How do you serve static files from an nginx server acting as a reverse proxy for a nodejs server?

My current nginx config is this:

upstream nodejs {
    server 127.0.0.1:3000;
}

server {
    listen 8080;
    server_name localhost;
    root ~/workspace/test/app;
    index index.html;

    error_log /usr/local/var/log/nginx/error.log;
    access_log /usr/local/var/log/nginx/access.log;

    location / {
        proxy_pass http://nodejs;
        proxy_set_header Host $host ; 
        proxy_set_header X-Real-IP $remote_addr; 
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }
}

I'm very very new to nginx, but at the very least I know that nginx is better than node/express at serving static files. How can I configure the server so that nginx serves the static files?