tokio/tests/rt_current_thread.rs


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#![warn(rust_2018_idioms)]

use tokio::runtime::Runtime;
use tokio::sync::oneshot;
use tokio_test::{assert_err, assert_ok};

use std::thread;
use std::time::Duration;

#[test]
fn spawned_task_does_not_progress_without_block_on() {
    let (tx, mut rx) = oneshot::channel();

    let mut rt = rt();

    rt.spawn(async move {
        assert_ok!(tx.send("hello"));
    });

    thread::sleep(Duration::from_millis(50));

    assert_err!(rx.try_recv());

    let out = rt.block_on(async { assert_ok!(rx.await) });

    assert_eq!(out, "hello");
}

fn rt() -> Runtime {
    tokio::runtime::Builder::new()
        .current_thread()
        .build()
        .unwrap()
}