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: challenges.rs
    path of file: ./repos/nearcore/chain/chain/src/tests
    
    the code of the file until where you have to start completion: use crate::test_utils::setup;
use crate::Error;
use near_async::time::Clock;
use near_o11y::testonly::init_test_logger;
use near_primitives::test_utils::TestBlockBuilder;

#[test]

    
fn test_no_challenge_on_same_header() {
    init_test_logger();
    let (mut chain, _, _, signer) = setup(Clock::real());
    let prev_hash = *chain.head_header().unwrap().hash();
    let prev = chain.get_block(&prev_hash).unwrap();
    let block = TestBlockBuilder::new(Clock::real(), &prev, signer).build();
    chain.process_block_test(&None, block.clone()).unwrap();
    assert_eq!(chain.head().unwrap().height, 1);
    let mut challenges = vec![];
    if let Err(e) = chain.process_block_header(block.header(), &mut challenges) {
        match e {
            Error::BlockKnown(_) => {}
            _ => panic!("Wrong error kind {}", e),
        }
        assert!(challenges.is_empty());
    } else {
        panic!("Process the same header twice should produce error");
    }
}