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use futures::channel::oneshot;
use futures::future::{self, Future, FutureExt, TryFutureExt};
use futures::task::{Context, Poll};
use futures_test::future::FutureTestExt;
use pin_project::pin_project;
use std::pin::Pin;
use std::sync::mpsc;
#[test]
fn map_ok() {
// The closure given to `map_ok` should have been dropped by the time `map`
// runs.
let (tx1, rx1) = mpsc::channel::<()>();
let (tx2, rx2) = mpsc::channel::<()>();
future::ready::<Result<i32, i32>>(Err(1))
.map_ok(move |_| {
let _tx1 = tx1;
panic!("should not run");
})
.map(move |_| {
assert!(rx1.recv().is_err());
tx2.send(()).unwrap()
})
.run_in_background();
rx2.recv().unwrap();
}
#[test]
fn map_err() {
// The closure given to `map_err` should have been dropped by the time `map`
// runs.
let (tx1, rx1) = mpsc::channel::<()>();
let (tx2, rx2) = mpsc::channel::<()>();
future::ready::<Result<i32, i32>>(Ok(1))
.map_err(move |_| {
let _tx1 = tx1;
panic!("should not run");
})
.map(move |_| {
assert!(rx1.recv().is_err());
tx2.send(()).unwrap()
})
.run_in_background();
rx2.recv().unwrap();
}
#[pin_project]
struct FutureData<F, T> {
_data: T,
#[pin]
future: F,
}
impl<F: Future, T: Send + 'static> Future for FutureData<F, T> {
type Output = F::Output;
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<F::Output> {
self.project().future.poll(cx)
}
}
#[test]
fn then_drops_eagerly() {
let (tx0, rx0) = oneshot::channel::<()>();
let (tx1, rx1) = mpsc::channel::<()>();
let (tx2, rx2) = mpsc::channel::<()>();
FutureData { _data: tx1, future: rx0.unwrap_or_else(|_| panic!()) }
.then(move |_| {
assert!(rx1.recv().is_err()); // tx1 should have been dropped
tx2.send(()).unwrap();
future::ready(())
})
.run_in_background();
assert_eq!(Err(mpsc::TryRecvError::Empty), rx2.try_recv());
tx0.send(()).unwrap();
rx2.recv().unwrap();
}
#[test]
fn and_then_drops_eagerly() {
let (tx0, rx0) = oneshot::channel::<Result<(), ()>>();
let (tx1, rx1) = mpsc::channel::<()>();
let (tx2, rx2) = mpsc::channel::<()>();
FutureData { _data: tx1, future: rx0.unwrap_or_else(|_| panic!()) }
.and_then(move |_| {
assert!(rx1.recv().is_err()); // tx1 should have been dropped
tx2.send(()).unwrap();
future::ready(Ok(()))
})
.run_in_background();
assert_eq!(Err(mpsc::TryRecvError::Empty), rx2.try_recv());
tx0.send(Ok(())).unwrap();
rx2.recv().unwrap();
}
#[test]
fn or_else_drops_eagerly() {
let (tx0, rx0) = oneshot::channel::<Result<(), ()>>();
let (tx1, rx1) = mpsc::channel::<()>();
let (tx2, rx2) = mpsc::channel::<()>();
FutureData { _data: tx1, future: rx0.unwrap_or_else(|_| panic!()) }
.or_else(move |_| {
assert!(rx1.recv().is_err()); // tx1 should have been dropped
tx2.send(()).unwrap();
future::ready::<Result<(), ()>>(Ok(()))
})
.run_in_background();
assert_eq!(Err(mpsc::TryRecvError::Empty), rx2.try_recv());
tx0.send(Err(())).unwrap();
rx2.recv().unwrap();
}