futures_test/future/
mod.rs

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1//! Additional combinators for testing futures.
2
3mod pending_once;
4pub use self::pending_once::PendingOnce;
5
6use futures_core::future::Future;
7use std::thread;
8
9pub use crate::assert_unmoved::AssertUnmoved;
10pub use crate::interleave_pending::InterleavePending;
11
12/// Additional combinators for testing futures.
13pub trait FutureTestExt: Future {
14    /// Asserts that the given is not moved after being polled.
15    ///
16    /// A check for movement is performed each time the future is polled
17    /// and when `Drop` is called.
18    ///
19    /// Aside from keeping track of the location at which the future was first
20    /// polled and providing assertions, this future adds no runtime behavior
21    /// and simply delegates to the child future.
22    fn assert_unmoved(self) -> AssertUnmoved<Self>
23    where
24        Self: Sized,
25    {
26        AssertUnmoved::new(self)
27    }
28
29    /// Introduces one [`Poll::Pending`](futures_core::task::Poll::Pending)
30    /// before polling the given future.
31    ///
32    /// # Examples
33    ///
34    /// ```
35    /// use futures::task::Poll;
36    /// use futures::future::FutureExt;
37    /// use futures_test::task::noop_context;
38    /// use futures_test::future::FutureTestExt;
39    /// use futures::pin_mut;
40    ///
41    /// let future = (async { 5 }).pending_once();
42    /// pin_mut!(future);
43    ///
44    /// let mut cx = noop_context();
45    ///
46    /// assert_eq!(future.poll_unpin(&mut cx), Poll::Pending);
47    /// assert_eq!(future.poll_unpin(&mut cx), Poll::Ready(5));
48    /// ```
49    fn pending_once(self) -> PendingOnce<Self>
50    where
51        Self: Sized,
52    {
53        PendingOnce::new(self)
54    }
55
56    /// Runs this future on a dedicated executor running in a background thread.
57    ///
58    /// # Examples
59    ///
60    /// ```
61    /// # futures::executor::block_on(async {
62    /// use futures::channel::oneshot;
63    /// use futures_test::future::FutureTestExt;
64    ///
65    /// let (tx, rx) = oneshot::channel::<i32>();
66    ///
67    /// (async { tx.send(5).unwrap() }).run_in_background();
68    ///
69    /// assert_eq!(rx.await, Ok(5));
70    /// # });
71    /// # std::thread::sleep(std::time::Duration::from_millis(500)); // wait for background threads closed: https://github.com/rust-lang/miri/issues/1371
72    /// ```
73    fn run_in_background(self)
74    where
75        Self: Sized + Send + 'static,
76        Self::Output: Send,
77    {
78        thread::spawn(|| futures_executor::block_on(self));
79    }
80
81    /// Introduces an extra [`Poll::Pending`](futures_core::task::Poll::Pending)
82    /// in between each call to poll.
83    ///
84    /// # Examples
85    ///
86    /// ```
87    /// use futures::task::Poll;
88    /// use futures::future::{self, Future};
89    /// use futures_test::task::noop_context;
90    /// use futures_test::future::FutureTestExt;
91    /// use futures::pin_mut;
92    ///
93    /// let future = future::ready(1).interleave_pending();
94    /// pin_mut!(future);
95    ///
96    /// let mut cx = noop_context();
97    ///
98    /// assert_eq!(future.as_mut().poll(&mut cx), Poll::Pending);
99    /// assert_eq!(future.as_mut().poll(&mut cx), Poll::Ready(1));
100    /// ```
101    fn interleave_pending(self) -> InterleavePending<Self>
102    where
103        Self: Sized,
104    {
105        InterleavePending::new(self)
106    }
107}
108
109impl<Fut> FutureTestExt for Fut where Fut: Future {}
futures_test/future/mod.rs

futures_test/future/
mod.rs
