About
The Arbitrary
crate lets you construct arbitrary instances of a type.
This crate is primarily intended to be combined with a fuzzer like libFuzzer and cargo-fuzz
or AFL, and to help you turn the raw, untyped byte buffers that they produce into well-typed, valid, structured values. This allows you to combine structure-aware test case generation with coverage-guided, mutation-based fuzzers.
Documentation
Read the API documentation on docs.rs
!
Example
Say you're writing a color conversion library, and you have an Rgb
struct to represent RGB colors. You might want to implement Arbitrary
for Rgb
so that you could take arbitrary Rgb
instances in a test function that asserts some property (for example, asserting that RGB converted to HSL and converted back to RGB always ends up exactly where we started).
Arbitrary
Automatically Deriving Automatically deriving the Arbitrary
trait is the recommended way to implement Arbitrary
for your types.
Automatically deriving Arbitrary
requires you to enable the "derive"
cargo feature:
# Cargo.toml
[dependencies]
arbitrary = { version = "1", features = ["derive"] }
And then you can simply add #[derive(Arbitrary)]
annotations to your types:
// rgb.rs
use arbitrary::Arbitrary;
#[derive(Arbitrary)]
pub struct Rgb {
pub r: u8,
pub g: u8,
pub b: u8,
}
Arbitrary
By Hand
Implementing Alternatively, you can write an Arbitrary
implementation by hand:
// rgb.rs
use arbitrary::{Arbitrary, Result, Unstructured};
#[derive(Copy, Clone, Debug)]
pub struct Rgb {
pub r: u8,
pub g: u8,
pub b: u8,
}
impl<'a> Arbitrary<'a> for Rgb {
fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
let r = u8::arbitrary(u)?;
let g = u8::arbitrary(u)?;
let b = u8::arbitrary(u)?;
Ok(Rgb { r, g, b })
}
}
License
Licensed under dual MIT or Apache-2.0 at your choice.
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this project by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.