tests/Test-CmClientMissing.ps1

function Test-CmClientMissing {
    [CmdletBinding()]
    param (
        [parameter()][string] $TestName = "Missing Clients",
        [parameter()][string] $TestGroup = "operation",
        [parameter()][string] $Description = "Check for discovered devices without a client",
        [parameter()][hashtable] $ScriptParams
    )
    try {
        $startTime = (Get-Date)
        [System.Collections.Generic.List[PSObject]]$tempdata = @() # for detailed test output to return if needed
        $stat   = "PASS" # do not change this
        $except = "WARNING"
        $msg    = "No issues found" # do not change this either
        $query = "SELECT DISTINCT
fcm.ResourceID,
fcm.Name,
fcm.SiteCode,
fcm.Domain,
sys.Operating_System_Name_and0 as OSName
FROM v_FullCollectionMembership fcm
INNER JOIN v_R_System sys ON fcm.ResourceID = sys.ResourceID
WHERE fcm.IsClient != 1 AND fcm.Name NOT LIKE '%Unknown%' AND fcm.CollectionID = 'SMS00001'
AND sys.Operating_System_Name_and0 IS NOT NULL AND sys.Operating_System_Name_and0 <> ''
ORDER BY fcm.Name"

        $res = Get-CmSqlQueryResult -Query $query -Params $ScriptParams
        if ($res.Count -gt 0) {
            $stat = $except
            $msg  = "$($res.Count) devices are missing a ConfigMgr client"
            $res | Foreach-Object {
                $tempdata.Add(
                    [pscustomobject]@{
                        ComputerName = $($_.Name)
                        ResourceID = $($_.ResourceID)
                        Domain = $($_.Domain)
                        OS = $($_.OSName)
                        SiteCode = $($_.SiteCode)
                    }
                )
            }
        }
    }
    catch {
        $stat = 'ERROR'
        $msg = $_.Exception.Message -join ';'
    }
    finally {
        Write-Output $([pscustomobject]@{
            TestName    = $TestName
            TestGroup   = $TestGroup
            TestData    = $tempdata
            Description = $Description
            Status      = $stat
            Message     = $msg
            RunTime     = $(Get-RunTime -BaseTime $startTime)
            Credential  = $(if($ScriptParams.Credential){$($ScriptParams.Credential).UserName} else { $env:USERNAME })
        })
    }
}