Drop in benchmark snippet for Rust projects that want to use cargo-bench on nightly.

cargo-bench-template.rs

// NB. this must be placed at the top of the module.
#![feature(test)]

#[cfg(test)]
mod tests {
    extern crate test;

    use super::*;
    use test::{black_box, Bencher};

    #[bench]
    fn bench_x(b: &mut Bencher) {
        b.iter(|| {
            for i in 1..2 {
                black_box(());
            }
        });
    }
}