RestClient::execute PHP Method

    public function execute($url, $method = 'GET', $parameters = [], $headers = [])
    {
        $client = clone $this;
        $client->url = $url;
        $client->handle = curl_init();
        $curlopt = [CURLOPT_HEADER => TRUE, CURLOPT_RETURNTRANSFER => TRUE, CURLOPT_USERAGENT => $client->options['user_agent']];
        if ($client->options['username'] && $client->options['password']) {
            $curlopt[CURLOPT_USERPWD] = sprintf("%s:%s", $client->options['username'], $client->options['password']);
        }
        if (count($client->options['headers']) || count($headers)) {
            $curlopt[CURLOPT_HTTPHEADER] = [];
            $headers = array_merge($client->options['headers'], $headers);
            foreach ($headers as $key => $values) {
                foreach (is_array($values) ? $values : [$values] as $value) {
                    $curlopt[CURLOPT_HTTPHEADER][] = sprintf("%s:%s", $key, $value);
                }
            }
        }
        if ($client->options['format']) {
            $client->url .= '.' . $client->options['format'];
        }
        // Allow passing parameters as a pre-encoded string (or something that
        // allows casting to a string). Parameters passed as strings will not be
        // merged with parameters specified in the default options.
        if (is_array($parameters)) {
            $parameters = array_merge($client->options['parameters'], $parameters);
            $parameters_string = $client->format_query($parameters);
        } else {
            $parameters_string = (string) $parameters;
        }
        if (strtoupper($method) == 'POST') {
            $curlopt[CURLOPT_POST] = TRUE;
            $curlopt[CURLOPT_POSTFIELDS] = $parameters_string;
        } elseif (strtoupper($method) != 'GET') {
            $curlopt[CURLOPT_CUSTOMREQUEST] = strtoupper($method);
            $curlopt[CURLOPT_POSTFIELDS] = $parameters_string;
        } elseif ($parameters_string) {
            $client->url .= strpos($client->url, '?') ? '&' : '?';
            $client->url .= $parameters_string;
        }
        if ($client->options['base_url']) {
            if ($client->url[0] != '/' && substr($client->options['base_url'], -1) != '/') {
                $client->url = '/' . $client->url;
            }
            $client->url = $client->options['base_url'] . $client->url;
        }
        $curlopt[CURLOPT_URL] = $client->url;
        if ($client->options['curl_options']) {
            // array_merge would reset our numeric keys.
            foreach ($client->options['curl_options'] as $key => $value) {
                $curlopt[$key] = $value;
            }
        }
        curl_setopt_array($client->handle, $curlopt);
        $client->parse_response(curl_exec($client->handle));
        $client->info = (object) curl_getinfo($client->handle);
        $client->error = curl_error($client->handle);
        curl_close($client->handle);
        return $client;
    }

 public function test_json_patch()
 {
     global $TEST_SERVER_URL;
     $api = new RestClient();
     $result = $api->execute($TEST_SERVER_URL, 'PATCH', "{\"foo\":\"bar\"}", array('X-HTTP-Method-Override' => 'PATCH', 'Content-Type' => 'application/json-patch+json'));
     $response_json = $result->decode_response();
     $this->assertEquals('application/json-patch+json', $response_json->headers->{"Content-Type"});
     $this->assertEquals('PATCH', $response_json->headers->{"X-HTTP-Method-Override"});
     $this->assertEquals('PATCH', $response_json->SERVER->REQUEST_METHOD);
     $this->assertEquals("{\"foo\":\"bar\"}", $response_json->body);
 }