code:

server {
    listen      443 ssl http2 default_server;
    server_name example.com [url]www.example.com;[/url]

    ssl_certificate     /config/example.com-letsencrypt.pem;
    ssl_certificate_key /config/example.com.key;

    ...
}

server {
    listen      443 ssl http2;
    server_name test.example.com;

    ssl_certificate     /config/test.example.com-letsencrypt.pem;
    ssl_certificate_key /config/test.example.com.key;

    ...
}