Adding a filter to It via wrapper

ItWithTag.ps1

function ItWithTag (
    $Name, 
    $Body, 
    $Tag
) {
    if ($null -eq $global:Tags -or 0 -eq $global:Tags.Length -or $global:Tags -contains $Tag) { 
        It $Name $Body
    }
}

$global:tags = @("t")

Describe "a" {
    Write-Host d1
    ItWithTag "does not run" { 
        Write-Host t1
    }

    ItWithTag "runs" -Tag "t" { 
        Write-Host t2
    }
}