-ClassResource
{
    param(
        [Parameter(ValueFromPipeline=$True,Mandatory=$True)]
        [string]$fileName
    )
    $ast = [System.Management.Automation.Language.Parser]::ParseFile($fileName, [ref]$null, [ref]$null)

    $result = foreach ($item in $ast.FindAll({$args[0] -is [System.Management.Automation.Language.AttributeAst]}, $false))
    {
        if ($item.Extent.Text -eq '[DscResource()]')
        {
            $true
        }
    }
    if ($result)
    {
        $true
    }
    else
    {
        $false
    }
}