Public/Network/Test-IsValidIPv6.ps1

function Test-IsValidIPv6 {
  <#
.SYNOPSIS
    Verifies if passed parameter is a valid IP v6 address
.DESCRIPTION
    Verifies if passed parameter is a valid IP v6 address. Can take single string or array of strings. Can also accept input from the pipeline.
.EXAMPLE
    Test-IsValidIPv6 '::1'
 
    Would return
    True
.EXAMPLE
    Test-IsValidIPv6 -IPAddress '::1' -Verbose
 
    Would return
    VERBOSE: Starting Test-IsValidIPv6
    VERBOSE: The string being tested if a valid IPv6 address is [::1]
    True
    VERBOSE: Ending Test-IsValidIPv6
.EXAMPLE
    '::1','invalid' | Test-IsValidIPv6 -IncludeInput
 
    Input Result
    ----- ------
    ::1 True
    invalid False
#>


  #region Param
  [CmdletBinding(ConfirmImpact = 'None')]
  [Outputtype('bool')]
  Param (
    [parameter(ValueFromPipeLine, ValueFromPipeLineByPropertyName)]
    [Alias('IP')]
    [string[]] $IPAddress,

    [switch] $IncludeInput
  )
  #endregion Param

  begin {
    Write-Invocation $MyInvocation
  }

  process {
    foreach ($i in $IPAddress) {
      try {
        Out-Verbose "The string being tested if a valid IPv6 address is [$i]"
        $check = [ipaddress] $i
        # added check below to cover issue if enter only 3 octets
        # [ipaddress] "10.1.4" resolves to "10.1.0.4"
        if (($i -eq $check) -and ($check.AddressFamily -eq 'InterNetworkV6')) {
          if ($IncludeInput) {
            New-Object -TypeName psobject -Property ([ordered] @{Input = $i; Result = $true })
          } else {
            Write-Output -InputObject $true
          }
        } else {
          if ($IncludeInput) {
            New-Object -TypeName psobject -Property ([ordered] @{Input = $i; Result = $false })
          } else {
            Write-Output -InputObject $false
          }
        }
      } catch {
        if ($IncludeInput) {
          New-Object -TypeName psobject -Property ([ordered] @{Input = $i; Result = $false })
        } else {
          Write-Output -InputObject $false
        }
      }
    }
  }

  end {
    Out-Verbose $fxn "Complete."
  }
}