Jetpack_Subscriptions::init PHP Method

    static function init()
    {
        static $instance = false;
        if (!$instance) {
            $instance = new Jetpack_Subscriptions();
        }
        return $instance;
    }

 public function test_sync_jetpack_published_post_should_set_dont_send_to_subscribers_flag()
 {
     Jetpack_Options::update_option('active_modules', array('subscriptions'));
     require_once JETPACK__PLUGIN_DIR . '/modules/subscriptions.php';
     Jetpack_Subscriptions::init();
     wp_update_post(array('ID' => $this->post->ID, 'post_status' => 'draft'));
     update_post_meta($this->post->ID, '_jetpack_dont_email_post_to_subs', 1);
     wp_publish_post($this->post->ID);
     $this->sender->do_sync();
     $post_flags = $this->server_event_storage->get_most_recent_event('jetpack_published_post')->args[1];
     $this->assertEquals($post_flags['_jetpack_dont_email_post_to_subs'], 1);
 }