futures_test/future/
mod.rs

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 core::pin::pin;
36    ///
37    /// use futures::task::Poll;
38    /// use futures::future::FutureExt;
39    /// use futures_test::task::noop_context;
40    /// use futures_test::future::FutureTestExt;
41    ///
42    /// let future = (async { 5 }).pending_once();
43    /// let mut future = pin!(future);
44    ///
45    /// let mut cx = noop_context();
46    ///
47    /// assert_eq!(future.poll_unpin(&mut cx), Poll::Pending);
48    /// assert_eq!(future.poll_unpin(&mut cx), Poll::Ready(5));
49    /// ```
50    fn pending_once(self) -> PendingOnce<Self>
51    where
52        Self: Sized,
53    {
54        PendingOnce::new(self)
55    }
56
57    /// Runs this future on a dedicated executor running in a background thread.
58    ///
59    /// # Examples
60    ///
61    /// ```
62    /// # futures::executor::block_on(async {
63    /// use futures::channel::oneshot;
64    /// use futures_test::future::FutureTestExt;
65    ///
66    /// let (tx, rx) = oneshot::channel::<i32>();
67    ///
68    /// (async { tx.send(5).unwrap() }).run_in_background();
69    ///
70    /// assert_eq!(rx.await, Ok(5));
71    /// # });
72    /// # std::thread::sleep(std::time::Duration::from_millis(500)); // wait for background threads closed: https://github.com/rust-lang/miri/issues/1371
73    /// ```
74    fn run_in_background(self)
75    where
76        Self: Sized + Send + 'static,
77        Self::Output: Send,
78    {
79        thread::spawn(|| futures_executor::block_on(self));
80    }
81
82    /// Introduces an extra [`Poll::Pending`](futures_core::task::Poll::Pending)
83    /// in between each call to poll.
84    ///
85    /// # Examples
86    ///
87    /// ```
88    /// use core::pin::pin;
89    ///
90    /// use futures::task::Poll;
91    /// use futures::future::{self, Future};
92    /// use futures_test::task::noop_context;
93    /// use futures_test::future::FutureTestExt;
94    ///
95    /// let future = future::ready(1).interleave_pending();
96    /// let mut future = pin!(future);
97    ///
98    /// let mut cx = noop_context();
99    ///
100    /// assert_eq!(future.as_mut().poll(&mut cx), Poll::Pending);
101    /// assert_eq!(future.as_mut().poll(&mut cx), Poll::Ready(1));
102    /// ```
103    fn interleave_pending(self) -> InterleavePending<Self>
104    where
105        Self: Sized,
106    {
107        InterleavePending::new(self)
108    }
109}
110
111impl<Fut> FutureTestExt for Fut where Fut: Future {}
futures_test/future/mod.rs

futures_test/future/
mod.rs
