Helper\Test::server PHP Method

    public function server($test, $request_method, $query_parameters = array(), $data = array())
    {
        $this->curl->setHeader('X-DEBUG-TEST', $test);
        $request_method = strtolower($request_method);
        if (is_array($data) && empty($data)) {
            $this->curl->{$request_method}(self::TEST_URL, $query_parameters);
        } else {
            $this->curl->{$request_method}(self::TEST_URL, $query_parameters, $data);
        }
        return $this->curl->response;
    }

 public function testDownloadCallback()
 {
     // Upload a file.
     $upload_file_path = Helper\get_png();
     $upload_test = new Test();
     $upload_test->server('upload_response', 'POST', array('image' => '@' . $upload_file_path));
     $uploaded_file_path = $upload_test->curl->response->file_path;
     // Download the file.
     $download_callback_called = false;
     $multi_curl = new MultiCurl();
     $multi_curl->setHeader('X-DEBUG-TEST', 'download_response');
     $multi_curl->addDownload(Test::TEST_URL . '?' . http_build_query(array('file_path' => $uploaded_file_path)), function ($instance, $fh) use(&$download_callback_called) {
         PHPUnit_Framework_Assert::assertFalse($download_callback_called);
         PHPUnit_Framework_Assert::assertInstanceOf('Curl\\Curl', $instance);
         PHPUnit_Framework_Assert::assertTrue(is_resource($fh));
         PHPUnit_Framework_Assert::assertEquals('stream', get_resource_type($fh));
         PHPUnit_Framework_Assert::assertGreaterThan(0, strlen(stream_get_contents($fh)));
         PHPUnit_Framework_Assert::assertEquals(0, strlen(stream_get_contents($fh)));
         PHPUnit_Framework_Assert::assertTrue(fclose($fh));
         $download_callback_called = true;
     });
     $multi_curl->start();
     $this->assertTrue($download_callback_called);
     // Remove server file.
     $this->assertEquals('true', $upload_test->server('upload_cleanup', 'POST', array('file_path' => $uploaded_file_path)));
     unlink($upload_file_path);
     $this->assertFalse(file_exists($upload_file_path));
     $this->assertFalse(file_exists($uploaded_file_path));
 }