Working example of a WordPress Loop Shortcode

functions.php

<?php 
/**
 *
 *
 */
if (!function_exists('footer_get_latest_post')) {
    function footer_get_latest_post() {
        ob_start();
        $footerPost = '';
        $args = array('posts_per_page' => 1 );
        $recent_posts = new WP_Query($args);
        while( $recent_posts->have_posts() ) {
            $recent_posts->the_post();
            $footerPost = '<div class="footer-post-thumb">' . the_post_thumbnail('thumbnail') . '</div>';
            $footerPost .= '<div class="footer-post-content"><h3>' . the_title() . '</h3>';
            $footerPost .= the_content() . '</div>';
        }
        wp_reset_query();
        //return $footerPost;
        $output = ob_get_contents();
        ob_end_clean();

        return $output;
    }
}
add_shortcode('FooterLatestPost', 'footer_get_latest_post');