Is there a way to check if Proxy has been actually used? When using browser for example it will print if it fails to use Proxy.
But is there something like this for HTTP-CLIENT Proxy?
Not that I know of. You'll need to tunnel through the proxy to really check the connection. I either do a proxy checker site to make sure nothing is leaking, or I just do the simple GET request against the site(s) I'm working with/on.