Trait futures_test::future::FutureTestExt

pub trait FutureTestExt: Future {
    fn assert_unmoved(self) -> AssertUnmoved<Self>
    where
        Self: Sized,
    { ... }
    fn pending_once(self) -> PendingOnce<Self>
    where
        Self: Sized,
    { ... }
    fn run_in_background(self)
    where
        Self: Sized + Send + 'static,
        Self::Output: Send,
    { ... }
    fn interleave_pending(self) -> InterleavePending<Self>
    where
        Self: Sized,
    { ... }
}

Additional combinators for testing futures.

Provided methods

Important traits for AssertUnmoved<Fut>

impl<Fut: Future> Future for AssertUnmoved<Fut> type Output = Fut::Output;

fn assert_unmoved(self) -> AssertUnmoved<Self> where
    Self: Sized, 

Asserts that the given is not moved after being polled.

A check for movement is performed each time the future is polled and when Drop is called.

Aside from keeping track of the location at which the future was first polled and providing assertions, this future adds no runtime behavior and simply delegates to the child future.

Important traits for PendingOnce<Fut>

impl<Fut: Future> Future for PendingOnce<Fut> type Output = Fut::Output;

fn pending_once(self) -> PendingOnce<Self> where
    Self: Sized, 

Introduces one Poll::Pending before polling the given future.

Examples

use futures::task::Poll;
use futures::future::FutureExt;
use futures_test::task::noop_context;
use futures_test::future::FutureTestExt;
use futures::pin_mut;

let future = (async { 5 }).pending_once();
pin_mut!(future);

let mut cx = noop_context();

assert_eq!(future.poll_unpin(&mut cx), Poll::Pending);
assert_eq!(future.poll_unpin(&mut cx), Poll::Ready(5));

fn run_in_background(self) where
    Self: Sized + Send + 'static,
    Self::Output: Send, 

Runs this future on a dedicated executor running in a background thread.

Examples

use futures::channel::oneshot;
use futures_test::future::FutureTestExt;

let (tx, rx) = oneshot::channel::<i32>();

(async { tx.send(5).unwrap() }).run_in_background();

assert_eq!(rx.await, Ok(5));

Important traits for InterleavePending<Fut>

impl<Fut: Future> Future for InterleavePending<Fut> type Output = Fut::Output;

fn interleave_pending(self) -> InterleavePending<Self> where
    Self: Sized, 

Introduces an extra Poll::Pending in between each call to poll.

Examples

use futures::task::Poll;
use futures::future::{self, Future};
use futures_test::task::noop_context;
use futures_test::future::FutureTestExt;
use futures::pin_mut;

let future = future::ready(1).interleave_pending();
pin_mut!(future);

let mut cx = noop_context();

assert_eq!(future.as_mut().poll(&mut cx), Poll::Pending);
assert_eq!(future.as_mut().poll(&mut cx), Poll::Ready(1));

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Implementors

impl<Fut> FutureTestExt for Fut where
    Fut: Future, 

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