Powershell CompleteInput example

completion.ps1

$cmd = "ConvertTo-Json -"
$ret = [System.Management.Automation.CommandCompletion]::MapStringInputToParsedInput($cmd, $cmd.Length)

$candidates = [System.Management.Automation.CommandCompletion]::CompleteInput(
    $ret.Item1,
    $ret.Item2,
    $ret.Item3,
    $null,
    [System.Management.Automation.PowerShell]::Create()
).CompletionMatches

$candidates | ForEach-Object {
    [pscustomobject]@{
        CompletionText = $_.CompletionText
        ResultType = $_.ResultType.ToString()
        ToolTip = $_.ToolTip
    }
}