use anyhow::{bail, Context, Result};
fn f() -> Result<()> {
    bail!("oh no!");
}
fn g() -> Result<()> {
    f().context("f failed")
}
fn h() -> Result<()> {
    g().context("g failed")
}
const EXPECTED_DEBUG_F: &str = "\
oh no!
Backtrace disabled; run with RUST_LIB_BACKTRACE=1 environment variable to display a backtrace
";
const EXPECTED_DEBUG_G: &str = "\
f failed
Caused by:
    oh no!
Backtrace disabled; run with RUST_LIB_BACKTRACE=1 environment variable to display a backtrace
";
const EXPECTED_DEBUG_H: &str = "\
g failed
Caused by:
    0: f failed
    1: oh no!
Backtrace disabled; run with RUST_LIB_BACKTRACE=1 environment variable to display a backtrace
";
#[test]
fn test_display() {
    assert_eq!("g failed", h().unwrap_err().to_string());
}
#[test]
fn test_debug() {
    assert_eq!(EXPECTED_DEBUG_F, format!("{:?}", f().unwrap_err()));
    assert_eq!(EXPECTED_DEBUG_G, format!("{:?}", g().unwrap_err()));
    assert_eq!(EXPECTED_DEBUG_H, format!("{:?}", h().unwrap_err()));
}