tor-netdoc: Add test for default deny encoding of AddrPolicy

        let mut enc = NetdocEncoder::default();

        wrapper.encode_unsigned(&mut enc).unwrap();

        assert_eq!(RULES, enc.finish().unwrap());

        // Test default deny.

        let accept_all = {

            let mut ap = AddrPolicy::new();

            ap.push(RuleKind::Accept, AddrPortPattern::new_all());

            ap

        };

        let reject_all = {

            let mut ap = AddrPolicy::new();

            ap.push(RuleKind::Reject, AddrPortPattern::new_all());

            ap

        };

        let tests = [

            (accept_all.clone(), "accept *:*"), // do not add default deny to existing

            (reject_all.clone(), "reject *:*"), // do not add default deny to existing

            (AddrPolicy::new(), "reject *:*"),  // add default deny to empty

        ];

        for (input, expected_tail) in tests {

            let mut enc = NetdocEncoder::default();

            Wrapper {

                intro: (),

                ipv4_policy: input,

            }

            .encode_unsigned(&mut enc)

            .unwrap();

            assert_eq!(expected_tail, enc.finish().unwrap().lines().last().unwrap());

        }

    }

}