JSON API fetch tests with Powershell

JSONFetch.ps1

function ConvertTo-JSON([object] $item){
    add-type -assembly system.web.extensions
    $ps_js=new-object system.web.script.serialization.javascriptSerializer
    return $ps_js.Serialize($item)
}


function ConvertFrom-JSON([object] $item){
    add-type -assembly system.web.extensions
    $ps_js=new-object system.web.script.serialization.javascriptSerializer
    return , $ps_js.DeserializeObject($item)
}

function Invoke-WebRequest($url, $method, $data, $contenttype) {
    $request = [System.Net.WebRequest]::Create($url)
    if ($method -eq "POST") {
        $request.Method = "POST"
        $request.ContentType = (
            {$($contenttype)},
            {'application/x-www-form-urlencoded'}
        )[!$contenttype -eq $null]
        $reqstream = $request.GetRequestStream()
        $writer = new-object System.IO.StreamWriter($reqstream)
        $writer.Write($data)
    }
    $res = $request.GetResponse()
    $stream = $res.GetResponseStream()
    $reader = new-object System.IO.StreamReader($stream)
    $output = $reader.ReadToEnd()
    return $output
}

$r = Invoke-WebRequest 'http://httpbin.org/post' -method 'POST' -data 'test=123'
$json = ConvertFrom-JSON $r
$json