Ticket #15800: network-tab-tester-15800.php

<?php
/**
 * Plugin Name: Network Tab Patch Test Case
 * Plugin URI:  https://core.trac.wordpress.org/ticket/15800
 * Description: Test use case for the patch to allow extension of network site tabs
 */

if ( ! is_network_admin() ) {
        return NULL;
}

add_action( 'network_admin_menu', 'ticket15800_network_site_tabs' );
function ticket15800_network_site_tabs() {

        add_filter( 'network_edit_site_tabs', 'ticket15800_filter_network_site_tabs', 10, 3 );

        if ( isset( $_GET[ 'page' ] ) && 'test_tab' === $_GET[ 'page' ] ) {
                global $_registered_pages;
                // Set true, that you have the rights to see the content
                $_registered_pages[ 'admin_page_test_tab' ] = TRUE;

                add_action( 'admin_page_test_tab', 'ticket15800_callback' );
        }
}

/**
 * Add new tab
 *
 * @param $tabs
 * @param $id
 * @param $pagenow
 *
 * @return mixed
 */
function ticket15800_filter_network_site_tabs( $tabs, $id, $pagenow ) {

        $tabs[ 'test15800-tab' ] = array(
                'label'             => __( 'Test', 'textdomain' ),
                'menu-slug'         => 'test_tab',
                'callback-function' => 'ticket15800_callback',
        );

        return $tabs;
}

/**
 * Get the new site settings page
 *
 * @return void
 */
function ticket15800_callback() {

        if ( isset( $_REQUEST[ 'id' ] ) ) {
                $id = intval( $_REQUEST[ 'id' ] );
        } else {
                $id = 0;
        }

        ?>
        <div class="wrap">
                <h2>Test for Ticket 15800</h2>

                <h3 class="nav-tab-wrapper">
                        <?php network_edit_site_tabs( $id ); ?>
                </h3>

                <p>Content ...</p>
        </div>
<?php
}