rust/src/test/run-pass/log-knows-the-names-of-variants-in-std.rs

use std;
import std::list;

enum foo {
  a(uint),
  b(~str),
}

fn check_log<T>(exp: ~str, v: T) {
    assert exp == fmt!{"%?", v};
}

fn main() {
    let x = list::from_vec(~[a(22u), b(~"hi")]);
    let exp = ~"@cons(a(22), @cons(b(~\"hi\"), @nil))";
    assert fmt!{"%?", x} == exp;
    check_log(exp, x);
}