Need to add "^~" to give this match a higher priority than regex location blocks.
location ^~ /test/ {
return 404;
}
Otherwise you will be in some tricky situation. For example, if you have another location block such as
location ~ \.php$ {
...
}
and someone sends a request to http://your_domain.com/test/bad.php, that regex location block will be picked by nginx to serve the request. Obviously it's not what you want. So be sure to put "^~" in that location block!