tweet.php

require 'vendor/TwitterAPIExchange.php';

$settings = array(
    'oauth_access_token' => "",
    'oauth_access_token_secret' => "",
    'consumer_key' => "",
    'consumer_secret' => ""
);

$url = "https://api.twitter.com/1.1/statuses/update.json";

$postfields = array('status' => 'test');

$requestMethod = 'POST';

$twitter = new TwitterAPIExchange($settings);
$response =  $twitter->buildOauth($url, $requestMethod)
                 ->setPostfields($postfields)
                 ->performRequest();

echo '<pre style="color:black;">';
var_dump(json_decode($response));
echo '</pre>';