Initial vendor packages

Signed-off-by: Valentin Popov <valentin@popov.link>

1 files changed, 2095 insertions, 0 deletions

diff --git a/vendor/flume/tests/mpsc.rs b/vendor/flume/tests/mpsc.rs
new file mode 100644
index 0000000..213b9d8
--- /dev/null
+++ b/vendor/flume/tests/mpsc.rs
@@ -0,0 +1,2095 @@
+//! Tests copied from `std::sync::mpsc`.
+//!
+//! This is a copy of tests for the `std::sync::mpsc` channels from the standard library, but
+//! modified to work with `crossbeam-channel` instead.
+//!
+//! Minor tweaks were needed to make the tests compile:
+//!
+//! - Replace `box` syntax with `Box::new`.
+//! - Replace all uses of `Select` with `select!`.
+//! - Change the imports.
+//! - Join all spawned threads.
+//! - Removed assertion from oneshot_multi_thread_send_close_stress tests.
+//!
+//! Source:
+//!   - https://github.com/rust-lang/rust/tree/master/src/libstd/sync/mpsc
+//!
+//! Copyright & License:
+//!   - Copyright 2013-2014 The Rust Project Developers
+//!   - Apache License, Version 2.0 or MIT license, at your option
+//!   - https://github.com/rust-lang/rust/blob/master/COPYRIGHT
+//!   - https://www.rust-lang.org/en-US/legal.html
+
+#[macro_use]
+extern crate crossbeam_channel as cc;
+
+use std::sync::mpsc::{RecvError, RecvTimeoutError, TryRecvError};
+use std::sync::mpsc::{SendError, TrySendError};
+use std::thread::JoinHandle;
+use std::time::Duration;
+
+pub struct Sender<T> {
+    pub inner: cc::Sender<T>,
+}
+
+impl<T> Sender<T> {
+    pub fn send(&self, t: T) -> Result<(), SendError<T>> {
+        self.inner.send(t).map_err(|cc::SendError(m)| SendError(m))
+    }
+}
+
+impl<T> Clone for Sender<T> {
+    fn clone(&self) -> Sender<T> {
+        Sender {
+            inner: self.inner.clone(),
+        }
+    }
+}
+
+pub struct SyncSender<T> {
+    pub inner: cc::Sender<T>,
+}
+
+impl<T> SyncSender<T> {
+    pub fn send(&self, t: T) -> Result<(), SendError<T>> {
+        self.inner.send(t).map_err(|cc::SendError(m)| SendError(m))
+    }
+
+    pub fn try_send(&self, t: T) -> Result<(), TrySendError<T>> {
+        self.inner.try_send(t).map_err(|err| match err {
+            cc::TrySendError::Full(m) => TrySendError::Full(m),
+            cc::TrySendError::Disconnected(m) => TrySendError::Disconnected(m),
+        })
+    }
+}
+
+impl<T> Clone for SyncSender<T> {
+    fn clone(&self) -> SyncSender<T> {
+        SyncSender {
+            inner: self.inner.clone(),
+        }
+    }
+}
+
+pub struct Receiver<T> {
+    pub inner: cc::Receiver<T>,
+}
+
+impl<T> Receiver<T> {
+    pub fn try_recv(&self) -> Result<T, TryRecvError> {
+        self.inner.try_recv().map_err(|err| match err {
+            cc::TryRecvError::Empty => TryRecvError::Empty,
+            cc::TryRecvError::Disconnected => TryRecvError::Disconnected,
+        })
+    }
+
+    pub fn recv(&self) -> Result<T, RecvError> {
+        self.inner.recv().map_err(|_| RecvError)
+    }
+
+    pub fn recv_timeout(&self, timeout: Duration) -> Result<T, RecvTimeoutError> {
+        self.inner.recv_timeout(timeout).map_err(|err| match err {
+            cc::RecvTimeoutError::Timeout => RecvTimeoutError::Timeout,
+            cc::RecvTimeoutError::Disconnected => RecvTimeoutError::Disconnected,
+        })
+    }
+
+    pub fn iter(&self) -> Iter<T> {
+        Iter { inner: self }
+    }
+
+    pub fn try_iter(&self) -> TryIter<T> {
+        TryIter { inner: self }
+    }
+}
+
+impl<'a, T> IntoIterator for &'a Receiver<T> {
+    type Item = T;
+    type IntoIter = Iter<'a, T>;
+
+    fn into_iter(self) -> Iter<'a, T> {
+        self.iter()
+    }
+}
+
+impl<T> IntoIterator for Receiver<T> {
+    type Item = T;
+    type IntoIter = IntoIter<T>;
+
+    fn into_iter(self) -> IntoIter<T> {
+        IntoIter { inner: self }
+    }
+}
+
+pub struct TryIter<'a, T: 'a> {
+    inner: &'a Receiver<T>,
+}
+
+impl<'a, T> Iterator for TryIter<'a, T> {
+    type Item = T;
+
+    fn next(&mut self) -> Option<T> {
+        self.inner.try_recv().ok()
+    }
+}
+
+pub struct Iter<'a, T: 'a> {
+    inner: &'a Receiver<T>,
+}
+
+impl<'a, T> Iterator for Iter<'a, T> {
+    type Item = T;
+
+    fn next(&mut self) -> Option<T> {
+        self.inner.recv().ok()
+    }
+}
+
+pub struct IntoIter<T> {
+    inner: Receiver<T>,
+}
+
+impl<T> Iterator for IntoIter<T> {
+    type Item = T;
+
+    fn next(&mut self) -> Option<T> {
+        self.inner.recv().ok()
+    }
+}
+
+pub fn channel<T>() -> (Sender<T>, Receiver<T>) {
+    let (s, r) = cc::unbounded();
+    let s = Sender { inner: s };
+    let r = Receiver { inner: r };
+    (s, r)
+}
+
+pub fn sync_channel<T>(bound: usize) -> (SyncSender<T>, Receiver<T>) {
+    let (s, r) = cc::bounded(bound);
+    let s = SyncSender { inner: s };
+    let r = Receiver { inner: r };
+    (s, r)
+}
+
+macro_rules! select {
+    (
+        $($name:pat = $rx:ident.$meth:ident() => $code:expr),+
+    ) => ({
+        crossbeam_channel_internal! {
+            $(
+                recv(($rx).inner) -> res => {
+                    let $name = res.map_err(|_| ::std::sync::mpsc::RecvError);
+                    $code
+                }
+            )+
+        }
+    })
+}
+
+// Source: https://github.com/rust-lang/rust/blob/master/src/libstd/sync/mpsc/mod.rs
+mod channel_tests {
+    use super::*;
+
+    use std::env;
+    use std::thread;
+    use std::time::{Duration, Instant};
+
+    pub fn stress_factor() -> usize {
+        match env::var("RUST_TEST_STRESS") {
+            Ok(val) => val.parse().unwrap(),
+            Err(..) => 1,
+        }
+    }
+
+    #[test]
+    fn smoke() {
+        let (tx, rx) = channel::<i32>();
+        tx.send(1).unwrap();
+        assert_eq!(rx.recv().unwrap(), 1);
+    }
+
+    #[test]
+    fn drop_full() {
+        let (tx, _rx) = channel::<Box<isize>>();
+        tx.send(Box::new(1)).unwrap();
+    }
+
+    #[test]
+    fn drop_full_shared() {
+        let (tx, _rx) = channel::<Box<isize>>();
+        drop(tx.clone());
+        drop(tx.clone());
+        tx.send(Box::new(1)).unwrap();
+    }
+
+    #[test]
+    fn smoke_shared() {
+        let (tx, rx) = channel::<i32>();
+        tx.send(1).unwrap();
+        assert_eq!(rx.recv().unwrap(), 1);
+        let tx = tx.clone();
+        tx.send(1).unwrap();
+        assert_eq!(rx.recv().unwrap(), 1);
+    }
+
+    #[test]
+    fn smoke_threads() {
+        let (tx, rx) = channel::<i32>();
+        let t = thread::spawn(move || {
+            tx.send(1).unwrap();
+        });
+        assert_eq!(rx.recv().unwrap(), 1);
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn smoke_port_gone() {
+        let (tx, rx) = channel::<i32>();
+        drop(rx);
+        assert!(tx.send(1).is_err());
+    }
+
+    #[test]
+    fn smoke_shared_port_gone() {
+        let (tx, rx) = channel::<i32>();
+        drop(rx);
+        assert!(tx.send(1).is_err())
+    }
+
+    #[test]
+    fn smoke_shared_port_gone2() {
+        let (tx, rx) = channel::<i32>();
+        drop(rx);
+        let tx2 = tx.clone();
+        drop(tx);
+        assert!(tx2.send(1).is_err());
+    }
+
+    #[test]
+    fn port_gone_concurrent() {
+        let (tx, rx) = channel::<i32>();
+        let t = thread::spawn(move || {
+            rx.recv().unwrap();
+        });
+        while tx.send(1).is_ok() {}
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn port_gone_concurrent_shared() {
+        let (tx, rx) = channel::<i32>();
+        let tx2 = tx.clone();
+        let t = thread::spawn(move || {
+            rx.recv().unwrap();
+        });
+        while tx.send(1).is_ok() && tx2.send(1).is_ok() {}
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn smoke_chan_gone() {
+        let (tx, rx) = channel::<i32>();
+        drop(tx);
+        assert!(rx.recv().is_err());
+    }
+
+    #[test]
+    fn smoke_chan_gone_shared() {
+        let (tx, rx) = channel::<()>();
+        let tx2 = tx.clone();
+        drop(tx);
+        drop(tx2);
+        assert!(rx.recv().is_err());
+    }
+
+    #[test]
+    fn chan_gone_concurrent() {
+        let (tx, rx) = channel::<i32>();
+        let t = thread::spawn(move || {
+            tx.send(1).unwrap();
+            tx.send(1).unwrap();
+        });
+        while rx.recv().is_ok() {}
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn stress() {
+        let (tx, rx) = channel::<i32>();
+        let t = thread::spawn(move || {
+            for _ in 0..10000 {
+                tx.send(1).unwrap();
+            }
+        });
+        for _ in 0..10000 {
+            assert_eq!(rx.recv().unwrap(), 1);
+        }
+        t.join().ok().unwrap();
+    }
+
+    #[test]
+    fn stress_shared() {
+        const AMT: u32 = 10000;
+        const NTHREADS: u32 = 8;
+        let (tx, rx) = channel::<i32>();
+
+        let t = thread::spawn(move || {
+            for _ in 0..AMT * NTHREADS {
+                assert_eq!(rx.recv().unwrap(), 1);
+            }
+            match rx.try_recv() {
+                Ok(..) => panic!(),
+                _ => {}
+            }
+        });
+
+        let mut ts = Vec::with_capacity(NTHREADS as usize);
+        for _ in 0..NTHREADS {
+            let tx = tx.clone();
+            let t = thread::spawn(move || {
+                for _ in 0..AMT {
+                    tx.send(1).unwrap();
+                }
+            });
+            ts.push(t);
+        }
+        drop(tx);
+        t.join().ok().unwrap();
+        for t in ts {
+            t.join().unwrap();
+        }
+    }
+
+    #[test]
+    fn send_from_outside_runtime() {
+        let (tx1, rx1) = channel::<()>();
+        let (tx2, rx2) = channel::<i32>();
+        let t1 = thread::spawn(move || {
+            tx1.send(()).unwrap();
+            for _ in 0..40 {
+                assert_eq!(rx2.recv().unwrap(), 1);
+            }
+        });
+        rx1.recv().unwrap();
+        let t2 = thread::spawn(move || {
+            for _ in 0..40 {
+                tx2.send(1).unwrap();
+            }
+        });
+        t1.join().ok().unwrap();
+        t2.join().ok().unwrap();
+    }
+
+    #[test]
+    fn recv_from_outside_runtime() {
+        let (tx, rx) = channel::<i32>();
+        let t = thread::spawn(move || {
+            for _ in 0..40 {
+                assert_eq!(rx.recv().unwrap(), 1);
+            }
+        });
+        for _ in 0..40 {
+            tx.send(1).unwrap();
+        }
+        t.join().ok().unwrap();
+    }
+
+    #[test]
+    fn no_runtime() {
+        let (tx1, rx1) = channel::<i32>();
+        let (tx2, rx2) = channel::<i32>();
+        let t1 = thread::spawn(move || {
+            assert_eq!(rx1.recv().unwrap(), 1);
+            tx2.send(2).unwrap();
+        });
+        let t2 = thread::spawn(move || {
+            tx1.send(1).unwrap();
+            assert_eq!(rx2.recv().unwrap(), 2);
+        });
+        t1.join().ok().unwrap();
+        t2.join().ok().unwrap();
+    }
+
+    #[test]
+    fn oneshot_single_thread_close_port_first() {
+        // Simple test of closing without sending
+        let (_tx, rx) = channel::<i32>();
+        drop(rx);
+    }
+
+    #[test]
+    fn oneshot_single_thread_close_chan_first() {
+        // Simple test of closing without sending
+        let (tx, _rx) = channel::<i32>();
+        drop(tx);
+    }
+
+    #[test]
+    fn oneshot_single_thread_send_port_close() {
+        // Testing that the sender cleans up the payload if receiver is closed
+        let (tx, rx) = channel::<Box<i32>>();
+        drop(rx);
+        assert!(tx.send(Box::new(0)).is_err());
+    }
+
+    #[test]
+    fn oneshot_single_thread_recv_chan_close() {
+        let (tx, rx) = channel::<i32>();
+        drop(tx);
+        assert_eq!(rx.recv(), Err(RecvError));
+    }
+
+    #[test]
+    fn oneshot_single_thread_send_then_recv() {
+        let (tx, rx) = channel::<Box<i32>>();
+        tx.send(Box::new(10)).unwrap();
+        assert!(*rx.recv().unwrap() == 10);
+    }
+
+    #[test]
+    fn oneshot_single_thread_try_send_open() {
+        let (tx, rx) = channel::<i32>();
+        assert!(tx.send(10).is_ok());
+        assert!(rx.recv().unwrap() == 10);
+    }
+
+    #[test]
+    fn oneshot_single_thread_try_send_closed() {
+        let (tx, rx) = channel::<i32>();
+        drop(rx);
+        assert!(tx.send(10).is_err());
+    }
+
+    #[test]
+    fn oneshot_single_thread_try_recv_open() {
+        let (tx, rx) = channel::<i32>();
+        tx.send(10).unwrap();
+        assert!(rx.recv() == Ok(10));
+    }
+
+    #[test]
+    fn oneshot_single_thread_try_recv_closed() {
+        let (tx, rx) = channel::<i32>();
+        drop(tx);
+        assert!(rx.recv().is_err());
+    }
+
+    #[test]
+    fn oneshot_single_thread_peek_data() {
+        let (tx, rx) = channel::<i32>();
+        assert_eq!(rx.try_recv(), Err(TryRecvError::Empty));
+        tx.send(10).unwrap();
+        assert_eq!(rx.try_recv(), Ok(10));
+    }
+
+    #[test]
+    fn oneshot_single_thread_peek_close() {
+        let (tx, rx) = channel::<i32>();
+        drop(tx);
+        assert_eq!(rx.try_recv(), Err(TryRecvError::Disconnected));
+        assert_eq!(rx.try_recv(), Err(TryRecvError::Disconnected));
+    }
+
+    #[test]
+    fn oneshot_single_thread_peek_open() {
+        let (_tx, rx) = channel::<i32>();
+        assert_eq!(rx.try_recv(), Err(TryRecvError::Empty));
+    }
+
+    #[test]
+    fn oneshot_multi_task_recv_then_send() {
+        let (tx, rx) = channel::<Box<i32>>();
+        let t = thread::spawn(move || {
+            assert!(*rx.recv().unwrap() == 10);
+        });
+
+        tx.send(Box::new(10)).unwrap();
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn oneshot_multi_task_recv_then_close() {
+        let (tx, rx) = channel::<Box<i32>>();
+        let t = thread::spawn(move || {
+            drop(tx);
+        });
+        thread::spawn(move || {
+            assert_eq!(rx.recv(), Err(RecvError));
+        })
+        .join()
+        .unwrap();
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn oneshot_multi_thread_close_stress() {
+        let stress_factor = stress_factor();
+        let mut ts = Vec::with_capacity(stress_factor);
+        for _ in 0..stress_factor {
+            let (tx, rx) = channel::<i32>();
+            let t = thread::spawn(move || {
+                drop(rx);
+            });
+            ts.push(t);
+            drop(tx);
+        }
+        for t in ts {
+            t.join().unwrap();
+        }
+    }
+
+    #[test]
+    fn oneshot_multi_thread_send_close_stress() {
+        let stress_factor = stress_factor();
+        let mut ts = Vec::with_capacity(2 * stress_factor);
+        for _ in 0..stress_factor {
+            let (tx, rx) = channel::<i32>();
+            let t = thread::spawn(move || {
+                drop(rx);
+            });
+            ts.push(t);
+            thread::spawn(move || {
+                let _ = tx.send(1);
+            })
+            .join()
+            .unwrap();
+        }
+        for t in ts {
+            t.join().unwrap();
+        }
+    }
+
+    #[test]
+    fn oneshot_multi_thread_recv_close_stress() {
+        let stress_factor = stress_factor();
+        let mut ts = Vec::with_capacity(2 * stress_factor);
+        for _ in 0..stress_factor {
+            let (tx, rx) = channel::<i32>();
+            let t = thread::spawn(move || {
+                thread::spawn(move || {
+                    assert_eq!(rx.recv(), Err(RecvError));
+                })
+                .join()
+                .unwrap();
+            });
+            ts.push(t);
+            let t2 = thread::spawn(move || {
+                let t = thread::spawn(move || {
+                    drop(tx);
+                });
+                t.join().unwrap();
+            });
+            ts.push(t2);
+        }
+        for t in ts {
+            t.join().unwrap();
+        }
+    }
+
+    #[test]
+    fn oneshot_multi_thread_send_recv_stress() {
+        let stress_factor = stress_factor();
+        let mut ts = Vec::with_capacity(stress_factor);
+        for _ in 0..stress_factor {
+            let (tx, rx) = channel::<Box<isize>>();
+            let t = thread::spawn(move || {
+                tx.send(Box::new(10)).unwrap();
+            });
+            ts.push(t);
+            assert!(*rx.recv().unwrap() == 10);
+        }
+        for t in ts {
+            t.join().unwrap();
+        }
+    }
+
+    #[test]
+    fn stream_send_recv_stress() {
+        let stress_factor = stress_factor();
+        let mut ts = Vec::with_capacity(2 * stress_factor);
+        for _ in 0..stress_factor {
+            let (tx, rx) = channel();
+
+            if let Some(t) = send(tx, 0) {
+                ts.push(t);
+            }
+            if let Some(t2) = recv(rx, 0) {
+                ts.push(t2);
+            }
+
+            fn send(tx: Sender<Box<i32>>, i: i32) -> Option<JoinHandle<()>> {
+                if i == 10 {
+                    return None;
+                }
+
+                Some(thread::spawn(move || {
+                    tx.send(Box::new(i)).unwrap();
+                    send(tx, i + 1);
+                }))
+            }
+
+            fn recv(rx: Receiver<Box<i32>>, i: i32) -> Option<JoinHandle<()>> {
+                if i == 10 {
+                    return None;
+                }
+
+                Some(thread::spawn(move || {
+                    assert!(*rx.recv().unwrap() == i);
+                    recv(rx, i + 1);
+                }))
+            }
+        }
+        for t in ts {
+            t.join().unwrap();
+        }
+    }
+
+    #[test]
+    fn oneshot_single_thread_recv_timeout() {
+        let (tx, rx) = channel();
+        tx.send(()).unwrap();
+        assert_eq!(rx.recv_timeout(Duration::from_millis(1)), Ok(()));
+        assert_eq!(
+            rx.recv_timeout(Duration::from_millis(1)),
+            Err(RecvTimeoutError::Timeout)
+        );
+        tx.send(()).unwrap();
+        assert_eq!(rx.recv_timeout(Duration::from_millis(1)), Ok(()));
+    }
+
+    #[test]
+    fn stress_recv_timeout_two_threads() {
+        let (tx, rx) = channel();
+        let stress = stress_factor() + 100;
+        let timeout = Duration::from_millis(100);
+
+        let t = thread::spawn(move || {
+            for i in 0..stress {
+                if i % 2 == 0 {
+                    thread::sleep(timeout * 2);
+                }
+                tx.send(1usize).unwrap();
+            }
+        });
+
+        let mut recv_count = 0;
+        loop {
+            match rx.recv_timeout(timeout) {
+                Ok(n) => {
+                    assert_eq!(n, 1usize);
+                    recv_count += 1;
+                }
+                Err(RecvTimeoutError::Timeout) => continue,
+                Err(RecvTimeoutError::Disconnected) => break,
+            }
+        }
+
+        assert_eq!(recv_count, stress);
+        t.join().unwrap()
+    }
+
+    #[test]
+    fn recv_timeout_upgrade() {
+        let (tx, rx) = channel::<()>();
+        let timeout = Duration::from_millis(1);
+        let _tx_clone = tx.clone();
+
+        let start = Instant::now();
+        assert_eq!(rx.recv_timeout(timeout), Err(RecvTimeoutError::Timeout));
+        assert!(Instant::now() >= start + timeout);
+    }
+
+    #[test]
+    fn stress_recv_timeout_shared() {
+        let (tx, rx) = channel();
+        let stress = stress_factor() + 100;
+
+        let mut ts = Vec::with_capacity(stress);
+        for i in 0..stress {
+            let tx = tx.clone();
+            let t = thread::spawn(move || {
+                thread::sleep(Duration::from_millis(i as u64 * 10));
+                tx.send(1usize).unwrap();
+            });
+            ts.push(t);
+        }
+
+        drop(tx);
+
+        let mut recv_count = 0;
+        loop {
+            match rx.recv_timeout(Duration::from_millis(10)) {
+                Ok(n) => {
+                    assert_eq!(n, 1usize);
+                    recv_count += 1;
+                }
+                Err(RecvTimeoutError::Timeout) => continue,
+                Err(RecvTimeoutError::Disconnected) => break,
+            }
+        }
+
+        assert_eq!(recv_count, stress);
+        for t in ts {
+            t.join().unwrap();
+        }
+    }
+
+    #[test]
+    fn recv_a_lot() {
+        // Regression test that we don't run out of stack in scheduler context
+        let (tx, rx) = channel();
+        for _ in 0..10000 {
+            tx.send(()).unwrap();
+        }
+        for _ in 0..10000 {
+            rx.recv().unwrap();
+        }
+    }
+
+    #[test]
+    fn shared_recv_timeout() {
+        let (tx, rx) = channel();
+        let total = 5;
+        let mut ts = Vec::with_capacity(total);
+        for _ in 0..total {
+            let tx = tx.clone();
+            let t = thread::spawn(move || {
+                tx.send(()).unwrap();
+            });
+            ts.push(t);
+        }
+
+        for _ in 0..total {
+            rx.recv().unwrap();
+        }
+
+        assert_eq!(
+            rx.recv_timeout(Duration::from_millis(1)),
+            Err(RecvTimeoutError::Timeout)
+        );
+        tx.send(()).unwrap();
+        assert_eq!(rx.recv_timeout(Duration::from_millis(1)), Ok(()));
+        for t in ts {
+            t.join().unwrap();
+        }
+    }
+
+    #[test]
+    fn shared_chan_stress() {
+        let (tx, rx) = channel();
+        let total = stress_factor() + 100;
+        let mut ts = Vec::with_capacity(total);
+        for _ in 0..total {
+            let tx = tx.clone();
+            let t = thread::spawn(move || {
+                tx.send(()).unwrap();
+            });
+            ts.push(t);
+        }
+
+        for _ in 0..total {
+            rx.recv().unwrap();
+        }
+        for t in ts {
+            t.join().unwrap();
+        }
+    }
+
+    #[test]
+    fn test_nested_recv_iter() {
+        let (tx, rx) = channel::<i32>();
+        let (total_tx, total_rx) = channel::<i32>();
+
+        let t = thread::spawn(move || {
+            let mut acc = 0;
+            for x in rx.iter() {
+                acc += x;
+            }
+            total_tx.send(acc).unwrap();
+        });
+
+        tx.send(3).unwrap();
+        tx.send(1).unwrap();
+        tx.send(2).unwrap();
+        drop(tx);
+        assert_eq!(total_rx.recv().unwrap(), 6);
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn test_recv_iter_break() {
+        let (tx, rx) = channel::<i32>();
+        let (count_tx, count_rx) = channel();
+
+        let t = thread::spawn(move || {
+            let mut count = 0;
+            for x in rx.iter() {
+                if count >= 3 {
+                    break;
+                } else {
+                    count += x;
+                }
+            }
+            count_tx.send(count).unwrap();
+        });
+
+        tx.send(2).unwrap();
+        tx.send(2).unwrap();
+        tx.send(2).unwrap();
+        let _ = tx.send(2);
+        drop(tx);
+        assert_eq!(count_rx.recv().unwrap(), 4);
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn test_recv_try_iter() {
+        let (request_tx, request_rx) = channel();
+        let (response_tx, response_rx) = channel();
+
+        // Request `x`s until we have `6`.
+        let t = thread::spawn(move || {
+            let mut count = 0;
+            loop {
+                for x in response_rx.try_iter() {
+                    count += x;
+                    if count == 6 {
+                        return count;
+                    }
+                }
+                request_tx.send(()).unwrap();
+            }
+        });
+
+        for _ in request_rx.iter() {
+            if response_tx.send(2).is_err() {
+                break;
+            }
+        }
+
+        assert_eq!(t.join().unwrap(), 6);
+    }
+
+    #[test]
+    fn test_recv_into_iter_owned() {
+        let mut iter = {
+            let (tx, rx) = channel::<i32>();
+            tx.send(1).unwrap();
+            tx.send(2).unwrap();
+
+            rx.into_iter()
+        };
+        assert_eq!(iter.next().unwrap(), 1);
+        assert_eq!(iter.next().unwrap(), 2);
+        assert_eq!(iter.next().is_none(), true);
+    }
+
+    #[test]
+    fn test_recv_into_iter_borrowed() {
+        let (tx, rx) = channel::<i32>();
+        tx.send(1).unwrap();
+        tx.send(2).unwrap();
+        drop(tx);
+        let mut iter = (&rx).into_iter();
+        assert_eq!(iter.next().unwrap(), 1);
+        assert_eq!(iter.next().unwrap(), 2);
+        assert_eq!(iter.next().is_none(), true);
+    }
+
+    #[test]
+    fn try_recv_states() {
+        let (tx1, rx1) = channel::<i32>();
+        let (tx2, rx2) = channel::<()>();
+        let (tx3, rx3) = channel::<()>();
+        let t = thread::spawn(move || {
+            rx2.recv().unwrap();
+            tx1.send(1).unwrap();
+            tx3.send(()).unwrap();
+            rx2.recv().unwrap();
+            drop(tx1);
+            tx3.send(()).unwrap();
+        });
+
+        assert_eq!(rx1.try_recv(), Err(TryRecvError::Empty));
+        tx2.send(()).unwrap();
+        rx3.recv().unwrap();
+        assert_eq!(rx1.try_recv(), Ok(1));
+        assert_eq!(rx1.try_recv(), Err(TryRecvError::Empty));
+        tx2.send(()).unwrap();
+        rx3.recv().unwrap();
+        assert_eq!(rx1.try_recv(), Err(TryRecvError::Disconnected));
+        t.join().unwrap();
+    }
+
+    // This bug used to end up in a livelock inside of the Receiver destructor
+    // because the internal state of the Shared packet was corrupted
+    #[test]
+    fn destroy_upgraded_shared_port_when_sender_still_active() {
+        let (tx, rx) = channel();
+        let (tx2, rx2) = channel();
+        let t = thread::spawn(move || {
+            rx.recv().unwrap(); // wait on a oneshot
+            drop(rx); // destroy a shared
+            tx2.send(()).unwrap();
+        });
+        // make sure the other thread has gone to sleep
+        for _ in 0..5000 {
+            thread::yield_now();
+        }
+
+        // upgrade to a shared chan and send a message
+        let tx2 = tx.clone();
+        drop(tx);
+        tx2.send(()).unwrap();
+
+        // wait for the child thread to exit before we exit
+        rx2.recv().unwrap();
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn issue_32114() {
+        let (tx, _) = channel();
+        let _ = tx.send(123);
+        assert_eq!(tx.send(123), Err(SendError(123)));
+    }
+}
+
+// Source: https://github.com/rust-lang/rust/blob/master/src/libstd/sync/mpsc/mod.rs
+mod sync_channel_tests {
+    use super::*;
+
+    use std::env;
+    use std::thread;
+    use std::time::Duration;
+
+    pub fn stress_factor() -> usize {
+        match env::var("RUST_TEST_STRESS") {
+            Ok(val) => val.parse().unwrap(),
+            Err(..) => 1,
+        }
+    }
+
+    #[test]
+    fn smoke() {
+        let (tx, rx) = sync_channel::<i32>(1);
+        tx.send(1).unwrap();
+        assert_eq!(rx.recv().unwrap(), 1);
+    }
+
+    #[test]
+    fn drop_full() {
+        let (tx, _rx) = sync_channel::<Box<isize>>(1);
+        tx.send(Box::new(1)).unwrap();
+    }
+
+    #[test]
+    fn smoke_shared() {
+        let (tx, rx) = sync_channel::<i32>(1);
+        tx.send(1).unwrap();
+        assert_eq!(rx.recv().unwrap(), 1);
+        let tx = tx.clone();
+        tx.send(1).unwrap();
+        assert_eq!(rx.recv().unwrap(), 1);
+    }
+
+    #[test]
+    fn recv_timeout() {
+        let (tx, rx) = sync_channel::<i32>(1);
+        assert_eq!(
+            rx.recv_timeout(Duration::from_millis(1)),
+            Err(RecvTimeoutError::Timeout)
+        );
+        tx.send(1).unwrap();
+        assert_eq!(rx.recv_timeout(Duration::from_millis(1)), Ok(1));
+    }
+
+    #[test]
+    fn smoke_threads() {
+        let (tx, rx) = sync_channel::<i32>(0);
+        let t = thread::spawn(move || {
+            tx.send(1).unwrap();
+        });
+        assert_eq!(rx.recv().unwrap(), 1);
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn smoke_port_gone() {
+        let (tx, rx) = sync_channel::<i32>(0);
+        drop(rx);
+        assert!(tx.send(1).is_err());
+    }
+
+    #[test]
+    fn smoke_shared_port_gone2() {
+        let (tx, rx) = sync_channel::<i32>(0);
+        drop(rx);
+        let tx2 = tx.clone();
+        drop(tx);
+        assert!(tx2.send(1).is_err());
+    }
+
+    #[test]
+    fn port_gone_concurrent() {
+        let (tx, rx) = sync_channel::<i32>(0);
+        let t = thread::spawn(move || {
+            rx.recv().unwrap();
+        });
+        while tx.send(1).is_ok() {}
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn port_gone_concurrent_shared() {
+        let (tx, rx) = sync_channel::<i32>(0);
+        let tx2 = tx.clone();
+        let t = thread::spawn(move || {
+            rx.recv().unwrap();
+        });
+        while tx.send(1).is_ok() && tx2.send(1).is_ok() {}
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn smoke_chan_gone() {
+        let (tx, rx) = sync_channel::<i32>(0);
+        drop(tx);
+        assert!(rx.recv().is_err());
+    }
+
+    #[test]
+    fn smoke_chan_gone_shared() {
+        let (tx, rx) = sync_channel::<()>(0);
+        let tx2 = tx.clone();
+        drop(tx);
+        drop(tx2);
+        assert!(rx.recv().is_err());
+    }
+
+    #[test]
+    fn chan_gone_concurrent() {
+        let (tx, rx) = sync_channel::<i32>(0);
+        let t = thread::spawn(move || {
+            tx.send(1).unwrap();
+            tx.send(1).unwrap();
+        });
+        while rx.recv().is_ok() {}
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn stress() {
+        let (tx, rx) = sync_channel::<i32>(0);
+        let t = thread::spawn(move || {
+            for _ in 0..10000 {
+                tx.send(1).unwrap();
+            }
+        });
+        for _ in 0..10000 {
+            assert_eq!(rx.recv().unwrap(), 1);
+        }
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn stress_recv_timeout_two_threads() {
+        let (tx, rx) = sync_channel::<i32>(0);
+
+        let t = thread::spawn(move || {
+            for _ in 0..10000 {
+                tx.send(1).unwrap();
+            }
+        });
+
+        let mut recv_count = 0;
+        loop {
+            match rx.recv_timeout(Duration::from_millis(1)) {
+                Ok(v) => {
+                    assert_eq!(v, 1);
+                    recv_count += 1;
+                }
+                Err(RecvTimeoutError::Timeout) => continue,
+                Err(RecvTimeoutError::Disconnected) => break,
+            }
+        }
+
+        assert_eq!(recv_count, 10000);
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn stress_recv_timeout_shared() {
+        const AMT: u32 = 1000;
+        const NTHREADS: u32 = 8;
+        let (tx, rx) = sync_channel::<i32>(0);
+        let (dtx, drx) = sync_channel::<()>(0);
+
+        let t = thread::spawn(move || {
+            let mut recv_count = 0;
+            loop {
+                match rx.recv_timeout(Duration::from_millis(10)) {
+                    Ok(v) => {
+                        assert_eq!(v, 1);
+                        recv_count += 1;
+                    }
+                    Err(RecvTimeoutError::Timeout) => continue,
+                    Err(RecvTimeoutError::Disconnected) => break,
+                }
+            }
+
+            assert_eq!(recv_count, AMT * NTHREADS);
+            assert!(rx.try_recv().is_err());
+
+            dtx.send(()).unwrap();
+        });
+
+        let mut ts = Vec::with_capacity(NTHREADS as usize);
+        for _ in 0..NTHREADS {
+            let tx = tx.clone();
+            let t = thread::spawn(move || {
+                for _ in 0..AMT {
+                    tx.send(1).unwrap();
+                }
+            });
+            ts.push(t);
+        }
+
+        drop(tx);
+
+        drx.recv().unwrap();
+        for t in ts {
+            t.join().unwrap();
+        }
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn stress_shared() {
+        const AMT: u32 = 1000;
+        const NTHREADS: u32 = 8;
+        let (tx, rx) = sync_channel::<i32>(0);
+        let (dtx, drx) = sync_channel::<()>(0);
+
+        let t = thread::spawn(move || {
+            for _ in 0..AMT * NTHREADS {
+                assert_eq!(rx.recv().unwrap(), 1);
+            }
+            match rx.try_recv() {
+                Ok(..) => panic!(),
+                _ => {}
+            }
+            dtx.send(()).unwrap();
+        });
+
+        let mut ts = Vec::with_capacity(NTHREADS as usize);
+        for _ in 0..NTHREADS {
+            let tx = tx.clone();
+            let t = thread::spawn(move || {
+                for _ in 0..AMT {
+                    tx.send(1).unwrap();
+                }
+            });
+            ts.push(t);
+        }
+        drop(tx);
+        drx.recv().unwrap();
+        for t in ts {
+            t.join().unwrap();
+        }
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn oneshot_single_thread_close_port_first() {
+        // Simple test of closing without sending
+        let (_tx, rx) = sync_channel::<i32>(0);
+        drop(rx);
+    }
+
+    #[test]
+    fn oneshot_single_thread_close_chan_first() {
+        // Simple test of closing without sending
+        let (tx, _rx) = sync_channel::<i32>(0);
+        drop(tx);
+    }
+
+    #[test]
+    fn oneshot_single_thread_send_port_close() {
+        // Testing that the sender cleans up the payload if receiver is closed
+        let (tx, rx) = sync_channel::<Box<i32>>(0);
+        drop(rx);
+        assert!(tx.send(Box::new(0)).is_err());
+    }
+
+    #[test]
+    fn oneshot_single_thread_recv_chan_close() {
+        let (tx, rx) = sync_channel::<i32>(0);
+        drop(tx);
+        assert_eq!(rx.recv(), Err(RecvError));
+    }
+
+    #[test]
+    fn oneshot_single_thread_send_then_recv() {
+        let (tx, rx) = sync_channel::<Box<i32>>(1);
+        tx.send(Box::new(10)).unwrap();
+        assert!(*rx.recv().unwrap() == 10);
+    }
+
+    #[test]
+    fn oneshot_single_thread_try_send_open() {
+        let (tx, rx) = sync_channel::<i32>(1);
+        assert_eq!(tx.try_send(10), Ok(()));
+        assert!(rx.recv().unwrap() == 10);
+    }
+
+    #[test]
+    fn oneshot_single_thread_try_send_closed() {
+        let (tx, rx) = sync_channel::<i32>(0);
+        drop(rx);
+        assert_eq!(tx.try_send(10), Err(TrySendError::Disconnected(10)));
+    }
+
+    #[test]
+    fn oneshot_single_thread_try_send_closed2() {
+        let (tx, _rx) = sync_channel::<i32>(0);
+        assert_eq!(tx.try_send(10), Err(TrySendError::Full(10)));
+    }
+
+    #[test]
+    fn oneshot_single_thread_try_recv_open() {
+        let (tx, rx) = sync_channel::<i32>(1);
+        tx.send(10).unwrap();
+        assert!(rx.recv() == Ok(10));
+    }
+
+    #[test]
+    fn oneshot_single_thread_try_recv_closed() {
+        let (tx, rx) = sync_channel::<i32>(0);
+        drop(tx);
+        assert!(rx.recv().is_err());
+    }
+
+    #[test]
+    fn oneshot_single_thread_try_recv_closed_with_data() {
+        let (tx, rx) = sync_channel::<i32>(1);
+        tx.send(10).unwrap();
+        drop(tx);
+        assert_eq!(rx.try_recv(), Ok(10));
+        assert_eq!(rx.try_recv(), Err(TryRecvError::Disconnected));
+    }
+
+    #[test]
+    fn oneshot_single_thread_peek_data() {
+        let (tx, rx) = sync_channel::<i32>(1);
+        assert_eq!(rx.try_recv(), Err(TryRecvError::Empty));
+        tx.send(10).unwrap();
+        assert_eq!(rx.try_recv(), Ok(10));
+    }
+
+    #[test]
+    fn oneshot_single_thread_peek_close() {
+        let (tx, rx) = sync_channel::<i32>(0);
+        drop(tx);
+        assert_eq!(rx.try_recv(), Err(TryRecvError::Disconnected));
+        assert_eq!(rx.try_recv(), Err(TryRecvError::Disconnected));
+    }
+
+    #[test]
+    fn oneshot_single_thread_peek_open() {
+        let (_tx, rx) = sync_channel::<i32>(0);
+        assert_eq!(rx.try_recv(), Err(TryRecvError::Empty));
+    }
+
+    #[test]
+    fn oneshot_multi_task_recv_then_send() {
+        let (tx, rx) = sync_channel::<Box<i32>>(0);
+        let t = thread::spawn(move || {
+            assert!(*rx.recv().unwrap() == 10);
+        });
+
+        tx.send(Box::new(10)).unwrap();
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn oneshot_multi_task_recv_then_close() {
+        let (tx, rx) = sync_channel::<Box<i32>>(0);
+        let t = thread::spawn(move || {
+            drop(tx);
+        });
+        thread::spawn(move || {
+            assert_eq!(rx.recv(), Err(RecvError));
+        })
+        .join()
+        .unwrap();
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn oneshot_multi_thread_close_stress() {
+        let stress_factor = stress_factor();
+        let mut ts = Vec::with_capacity(stress_factor);
+        for _ in 0..stress_factor {
+            let (tx, rx) = sync_channel::<i32>(0);
+            let t = thread::spawn(move || {
+                drop(rx);
+            });
+            ts.push(t);
+            drop(tx);
+        }
+        for t in ts {
+            t.join().unwrap();
+        }
+    }
+
+    #[test]
+    fn oneshot_multi_thread_send_close_stress() {
+        let stress_factor = stress_factor();
+        let mut ts = Vec::with_capacity(stress_factor);
+        for _ in 0..stress_factor {
+            let (tx, rx) = sync_channel::<i32>(0);
+            let t = thread::spawn(move || {
+                drop(rx);
+            });
+            ts.push(t);
+            thread::spawn(move || {
+                let _ = tx.send(1);
+            })
+            .join()
+            .unwrap();
+        }
+        for t in ts {
+            t.join().unwrap();
+        }
+    }
+
+    #[test]
+    fn oneshot_multi_thread_recv_close_stress() {
+        let stress_factor = stress_factor();
+        let mut ts = Vec::with_capacity(2 * stress_factor);
+        for _ in 0..stress_factor {
+            let (tx, rx) = sync_channel::<i32>(0);
+            let t = thread::spawn(move || {
+                thread::spawn(move || {
+                    assert_eq!(rx.recv(), Err(RecvError));
+                })
+                .join()
+                .unwrap();
+            });
+            ts.push(t);
+            let t2 = thread::spawn(move || {
+                thread::spawn(move || {
+                    drop(tx);
+                });
+            });
+            ts.push(t2);
+        }
+        for t in ts {
+            t.join().unwrap();
+        }
+    }
+
+    #[test]
+    fn oneshot_multi_thread_send_recv_stress() {
+        let stress_factor = stress_factor();
+        let mut ts = Vec::with_capacity(stress_factor);
+        for _ in 0..stress_factor {
+            let (tx, rx) = sync_channel::<Box<i32>>(0);
+            let t = thread::spawn(move || {
+                tx.send(Box::new(10)).unwrap();
+            });
+            ts.push(t);
+            assert!(*rx.recv().unwrap() == 10);
+        }
+        for t in ts {
+            t.join().unwrap();
+        }
+    }
+
+    #[test]
+    fn stream_send_recv_stress() {
+        let stress_factor = stress_factor();
+        let mut ts = Vec::with_capacity(2 * stress_factor);
+        for _ in 0..stress_factor {
+            let (tx, rx) = sync_channel::<Box<i32>>(0);
+
+            if let Some(t) = send(tx, 0) {
+                ts.push(t);
+            }
+            if let Some(t) = recv(rx, 0) {
+                ts.push(t);
+            }
+
+            fn send(tx: SyncSender<Box<i32>>, i: i32) -> Option<JoinHandle<()>> {
+                if i == 10 {
+                    return None;
+                }
+
+                Some(thread::spawn(move || {
+                    tx.send(Box::new(i)).unwrap();
+                    send(tx, i + 1);
+                }))
+            }
+
+            fn recv(rx: Receiver<Box<i32>>, i: i32) -> Option<JoinHandle<()>> {
+                if i == 10 {
+                    return None;
+                }
+
+                Some(thread::spawn(move || {
+                    assert!(*rx.recv().unwrap() == i);
+                    recv(rx, i + 1);
+                }))
+            }
+        }
+        for t in ts {
+            t.join().unwrap();
+        }
+    }
+
+    #[test]
+    fn recv_a_lot() {
+        // Regression test that we don't run out of stack in scheduler context
+        let (tx, rx) = sync_channel(10000);
+        for _ in 0..10000 {
+            tx.send(()).unwrap();
+        }
+        for _ in 0..10000 {
+            rx.recv().unwrap();
+        }
+    }
+
+    #[test]
+    fn shared_chan_stress() {
+        let (tx, rx) = sync_channel(0);
+        let total = stress_factor() + 100;
+        let mut ts = Vec::with_capacity(total);
+        for _ in 0..total {
+            let tx = tx.clone();
+            let t = thread::spawn(move || {
+                tx.send(()).unwrap();
+            });
+            ts.push(t);
+        }
+
+        for _ in 0..total {
+            rx.recv().unwrap();
+        }
+        for t in ts {
+            t.join().unwrap();
+        }
+    }
+
+    #[test]
+    fn test_nested_recv_iter() {
+        let (tx, rx) = sync_channel::<i32>(0);
+        let (total_tx, total_rx) = sync_channel::<i32>(0);
+
+        let t = thread::spawn(move || {
+            let mut acc = 0;
+            for x in rx.iter() {
+                acc += x;
+            }
+            total_tx.send(acc).unwrap();
+        });
+
+        tx.send(3).unwrap();
+        tx.send(1).unwrap();
+        tx.send(2).unwrap();
+        drop(tx);
+        assert_eq!(total_rx.recv().unwrap(), 6);
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn test_recv_iter_break() {
+        let (tx, rx) = sync_channel::<i32>(0);
+        let (count_tx, count_rx) = sync_channel(0);
+
+        let t = thread::spawn(move || {
+            let mut count = 0;
+            for x in rx.iter() {
+                if count >= 3 {
+                    break;
+                } else {
+                    count += x;
+                }
+            }
+            count_tx.send(count).unwrap();
+        });
+
+        tx.send(2).unwrap();
+        tx.send(2).unwrap();
+        tx.send(2).unwrap();
+        let _ = tx.try_send(2);
+        drop(tx);
+        assert_eq!(count_rx.recv().unwrap(), 4);
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn try_recv_states() {
+        let (tx1, rx1) = sync_channel::<i32>(1);
+        let (tx2, rx2) = sync_channel::<()>(1);
+        let (tx3, rx3) = sync_channel::<()>(1);
+        let t = thread::spawn(move || {
+            rx2.recv().unwrap();
+            tx1.send(1).unwrap();
+            tx3.send(()).unwrap();
+            rx2.recv().unwrap();
+            drop(tx1);
+            tx3.send(()).unwrap();
+        });
+
+        assert_eq!(rx1.try_recv(), Err(TryRecvError::Empty));
+        tx2.send(()).unwrap();
+        rx3.recv().unwrap();
+        assert_eq!(rx1.try_recv(), Ok(1));
+        assert_eq!(rx1.try_recv(), Err(TryRecvError::Empty));
+        tx2.send(()).unwrap();
+        rx3.recv().unwrap();
+        assert_eq!(rx1.try_recv(), Err(TryRecvError::Disconnected));
+        t.join().unwrap();
+    }
+
+    // This bug used to end up in a livelock inside of the Receiver destructor
+    // because the internal state of the Shared packet was corrupted
+    #[test]
+    fn destroy_upgraded_shared_port_when_sender_still_active() {
+        let (tx, rx) = sync_channel::<()>(0);
+        let (tx2, rx2) = sync_channel::<()>(0);
+        let t = thread::spawn(move || {
+            rx.recv().unwrap(); // wait on a oneshot
+            drop(rx); // destroy a shared
+            tx2.send(()).unwrap();
+        });
+        // make sure the other thread has gone to sleep
+        for _ in 0..5000 {
+            thread::yield_now();
+        }
+
+        // upgrade to a shared chan and send a message
+        let tx2 = tx.clone();
+        drop(tx);
+        tx2.send(()).unwrap();
+
+        // wait for the child thread to exit before we exit
+        rx2.recv().unwrap();
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn send1() {
+        let (tx, rx) = sync_channel::<i32>(0);
+        let t = thread::spawn(move || {
+            rx.recv().unwrap();
+        });
+        assert_eq!(tx.send(1), Ok(()));
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn send2() {
+        let (tx, rx) = sync_channel::<i32>(0);
+        let t = thread::spawn(move || {
+            drop(rx);
+        });
+        assert!(tx.send(1).is_err());
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn send3() {
+        let (tx, rx) = sync_channel::<i32>(1);
+        assert_eq!(tx.send(1), Ok(()));
+        let t = thread::spawn(move || {
+            drop(rx);
+        });
+        assert!(tx.send(1).is_err());
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn send4() {
+        let (tx, rx) = sync_channel::<i32>(0);
+        let tx2 = tx.clone();
+        let (done, donerx) = channel();
+        let done2 = done.clone();
+        let t = thread::spawn(move || {
+            assert!(tx.send(1).is_err());
+            done.send(()).unwrap();
+        });
+        let t2 = thread::spawn(move || {
+            assert!(tx2.send(2).is_err());
+            done2.send(()).unwrap();
+        });
+        drop(rx);
+        donerx.recv().unwrap();
+        donerx.recv().unwrap();
+        t.join().unwrap();
+        t2.join().unwrap();
+    }
+
+    #[test]
+    fn try_send1() {
+        let (tx, _rx) = sync_channel::<i32>(0);
+        assert_eq!(tx.try_send(1), Err(TrySendError::Full(1)));
+    }
+
+    #[test]
+    fn try_send2() {
+        let (tx, _rx) = sync_channel::<i32>(1);
+        assert_eq!(tx.try_send(1), Ok(()));
+        assert_eq!(tx.try_send(1), Err(TrySendError::Full(1)));
+    }
+
+    #[test]
+    fn try_send3() {
+        let (tx, rx) = sync_channel::<i32>(1);
+        assert_eq!(tx.try_send(1), Ok(()));
+        drop(rx);
+        assert_eq!(tx.try_send(1), Err(TrySendError::Disconnected(1)));
+    }
+
+    #[test]
+    fn issue_15761() {
+        fn repro() {
+            let (tx1, rx1) = sync_channel::<()>(3);
+            let (tx2, rx2) = sync_channel::<()>(3);
+
+            let _t = thread::spawn(move || {
+                rx1.recv().unwrap();
+                tx2.try_send(()).unwrap();
+            });
+
+            tx1.try_send(()).unwrap();
+            rx2.recv().unwrap();
+        }
+
+        for _ in 0..100 {
+            repro()
+        }
+    }
+}
+
+// Source: https://github.com/rust-lang/rust/blob/master/src/libstd/sync/mpsc/select.rs
+mod select_tests {
+    use super::*;
+
+    use std::thread;
+
+    #[test]
+    fn smoke() {
+        let (tx1, rx1) = channel::<i32>();
+        let (tx2, rx2) = channel::<i32>();
+        tx1.send(1).unwrap();
+        select! {
+            foo = rx1.recv() => { assert_eq!(foo.unwrap(), 1); },
+            _bar = rx2.recv() => { panic!() }
+        }
+        tx2.send(2).unwrap();
+        select! {
+            _foo = rx1.recv() => { panic!() },
+            bar = rx2.recv() => { assert_eq!(bar.unwrap(), 2) }
+        }
+        drop(tx1);
+        select! {
+            foo = rx1.recv() => { assert!(foo.is_err()); },
+            _bar = rx2.recv() => { panic!() }
+        }
+        drop(tx2);
+        select! {
+            bar = rx2.recv() => { assert!(bar.is_err()); }
+        }
+    }
+
+    #[test]
+    fn smoke2() {
+        let (_tx1, rx1) = channel::<i32>();
+        let (_tx2, rx2) = channel::<i32>();
+        let (_tx3, rx3) = channel::<i32>();
+        let (_tx4, rx4) = channel::<i32>();
+        let (tx5, rx5) = channel::<i32>();
+        tx5.send(4).unwrap();
+        select! {
+            _foo = rx1.recv() => { panic!("1") },
+            _foo = rx2.recv() => { panic!("2") },
+            _foo = rx3.recv() => { panic!("3") },
+            _foo = rx4.recv() => { panic!("4") },
+            foo = rx5.recv() => { assert_eq!(foo.unwrap(), 4); }
+        }
+    }
+
+    #[test]
+    fn closed() {
+        let (_tx1, rx1) = channel::<i32>();
+        let (tx2, rx2) = channel::<i32>();
+        drop(tx2);
+
+        select! {
+            _a1 = rx1.recv() => { panic!() },
+            a2 = rx2.recv() => { assert!(a2.is_err()); }
+        }
+    }
+
+    #[test]
+    fn unblocks() {
+        let (tx1, rx1) = channel::<i32>();
+        let (_tx2, rx2) = channel::<i32>();
+        let (tx3, rx3) = channel::<i32>();
+
+        let t = thread::spawn(move || {
+            for _ in 0..20 {
+                thread::yield_now();
+            }
+            tx1.send(1).unwrap();
+            rx3.recv().unwrap();
+            for _ in 0..20 {
+                thread::yield_now();
+            }
+        });
+
+        select! {
+            a = rx1.recv() => { assert_eq!(a.unwrap(), 1); },
+            _b = rx2.recv() => { panic!() }
+        }
+        tx3.send(1).unwrap();
+        select! {
+            a = rx1.recv() => { assert!(a.is_err()) },
+            _b = rx2.recv() => { panic!() }
+        }
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn both_ready() {
+        let (tx1, rx1) = channel::<i32>();
+        let (tx2, rx2) = channel::<i32>();
+        let (tx3, rx3) = channel::<()>();
+
+        let t = thread::spawn(move || {
+            for _ in 0..20 {
+                thread::yield_now();
+            }
+            tx1.send(1).unwrap();
+            tx2.send(2).unwrap();
+            rx3.recv().unwrap();
+        });
+
+        select! {
+            a = rx1.recv() => { assert_eq!(a.unwrap(), 1); },
+            a = rx2.recv() => { assert_eq!(a.unwrap(), 2); }
+        }
+        select! {
+            a = rx1.recv() => { assert_eq!(a.unwrap(), 1); },
+            a = rx2.recv() => { assert_eq!(a.unwrap(), 2); }
+        }
+        assert_eq!(rx1.try_recv(), Err(TryRecvError::Empty));
+        assert_eq!(rx2.try_recv(), Err(TryRecvError::Empty));
+        tx3.send(()).unwrap();
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn stress() {
+        const AMT: i32 = 10000;
+        let (tx1, rx1) = channel::<i32>();
+        let (tx2, rx2) = channel::<i32>();
+        let (tx3, rx3) = channel::<()>();
+
+        let t = thread::spawn(move || {
+            for i in 0..AMT {
+                if i % 2 == 0 {
+                    tx1.send(i).unwrap();
+                } else {
+                    tx2.send(i).unwrap();
+                }
+                rx3.recv().unwrap();
+            }
+        });
+
+        for i in 0..AMT {
+            select! {
+                i1 = rx1.recv() => { assert!(i % 2 == 0 && i == i1.unwrap()); },
+                i2 = rx2.recv() => { assert!(i % 2 == 1 && i == i2.unwrap()); }
+            }
+            tx3.send(()).unwrap();
+        }
+        t.join().unwrap();
+    }
+
+    #[allow(unused_must_use)]
+    #[test]
+    fn cloning() {
+        let (tx1, rx1) = channel::<i32>();
+        let (_tx2, rx2) = channel::<i32>();
+        let (tx3, rx3) = channel::<()>();
+
+        let t = thread::spawn(move || {
+            rx3.recv().unwrap();
+            tx1.clone();
+            assert_eq!(rx3.try_recv(), Err(TryRecvError::Empty));
+            tx1.send(2).unwrap();
+            rx3.recv().unwrap();
+        });
+
+        tx3.send(()).unwrap();
+        select! {
+            _i1 = rx1.recv() => {},
+            _i2 = rx2.recv() => panic!()
+        }
+        tx3.send(()).unwrap();
+        t.join().unwrap();
+    }
+
+    #[allow(unused_must_use)]
+    #[test]
+    fn cloning2() {
+        let (tx1, rx1) = channel::<i32>();
+        let (_tx2, rx2) = channel::<i32>();
+        let (tx3, rx3) = channel::<()>();
+
+        let t = thread::spawn(move || {
+            rx3.recv().unwrap();
+            tx1.clone();
+            assert_eq!(rx3.try_recv(), Err(TryRecvError::Empty));
+            tx1.send(2).unwrap();
+            rx3.recv().unwrap();
+        });
+
+        tx3.send(()).unwrap();
+        select! {
+            _i1 = rx1.recv() => {},
+            _i2 = rx2.recv() => panic!()
+        }
+        tx3.send(()).unwrap();
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn cloning3() {
+        let (tx1, rx1) = channel::<()>();
+        let (tx2, rx2) = channel::<()>();
+        let (tx3, rx3) = channel::<()>();
+        let t = thread::spawn(move || {
+            select! {
+                _ = rx1.recv() => panic!(),
+                _ = rx2.recv() => {}
+            }
+            tx3.send(()).unwrap();
+        });
+
+        for _ in 0..1000 {
+            thread::yield_now();
+        }
+        drop(tx1.clone());
+        tx2.send(()).unwrap();
+        rx3.recv().unwrap();
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn preflight1() {
+        let (tx, rx) = channel();
+        tx.send(()).unwrap();
+        select! {
+            _n = rx.recv() => {}
+        }
+    }
+
+    #[test]
+    fn preflight2() {
+        let (tx, rx) = channel();
+        tx.send(()).unwrap();
+        tx.send(()).unwrap();
+        select! {
+            _n = rx.recv() => {}
+        }
+    }
+
+    #[test]
+    fn preflight3() {
+        let (tx, rx) = channel();
+        drop(tx.clone());
+        tx.send(()).unwrap();
+        select! {
+            _n = rx.recv() => {}
+        }
+    }
+
+    #[test]
+    fn preflight4() {
+        let (tx, rx) = channel();
+        tx.send(()).unwrap();
+        select! {
+            _ = rx.recv() => {}
+        }
+    }
+
+    #[test]
+    fn preflight5() {
+        let (tx, rx) = channel();
+        tx.send(()).unwrap();
+        tx.send(()).unwrap();
+        select! {
+            _ = rx.recv() => {}
+        }
+    }
+
+    #[test]
+    fn preflight6() {
+        let (tx, rx) = channel();
+        drop(tx.clone());
+        tx.send(()).unwrap();
+        select! {
+            _ = rx.recv() => {}
+        }
+    }
+
+    #[test]
+    fn preflight7() {
+        let (tx, rx) = channel::<()>();
+        drop(tx);
+        select! {
+            _ = rx.recv() => {}
+        }
+    }
+
+    #[test]
+    fn preflight8() {
+        let (tx, rx) = channel();
+        tx.send(()).unwrap();
+        drop(tx);
+        rx.recv().unwrap();
+        select! {
+            _ = rx.recv() => {}
+        }
+    }
+
+    #[test]
+    fn preflight9() {
+        let (tx, rx) = channel();
+        drop(tx.clone());
+        tx.send(()).unwrap();
+        drop(tx);
+        rx.recv().unwrap();
+        select! {
+            _ = rx.recv() => {}
+        }
+    }
+
+    #[test]
+    fn oneshot_data_waiting() {
+        let (tx1, rx1) = channel();
+        let (tx2, rx2) = channel();
+        let t = thread::spawn(move || {
+            select! {
+                _n = rx1.recv() => {}
+            }
+            tx2.send(()).unwrap();
+        });
+
+        for _ in 0..100 {
+            thread::yield_now()
+        }
+        tx1.send(()).unwrap();
+        rx2.recv().unwrap();
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn stream_data_waiting() {
+        let (tx1, rx1) = channel();
+        let (tx2, rx2) = channel();
+        tx1.send(()).unwrap();
+        tx1.send(()).unwrap();
+        rx1.recv().unwrap();
+        rx1.recv().unwrap();
+        let t = thread::spawn(move || {
+            select! {
+                _n = rx1.recv() => {}
+            }
+            tx2.send(()).unwrap();
+        });
+
+        for _ in 0..100 {
+            thread::yield_now()
+        }
+        tx1.send(()).unwrap();
+        rx2.recv().unwrap();
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn shared_data_waiting() {
+        let (tx1, rx1) = channel();
+        let (tx2, rx2) = channel();
+        drop(tx1.clone());
+        tx1.send(()).unwrap();
+        rx1.recv().unwrap();
+        let t = thread::spawn(move || {
+            select! {
+                _n = rx1.recv() => {}
+            }
+            tx2.send(()).unwrap();
+        });
+
+        for _ in 0..100 {
+            thread::yield_now()
+        }
+        tx1.send(()).unwrap();
+        rx2.recv().unwrap();
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn sync1() {
+        let (tx, rx) = sync_channel::<i32>(1);
+        tx.send(1).unwrap();
+        select! {
+            n = rx.recv() => { assert_eq!(n.unwrap(), 1); }
+        }
+    }
+
+    #[test]
+    fn sync2() {
+        let (tx, rx) = sync_channel::<i32>(0);
+        let t = thread::spawn(move || {
+            for _ in 0..100 {
+                thread::yield_now()
+            }
+            tx.send(1).unwrap();
+        });
+        select! {
+            n = rx.recv() => { assert_eq!(n.unwrap(), 1); }
+        }
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn sync3() {
+        let (tx1, rx1) = sync_channel::<i32>(0);
+        let (tx2, rx2): (Sender<i32>, Receiver<i32>) = channel();
+        let t = thread::spawn(move || {
+            tx1.send(1).unwrap();
+        });
+        let t2 = thread::spawn(move || {
+            tx2.send(2).unwrap();
+        });
+        select! {
+            n = rx1.recv() => {
+                let n = n.unwrap();
+                assert_eq!(n, 1);
+                assert_eq!(rx2.recv().unwrap(), 2);
+            },
+            n = rx2.recv() => {
+                let n = n.unwrap();
+                assert_eq!(n, 2);
+                assert_eq!(rx1.recv().unwrap(), 1);
+            }
+        }
+        t.join().unwrap();
+        t2.join().unwrap();
+    }
+}