You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: lib.rs
    path of file: ./repos/holochain/crates/test_utils/wasm/wasm_workspace/random_bytes/src
    
    the code of the file until where you have to start completion: use hdk::prelude::*;

#[hdk_extern]
fn random_bytes(bytes: u32) -> ExternResult<Bytes> {
    hdk::prelude::random_bytes(bytes)
}

#[hdk_extern]
fn rand_random_bytes(bytes: u32) -> ExternResult<Bytes> {
    use rand::Rng;
    let mut bytes = vec![0; bytes as usize];
    rand::rngs::OsRng.fill(&mut bytes[..]);
    Ok(Bytes::from(bytes))
}

#[cfg(all(test, feature = "mock"))]
mod tests {
    #[test]
    fn ran
    
    fn random_bytes_smoke() {
        let mut mock_hdk = hdk::prelude::MockHdkT::new();

        let input = 1;
        let output = hdk::prelude::Bytes::from(vec![4_u8]);
        let output_closure = output.clone();
        mock_hdk
            .expect_random_bytes()
            .with(hdk::prelude::mockall::predicate::eq(input))
            .times(1)
            .return_once(move |_| Ok(output_closure));

        hdk::prelude::set_hdk(mock_hdk);

        let result = super::random_bytes(input);

        assert_eq!(result, Ok(output));
    }