How to correctly define test-only dependencies in Rust/Cargo?

Hello colleagues! I started learning Rust and encountered a problem when writing tests. I need to use the `rand` crate to generate random data in tests, but I don't want it to be a dependency in the final build. I added `rand` to the `[dependencies]` section in `Cargo.toml`, but this increases the binary size and compilation time. How do I properly specify dependencies only for tests? I tried writing this: ```toml [dev-dependencies] rand = "0.8" ``` But then in tests I can't import: `use rand::Rng;` — the compiler complains that the crate is not found. I also tried using `#[cfg(test)]` for conditional compilation, but I don't understand how to apply it correctly to dependencies. Please advise how to organize test-only dependencies in Rust/Cargo.