It's not clear to me if dropping support for this functionality was intentional.

Chain of events:

- #21689 removed test coverage due to a misunderstanding due, I believe, to this functionality being generally supported by all platforms except macOS which does not and returns a different format
- #21756 removed support and caused this regression
- #21690 restores the test coverage that would have caught this regression

Currently, neither the test coverage before #21689 nor the coverage restored by #21690 pass since the merge of #21756.

{"2001:db8:0:0::1", "2001:db8::1"},
        {"2001:db8:0:0:aaaa::1", "2001:db8::aaaa:0:0:1"},
        {"2001:db8:0:1:1:1:1:1", "2001:db8:0:1:1:1:1:1"},
        {"2001:db8:0::1", "2001:db8::1"},
        {"2001:db8:85a3:0:0:8a2e:370:7334", "2001:db8:85a3::8a2e:370:7334"},
        {"2001:db8::0:1", "2001:db8::1"},
        {"2001:db8::0:1:0:0:1", "2001:db8::1:0:0:1"},
        {"2001:DB8::1", "2001:db8::1"},
        {"2001:db8::1", "2001:db8::1"},
        {"2001:db8::1:0:0:1", "2001:db8::1:0:0:1"},
        {"2001:db8::1:1:1:1:1", "2001:db8:0:1:1:1:1:1"},
        {"2001:db8::aaaa:0:0:1", "2001:db8::aaaa:0:0:1"},
        {"2001:db8:aaaa:bbbb:cccc:dddd:0:1", "2001:db8:aaaa:bbbb:cccc:dddd:0:1"},
        {"2001:db8:aaaa:bbbb:cccc:dddd::1", "2001:db8:aaaa:bbbb:cccc:dddd:0:1"},
        {"2001:db8:aaaa:bbbb:cccc:dddd:eeee:0001", "2001:db8:aaaa:bbbb:cccc:dddd:eeee:1"},
        {"2001:db8:aaaa:bbbb:cccc:dddd:eeee:001", "2001:db8:aaaa:bbbb:cccc:dddd:eeee:1"},
        {"2001:db8:aaaa:bbbb:cccc:dddd:eeee:01", "2001:db8:aaaa:bbbb:cccc:dddd:eeee:1"},
        {"2001:db8:aaaa:bbbb:cccc:dddd:eeee:1", "2001:db8:aaaa:bbbb:cccc:dddd:eeee:1"},
        {"2001:db8:aaaa:bbbb:cccc:dddd:eeee:aaaa", "2001:db8:aaaa:bbbb:cccc:dddd:eeee:aaaa"},
        {"2001:db8:aaaa:bbbb:cccc:dddd:eeee:AAAA", "2001:db8:aaaa:bbbb:cccc:dddd:eeee:aaaa"},
        {"2001:db8:aaaa:bbbb:cccc:dddd:eeee:AaAa", "2001:db8:aaaa:bbbb:cccc:dddd:eeee:aaaa"},
    };
    for (const auto& [input_address, expected_canonical_representation_output] : canonical_representations_ipv6) {
        CNetAddr net_addr;
        BOOST_REQUIRE(LookupHost(input_address, net_addr, false));
        BOOST_REQUIRE(net_addr.IsIPv6());
        BOOST_CHECK_EQUAL(net_addr.ToString(), expected_canonical_representation_output);
    }
}
BOOST_AUTO_TEST_CASE(cnetaddr_serialize_v1)