Loop is duplicating output - arrays

Question

The below code is designed to check two hard-coded service names (these will never change) and if they are not found to then state the services are not present. It does this but it outputs two lines as there are two services to check.
Is there a way to alter this so that only one output is given after checking both services?
$servicenames = ("Service 1", "Service 2")
Write-Host 'Checking for Services'
function servicevalidation {
foreach ($sn in $servicenames) {
if ((Get-Service "$servicenames*" -Include $servicenames) -eq $null) {
Write-Host 'Young jedi you are mistaken, this server is not a collector!'
} else {
Write-Host "$servicenames present"
}
}
}

Answer 1

Get-Service accepts a list of services, so you can simply do the following without a loop. I would recommend passing the services as an argument, though, if you're encapsulating the check in a function anyway.
function servicevalidation($svc) {
if (Get-Service $svc -ErrorAction SilentlyContinue) {
Write-Host 'Young jedi you are mistaken, this server is not a collector!'
} else {
Write-Host "$svc present."
}
}
servicevalidation $servicenames
The -ErrorAction SilentlyContinue suppresses error output in case a service is not present.
If you want to know which service exactly is missing you could do so with a Where-Object filter:
function servicevalidation($svc) {
$missing = $svc | Where-Object {
-not (Get-Service $_ -ErrorAction SilentlyContinue)
}
if ($missing) {
Write-Host "missing service: $missing"
} else {
Write-Host "$svc present."
}
}