wordpress bulk edit action not apply for all posts selected

I want to write a plugin for wordpress that it can when i edit bulk action, add a tag to all posts selected. this is a sample that i write, but it just add a tag to one post While I want this apply for all posts selected!

add_action('bulk_edit_custom_box', 'bulk_test');
function bulk_test(){
$post_ID = get_the_ID();
wp_set_post_tags($post_ID,'test',true );
}

via Chebli Mohamed