#[test]
async fn test_async_closure_retry_with_not_retryable_error() {
    let error_times = Mutex::new(0);

    let f = async || {
        let mut x = error_times.lock().await;
        *x += 1;
        Err::<(), anyhow::Error>(anyhow::anyhow!("not retryable"))
    };

    let backoff = ExponentialBuilder::default().with_min_delay(Duration::from_millis(1));
    let result = f
        .retry(backoff)
        // Only retry If error message is `retryable`
        .when(|e| e.to_string() == "retryable")
        .await;

    assert!(result.is_err());
    assert_eq!("not retryable", result.unwrap_err().to_string());
    // `f` always returns error "not retryable", so it should be executed
    // only once.
    assert_eq!(*error_times.lock().await, 1);
}