futures_test/io/read/
mod.rs

1//! Additional combinators for testing async readers.
2
3use futures_io::AsyncRead;
4
5pub use super::limited::Limited;
6pub use crate::interleave_pending::InterleavePending;
7
8/// Additional combinators for testing async readers.
9pub trait AsyncReadTestExt: AsyncRead {
10    /// Introduces an extra [`Poll::Pending`](futures_core::task::Poll::Pending)
11    /// in between each read of the reader.
12    ///
13    /// # Examples
14    ///
15    /// ```
16    /// use futures::task::Poll;
17    /// use futures::io::AsyncRead;
18    /// use futures_test::task::noop_context;
19    /// use futures_test::io::AsyncReadTestExt;
20    /// use futures::pin_mut;
21    ///
22    /// let reader = std::io::Cursor::new(&[1, 2, 3]).interleave_pending();
23    /// pin_mut!(reader);
24    ///
25    /// let mut cx = noop_context();
26    ///
27    /// let mut buf = [0, 0];
28    ///
29    /// assert_eq!(reader.as_mut().poll_read(&mut cx, &mut buf[..])?, Poll::Pending);
30    /// assert_eq!(reader.as_mut().poll_read(&mut cx, &mut buf[..])?, Poll::Ready(2));
31    /// assert_eq!(buf, [1, 2]);
32    /// assert_eq!(reader.as_mut().poll_read(&mut cx, &mut buf[..])?, Poll::Pending);
33    /// assert_eq!(reader.as_mut().poll_read(&mut cx, &mut buf[..])?, Poll::Ready(1));
34    /// assert_eq!(buf, [3, 2]);
35    /// assert_eq!(reader.as_mut().poll_read(&mut cx, &mut buf[..])?, Poll::Pending);
36    /// assert_eq!(reader.as_mut().poll_read(&mut cx, &mut buf[..])?, Poll::Ready(0));
37    ///
38    /// # Ok::<(), std::io::Error>(())
39    /// ```
40    ///
41    /// ## `AsyncBufRead`
42    ///
43    /// The returned reader will also implement `AsyncBufRead` if the underlying reader does.
44    ///
45    /// ```
46    /// use futures::task::Poll;
47    /// use futures::io::AsyncBufRead;
48    /// use futures_test::task::noop_context;
49    /// use futures_test::io::AsyncReadTestExt;
50    /// use futures::pin_mut;
51    ///
52    /// let reader = std::io::Cursor::new(&[1, 2, 3]).interleave_pending();
53    /// pin_mut!(reader);
54    ///
55    /// let mut cx = noop_context();
56    ///
57    /// assert_eq!(reader.as_mut().poll_fill_buf(&mut cx)?, Poll::Pending);
58    /// assert_eq!(reader.as_mut().poll_fill_buf(&mut cx)?, Poll::Ready(&[1, 2, 3][..]));
59    /// reader.as_mut().consume(2);
60    /// assert_eq!(reader.as_mut().poll_fill_buf(&mut cx)?, Poll::Pending);
61    /// assert_eq!(reader.as_mut().poll_fill_buf(&mut cx)?, Poll::Ready(&[3][..]));
62    /// reader.as_mut().consume(1);
63    /// assert_eq!(reader.as_mut().poll_fill_buf(&mut cx)?, Poll::Pending);
64    /// assert_eq!(reader.as_mut().poll_fill_buf(&mut cx)?, Poll::Ready(&[][..]));
65    ///
66    /// # Ok::<(), std::io::Error>(())
67    /// ```
68    fn interleave_pending(self) -> InterleavePending<Self>
69    where
70        Self: Sized,
71    {
72        InterleavePending::new(self)
73    }
74
75    /// Limit the number of bytes allowed to be read on each call to `poll_read`.
76    ///
77    /// # Examples
78    ///
79    /// ```
80    /// use futures::task::Poll;
81    /// use futures::io::AsyncRead;
82    /// use futures_test::task::noop_context;
83    /// use futures_test::io::AsyncReadTestExt;
84    /// use futures::pin_mut;
85    ///
86    /// let reader = std::io::Cursor::new(&[1, 2, 3, 4, 5]).limited(2);
87    /// pin_mut!(reader);
88    ///
89    /// let mut cx = noop_context();
90    ///
91    /// let mut buf = [0; 10];
92    ///
93    /// assert_eq!(reader.as_mut().poll_read(&mut cx, &mut buf)?, Poll::Ready(2));
94    /// assert_eq!(&buf[..2], &[1, 2]);
95    /// assert_eq!(reader.as_mut().poll_read(&mut cx, &mut buf)?, Poll::Ready(2));
96    /// assert_eq!(&buf[..2], &[3, 4]);
97    /// assert_eq!(reader.as_mut().poll_read(&mut cx, &mut buf)?, Poll::Ready(1));
98    /// assert_eq!(&buf[..1], &[5]);
99    ///
100    /// # Ok::<(), std::io::Error>(())
101    /// ```
102    fn limited(self, limit: usize) -> Limited<Self>
103    where
104        Self: Sized,
105    {
106        Limited::new(self, limit)
107    }
108}
109
110impl<R> AsyncReadTestExt for R where R: AsyncRead {}
futures_test/io/read/mod.rs

futures_test/io/read/
mod.rs
