pester_ssl_expiry_validation.ps1

$script:_https_certs = @{}


function Add-HTTPSCertificateCheck {
  param(
    [string]$Url,
    [TimeSpan]$ValidityTime
  )
  if ($script:_https_certs.Keys -contains $Url) {
    throw "url '$Url' already added!"
  }
  $_https_certs[$Url] = @{
    Url          = $Url
    ValidityTime = $ValidityTime
  }
}

Add-HTTPSCertificateCheck -Url "https://somesite:433" -ValidityTime $(New-TimeSpan -Days 30)

describe "sslchecks" {

  foreach ($c in $script:_https_certs.Keys) {
    it "check $c" {
      $o = $_https_certs[$c]
      $req = [Net.HttpWebRequest]::Create($o.Url)
      $resp = $req.GetResponse()
      $resp | Should -Not -BeNullOrEmpty

      [datetime]$expiration = [System.DateTime]::Parse($req.ServicePoint.Certificate.GetExpirationDateString())
      $remainingTime = $expiration - (Get-Date)
      $remainingTime | Should -BeGreaterThan $o.ValidityTime
    }
  }
    
}