Proxy pass with Regex

I am trying to use nginx to bypass corp. firewall.
What Im doing is to

location /test/sometext {
proxy_pass http://sometext;
}

for example

location /test/nginx.org {
proxy_pass http://nginx.org;
}

This needs to be done by pattern match in order to generalize, but using rewrite method, the url becomes http://nginx.org directly, which my vm has no access to it.