pester-example.ps1

function Join-PathElement {
    param(
        [string[]]$Element
    )

    [array]$FullPath = $Element[0]
    for ($i = 1; $i -lt $Element.Count; $i++) {
        $FullPath += Join-Path -Path $FullPath -ChildPath $Element[$i]
    }
    $Id = $FullPath.Count - 1
    Write-Output ($FullPath[$Id])
}

Describe 'Przyklad testu' {
  It 'Sprawdzanie wyniku' {
     Join-PathElement -Element 'C:\Users', 'Temp', 'file.txt' | Should -Be 'C:\Users\Temp\file.txt'
  }
}