Cloudinary::api_sign_request PHP Method

    public static function api_sign_request($params_to_sign, $api_secret)
    {
        $params = array();
        foreach ($params_to_sign as $param => $value) {
            if (isset($value) && $value !== "") {
                if (!is_array($value)) {
                    $params[$param] = $value;
                } else {
                    if (count($value) > 0) {
                        $params[$param] = implode(",", $value);
                    }
                }
            }
        }
        ksort($params);
        $join_pair = function ($key, $value) {
            return $key . "=" . $value;
        };
        $to_sign = implode("&", array_map($join_pair, array_keys($params), array_values($params)));
        return sha1($to_sign . $api_secret);
    }

 public function test_upload()
 {
     $result = Cloudinary\Uploader::upload("tests/logo.png");
     $this->assertEquals($result["width"], 241);
     $this->assertEquals($result["height"], 51);
     $expected_signature = Cloudinary::api_sign_request(array("public_id" => $result["public_id"], "version" => $result["version"]), Cloudinary::config_get("api_secret"));
     $this->assertEquals($result["signature"], $expected_signature);
 }