Can I pass a function and call it in a PSJobs scriptblock, and receive a return value?

Question

When I run get-job | receive-job -keep I get no results and have no way to verify that my function is passed and working. Can I pass a function like this into a psjob? How do I capture the return value afterwards?

$servers = @("xxxx", "xxxx")
$jobs = New-Object System.Collections.ArrayList;
foreach ($server in $servers)
{
    $jobName = $server + "_job";
    $scriptBlock = 
    {
    
        param($server)
        param($portNumber)
        
        Function testPort ($server, $portNumber)
        {
            $testPort = New-Object System.Net.Sockets.TCPClient # -ArgumentList $server, 3389;
            $testPort.SendTimeout = 3;
            try
            {
                $testPort.Connect($server, 3389);
            }
            catch
            {
                #do nothing;
            }
            $result = $testPort.Connected;
            $testPort.Close();
                    
            return $result;
        }
    
        testPort -server $server -portNumber 3389; sleep 10;    
    }
    $portNumber = "3389";
    
    #Start-Job -Name $jobName -ScriptBlock {$scriptBlock} -ArgumentList $server, $portNumber;

    $jobs.Add((Start-Job -Name $jobName -ScriptBlock {$scriptBlock} -ArgumentList $server, $portNumber | Out-Null));

}

$jobsReturnValues = New-Object System.Collections.ArrayList;
foreach ($job in $jobs)
{
    $jobsReturnValues.Add(($job | Wait-Job | Receive-Job | Out-Null));
}

Answer 1

The code is almost fine, you did not have many errors. The main issue was the use of Out-Null, the { } on -ScriptBlock {$scriptBlock} and the param( ) block was defined 2 times in your function. I did a little modification to your function too :)

$servers = @('google.com','twitter.com')
$jobs = New-Object System.Collections.ArrayList;
$testPort = 80

foreach ($server in $servers)
{
    $jobName = $server + "_job";
    $scriptBlock = {
        param(
            [string]$server,
            [int]$portNumber
        )
        
        Function testPort ($server, $portNumber)
        {
            $testPort = New-Object System.Net.Sockets.TCPClient # -ArgumentList $server, 3389;
            $testPort.SendTimeout = 3;
            try
            {
                $testPort.Connect($server, $portNumber);
            }
            catch
            {
                #do nothing;
            }
            
            $result = $testPort.Connected;
            $testPort.Close();
                    
            [pscustomobject]@{
                ServerName = $server
                Port = $portNumber
                TestConnection = $result
            }
        }

        testPort -server $server -portNumber $portNumber
    }

    $jobs.Add((Start-Job -Name $jobName -ScriptBlock $scriptBlock -ArgumentList $server, $testPort)) > $null;

}

$jobsReturnValues = New-Object System.Collections.ArrayList;
foreach ($job in $jobs)
{
    $jobsReturnValues.Add(($job | Receive-Job -Wait -AutoRemoveJob)) > $null;
}

Looks like this:

PS C:\> $jobsReturnValues|select * -ExcludeProperty RunspaceID|ft

ServerName  Port TestConnection
----------  ---- --------------
google.com    80           True
twitter.com   80           True