use anyhow::{anyhow, Error};
fn error() -> Error {
    anyhow!(0).context(1).context(2).context(3)
}
#[test]
fn test_iter() {
    let e = error();
    let mut chain = e.chain();
    assert_eq!("3", chain.next().unwrap().to_string());
    assert_eq!("2", chain.next().unwrap().to_string());
    assert_eq!("1", chain.next().unwrap().to_string());
    assert_eq!("0", chain.next().unwrap().to_string());
    assert!(chain.next().is_none());
    assert!(chain.next_back().is_none());
}
#[test]
fn test_rev() {
    let e = error();
    let mut chain = e.chain().rev();
    assert_eq!("0", chain.next().unwrap().to_string());
    assert_eq!("1", chain.next().unwrap().to_string());
    assert_eq!("2", chain.next().unwrap().to_string());
    assert_eq!("3", chain.next().unwrap().to_string());
    assert!(chain.next().is_none());
    assert!(chain.next_back().is_none());
}
#[test]
fn test_len() {
    let e = error();
    let mut chain = e.chain();
    assert_eq!(4, chain.len());
    assert_eq!("3", chain.next().unwrap().to_string());
    assert_eq!(3, chain.len());
    assert_eq!("0", chain.next_back().unwrap().to_string());
    assert_eq!(2, chain.len());
    assert_eq!("2", chain.next().unwrap().to_string());
    assert_eq!(1, chain.len());
    assert_eq!("1", chain.next_back().unwrap().to_string());
    assert_eq!(0, chain.len());
    assert!(chain.next().is_none());
}