> ## Documentation Index
> Fetch the complete documentation index at: https://codspeed.io/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# bencher (libtest) compatibility layer documentation
> A compatibility layer for `bencher`, a port of the unstable libtest benchmarking framework
export const BuildkiteIcon = props => ;
export const GitLabIcon = props => ;
export const GitHubIcon = props => ;
## Overview
`codspeed-bencher-compat` is a Bencher compatibility layer for CodSpeed that
allows seamless integration of Rust's built-in benchmarking framework with
CodSpeed performance measurement.
This crate acts as a drop-in replacement for the standard `bencher` crate,
maintaining your existing benchmark code while enabling CodSpeed integration.
Bencher is a port of the unstable `libtest` benchmarking framework. It is not
recommended for new projects, consider using
[Divan](/reference/codspeed-rust/divan) for new projects as it offers better
ergonomics and features.
## Installation
Install the compatibility layer and rename it to `bencher` to maintain
compatibility with existing code:
```bash theme={null}
cargo add --dev codspeed-bencher-compat --rename bencher
```
This will install the `codspeed-bencher-compat` crate and rename it to `bencher` in your `Cargo.toml`.
This way, you can keep your existing imports and the compatibility layer will take care of the rest.
Using the compatibility layer won't change the behavior of your benchmark suite
and bencher will still run it as usual.
If you prefer, you can also install `codspeed-bencher-compat` as is and change
your imports to use this new crate name.
## Usage
Let's start with the example from the
[Bencher documentation](https://docs.rs/bencher/latest/bencher/), creating a
benchmark suite for 2 simple functions (in `benches/example.rs`):
```rust theme={null}
use bencher::{benchmark_group, benchmark_main, Bencher};
fn a(bench: &mut Bencher) {
bench.iter(|| {
(0..1000).fold(0, |x, y| x + y)
})
}
fn b(bench: &mut Bencher) {
const N: usize = 1024;
bench.iter(|| {
vec![0u8; N]
});
bench.bytes = N as u64;
}
benchmark_group!(benches, a, b);
benchmark_main!(benches);
```
The last step in creating the Bencher benchmark is to add the new benchmark
target in your `Cargo.toml`:
```toml title="Cargo.toml" theme={null}
[[bench]]
name = "example"
harness = false
```
And that's it! You can now run your benchmark suite with CodSpeed:
```shellsession title=terminal icon="square-terminal" theme={null}
$ cargo codspeed build
Finished release [optimized] target(s) in 0.12s
Finished built 1 benchmark suite(s)
$ cargo codspeed run
Collected 1 benchmark suite(s) to run
Running example
Using codspeed-bencher-compat v1.0.0 compatibility layer
NOTICE: codspeed is enabled, but no performance measurement will
be made since it's running in an unknown environment.
Checked: benches/example.rs::a (group: benches)
Checked: benches/example.rs::b (group: benches)
Done running bencher_example
Finished running 1 benchmark suite(s)
```
## Resources
* [Official bencher documentation](https://docs.rs/bencher/latest/bencher/index.html)
* [Official bencher GitHub repository](https://github.com/bluss/bencher)
