diff --git a/docs/getting-started/new-project-guide/rust_lang.md b/docs/getting-started/new-project-guide/rust_lang.md index c28dd7618..8a3b59620 100644 --- a/docs/getting-started/new-project-guide/rust_lang.md +++ b/docs/getting-started/new-project-guide/rust_lang.md @@ -27,6 +27,52 @@ fuzz` tool will build code with required compiler flags as well as link to the correct libFuzzer on OSS-Fuzz itself. Note that using `cargo fuzz` also makes it quite easy to run the fuzzers locally yourself if you get a failing test case! + +### Writing fuzzers using a test-style strategy + +In Rust you will often have tests written in a way so they are only +compiled into the final binary when build in test-mode. This is, achieved by +wrapping your test code in `cfg(test)`, e.g. +```rust +#[cfg(test)] +mod tests { + use super::*; + + ... +``` + +Cargo-fuzz automatically enables the `fuzzing` feature, which means you can +follow a similar strategy to writing fuzzers as you do when writing tests. +Specifically, you can create modules wrapped in the `fuzzing` feature: +```rust +#[cfg(fuzzing)] +pub mod fuzz_logic { + use super::*; + + ... +``` +and then call the logic within `fuzz_logic` from your fuzzer. + +Furthermore, within your `.toml` files, you can then specify fuzzing-specific +depedencies by wrapping them as follows: +``` +[target.'cfg(fuzzing)'.dependencies] +``` +similar to how you wrap test-dependencies as follows: +``` +[dev-dependencies] +``` + +Finally, you can also combine the testing logic you have and the fuzz logic. This +can be achieved simply by using +```rust +#[cfg(any(test, fuzzing))] +``` + +A project that follows this structure is Linkerd2-proxy and the project files can be +seen [here](https://github.com/google/oss-fuzz/tree/master/projects/linkerd2-proxy). + + ## Project files First you'll want to follow the [setup instructions for `cargo fuzz`