macro_rules! not_err {
    ($e:expr) => (match $e {
        Ok(e) => e,
        Err(e) => panic!("{} failed with {:?}", stringify!($e), e),
    })
}

macro_rules! is_err {
    ($e:expr) => (match $e {
        Ok(e) => panic!("{} did not return with an error, but with {:?}", stringify!($e), e),
        Err(e) => e,
    })
}

macro_rules! assert_matches {
    ($e: expr, $p: pat) => (assert_matches!($e, $p, ()));
    ($e: expr, $p: pat, $f: expr) => (match $e {
        $p => $f,
        e => {
            panic!(
                "{}: Expected pattern {} \ndoes not match {:?}",
                stringify!($e), stringify!($p), e
            )
        }
    })
}