WooCommerce single product - navigate to the next or previous product.

gistfile1.txt

//add_action( 'woocommerce_before_single_product', 'add_custom_text_before_product_title' );
 add_shortcode( 'scnextprev', 'productnextprev_shortcode' );
function productnextprev_shortcode(){
 
echo '<div class="prev_next_buttons">';
 
   // 'product_cat' will make sure to return next/prev from current category
        $previous = next_post_link('%link', '&larr; %title', TRUE, ' ', 'product_cat');
 		$next = previous_post_link('%link', '%title &rarr;', TRUE, ' ', 'product_cat');
 
   echo $previous;
   echo $next;
    
echo '</div>';
}