test script to create a user through Drupal's user resource

user_create.php

<?php

$base_url = 'http://YOUR.SITE.HERE/api';

// Login
$login_data = array(
        'username' => 'YOUR_USER',
        'password' => 'YOUR_PASSWORD',
);

$req = new HttpRequest("$base_url/user/login.json", HttpRequest::METH_POST);
#$req->setRawPostData(json_encode($login_data));
$req->setRawPostData(json_encode($login_data));
$req->setContentType('application/json');
$req->send();
if ($req->getResponseCode() != 200) {
    echo "login failed\n";
    print_r($req);
    exit;
}
$response = $req->getResponseBody();
$response = json_decode($response);
$session_cookie = array($response->session_name => $response->sessid);


$user = array(
        'name' => 'quux' . microtime(1),
        'mail'=> 'quux'.microtime(1).'@example.com',
        'pass'=>'quuxpass',
);
$json_user = json_encode($user);

$req = new HttpRequest("$base_url/user.json", HttpRequest::METH_POST);
$req->addCookies($session_cookie);
$req->setRawPostData($json_user);
$req->setContentType('application/json');
$req->send();
if ($req->getResponseCode() != 200) {
    echo "create failed:\n";
    print_r($req);
    echo "\n";
}
print_r($req);