How do I use panic::catch_unwind with asynchronous code?

Question

When working with synchronous code, I can use panic::catch_unwind like this:

#[actix_rt::test]
async fn test_sync() -> Result<(), Error> {
    println!("before catch_unwind");
    let sync_result = panic::catch_unwind(|| {
        println!("inside sync catch_unwind");
        panic!("this is error")
    });
    println!("after catch_unwind");

    assert!(sync_result.is_ok());

    Ok(())
}

How do I do the same when working with async code that is executed inside the catch_unwind block? I can't figure out how to run the block while also being able to run some code after the block and finally assert the result.

This is what I have so far:

#[actix_rt::test]
async fn test_async() -> Result<(), Error> {
    println!("before catch_unwind");
    let async_result = panic::catch_unwind(|| async {
        println!("inside async catch_unwind");
        panic!("this is error")
    }).await;
    println!("after catch_unwind");

    assert!(async_result.is_ok());

    Ok(())
}

Answer 1

I would not attempt to use them directly. Instead, use FutureExt::catch_unwind and StreamExt::catch_unwind.

use futures::FutureExt; // 0.3.5

#[tokio::test]
async fn test_async() -> Result<(), Box<dyn std::error::Error>> {
    println!("before catch_unwind");

    let may_panic = async {
        println!("inside async catch_unwind");
        panic!("this is error")
    };

    let async_result = may_panic.catch_unwind().await;

    println!("after catch_unwind");

    assert!(async_result.is_ok());

    Ok(())
}