std: move "mod tests/benches" to separate files

Also doing fmt inplace as requested.

7 files changed, 1513 insertions, 1517 deletions

diff --git a/library/std/src/sync/mpsc/mod.rs b/library/std/src/sync/mpsc/mod.rs
index ac83017d9e1..073f969bbe2 100644
--- a/library/std/src/sync/mpsc/mod.rs
+++ b/library/std/src/sync/mpsc/mod.rs
@@ -108,6 +108,12 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
+#[cfg(all(test, not(target_os = "emscripten")))]
+mod tests;
+
+#[cfg(all(test, not(target_os = "emscripten")))]
+mod sync_tests;
+
 // A description of how Rust's channel implementation works
 //
 // Channels are supposed to be the basic building block for all other
@@ -1606,1364 +1612,3 @@ impl From<RecvError> for RecvTimeoutError {
         }
     }
 }
-
-#[cfg(all(test, not(target_os = "emscripten")))]
-mod tests {
-    use super::*;
-    use crate::env;
-    use crate::thread;
-    use crate::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 1).unwrap();
-    }
-
-    #[test]
-    fn drop_full_shared() {
-        let (tx, _rx) = channel::<Box<isize>>();
-        drop(tx.clone());
-        drop(tx.clone());
-        tx.send(box 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);
-    }
-
-    #[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() {}
-    }
-
-    #[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() {}
-    }
-
-    #[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() {}
-    }
-
-    #[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().expect("thread panicked");
-    }
-
-    #[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!(),
-                _ => {}
-            }
-        });
-
-        for _ in 0..NTHREADS {
-            let tx = tx.clone();
-            thread::spawn(move || {
-                for _ in 0..AMT {
-                    tx.send(1).unwrap();
-                }
-            });
-        }
-        drop(tx);
-        t.join().ok().expect("thread panicked");
-    }
-
-    #[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().expect("thread panicked");
-        t2.join().ok().expect("thread panicked");
-    }
-
-    #[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().expect("thread panicked");
-    }
-
-    #[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().expect("thread panicked");
-        t2.join().ok().expect("thread panicked");
-    }
-
-    #[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 0).is_err());
-    }
-
-    #[test]
-    fn oneshot_single_thread_recv_chan_close() {
-        // Receiving on a closed chan will panic
-        let res = thread::spawn(move || {
-            let (tx, rx) = channel::<i32>();
-            drop(tx);
-            rx.recv().unwrap();
-        })
-        .join();
-        // What is our res?
-        assert!(res.is_err());
-    }
-
-    #[test]
-    fn oneshot_single_thread_send_then_recv() {
-        let (tx, rx) = channel::<Box<i32>>();
-        tx.send(box 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 10).unwrap();
-    }
-
-    #[test]
-    fn oneshot_multi_task_recv_then_close() {
-        let (tx, rx) = channel::<Box<i32>>();
-        let _t = thread::spawn(move || {
-            drop(tx);
-        });
-        let res = thread::spawn(move || {
-            assert!(*rx.recv().unwrap() == 10);
-        })
-        .join();
-        assert!(res.is_err());
-    }
-
-    #[test]
-    fn oneshot_multi_thread_close_stress() {
-        for _ in 0..stress_factor() {
-            let (tx, rx) = channel::<i32>();
-            let _t = thread::spawn(move || {
-                drop(rx);
-            });
-            drop(tx);
-        }
-    }
-
-    #[test]
-    fn oneshot_multi_thread_send_close_stress() {
-        for _ in 0..stress_factor() {
-            let (tx, rx) = channel::<i32>();
-            let _t = thread::spawn(move || {
-                drop(rx);
-            });
-            let _ = thread::spawn(move || {
-                tx.send(1).unwrap();
-            })
-            .join();
-        }
-    }
-
-    #[test]
-    fn oneshot_multi_thread_recv_close_stress() {
-        for _ in 0..stress_factor() {
-            let (tx, rx) = channel::<i32>();
-            thread::spawn(move || {
-                let res = thread::spawn(move || {
-                    rx.recv().unwrap();
-                })
-                .join();
-                assert!(res.is_err());
-            });
-            let _t = thread::spawn(move || {
-                thread::spawn(move || {
-                    drop(tx);
-                });
-            });
-        }
-    }
-
-    #[test]
-    fn oneshot_multi_thread_send_recv_stress() {
-        for _ in 0..stress_factor() {
-            let (tx, rx) = channel::<Box<isize>>();
-            let _t = thread::spawn(move || {
-                tx.send(box 10).unwrap();
-            });
-            assert!(*rx.recv().unwrap() == 10);
-        }
-    }
-
-    #[test]
-    fn stream_send_recv_stress() {
-        for _ in 0..stress_factor() {
-            let (tx, rx) = channel();
-
-            send(tx, 0);
-            recv(rx, 0);
-
-            fn send(tx: Sender<Box<i32>>, i: i32) {
-                if i == 10 {
-                    return;
-                }
-
-                thread::spawn(move || {
-                    tx.send(box i).unwrap();
-                    send(tx, i + 1);
-                });
-            }
-
-            fn recv(rx: Receiver<Box<i32>>, i: i32) {
-                if i == 10 {
-                    return;
-                }
-
-                thread::spawn(move || {
-                    assert!(*rx.recv().unwrap() == i);
-                    recv(rx, i + 1);
-                });
-            }
-        }
-    }
-
-    #[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);
-
-        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);
-    }
-
-    #[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;
-
-        for i in 0..stress {
-            let tx = tx.clone();
-            thread::spawn(move || {
-                thread::sleep(Duration::from_millis(i as u64 * 10));
-                tx.send(1usize).unwrap();
-            });
-        }
-
-        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);
-    }
-
-    #[test]
-    fn very_long_recv_timeout_wont_panic() {
-        let (tx, rx) = channel::<()>();
-        let join_handle = thread::spawn(move || rx.recv_timeout(Duration::from_secs(u64::MAX)));
-        thread::sleep(Duration::from_secs(1));
-        assert!(tx.send(()).is_ok());
-        assert_eq!(join_handle.join().unwrap(), Ok(()));
-    }
-
-    #[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;
-        for _ in 0..total {
-            let tx = tx.clone();
-            thread::spawn(move || {
-                tx.send(()).unwrap();
-            });
-        }
-
-        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(()));
-    }
-
-    #[test]
-    fn shared_chan_stress() {
-        let (tx, rx) = channel();
-        let total = stress_factor() + 100;
-        for _ in 0..total {
-            let tx = tx.clone();
-            thread::spawn(move || {
-                tx.send(()).unwrap();
-            });
-        }
-
-        for _ in 0..total {
-            rx.recv().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);
-    }
-
-    #[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);
-    }
-
-    #[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));
-    }
-
-    // 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 t = tx.clone();
-        drop(tx);
-        t.send(()).unwrap();
-
-        // wait for the child thread to exit before we exit
-        rx2.recv().unwrap();
-    }
-
-    #[test]
-    fn issue_32114() {
-        let (tx, _) = channel();
-        let _ = tx.send(123);
-        assert_eq!(tx.send(123), Err(SendError(123)));
-    }
-}
-
-#[cfg(all(test, not(target_os = "emscripten")))]
-mod sync_tests {
-    use super::*;
-    use crate::env;
-    use crate::thread;
-    use crate::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 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);
-    }
-
-    #[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() {}
-    }
-
-    #[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() {}
-    }
-
-    #[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);
-        thread::spawn(move || {
-            tx.send(1).unwrap();
-            tx.send(1).unwrap();
-        });
-        while rx.recv().is_ok() {}
-    }
-
-    #[test]
-    fn stress() {
-        let (tx, rx) = sync_channel::<i32>(0);
-        thread::spawn(move || {
-            for _ in 0..10000 {
-                tx.send(1).unwrap();
-            }
-        });
-        for _ in 0..10000 {
-            assert_eq!(rx.recv().unwrap(), 1);
-        }
-    }
-
-    #[test]
-    fn stress_recv_timeout_two_threads() {
-        let (tx, rx) = sync_channel::<i32>(0);
-
-        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);
-    }
-
-    #[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);
-
-        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();
-        });
-
-        for _ in 0..NTHREADS {
-            let tx = tx.clone();
-            thread::spawn(move || {
-                for _ in 0..AMT {
-                    tx.send(1).unwrap();
-                }
-            });
-        }
-
-        drop(tx);
-
-        drx.recv().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);
-
-        thread::spawn(move || {
-            for _ in 0..AMT * NTHREADS {
-                assert_eq!(rx.recv().unwrap(), 1);
-            }
-            match rx.try_recv() {
-                Ok(..) => panic!(),
-                _ => {}
-            }
-            dtx.send(()).unwrap();
-        });
-
-        for _ in 0..NTHREADS {
-            let tx = tx.clone();
-            thread::spawn(move || {
-                for _ in 0..AMT {
-                    tx.send(1).unwrap();
-                }
-            });
-        }
-        drop(tx);
-        drx.recv().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 0).is_err());
-    }
-
-    #[test]
-    fn oneshot_single_thread_recv_chan_close() {
-        // Receiving on a closed chan will panic
-        let res = thread::spawn(move || {
-            let (tx, rx) = sync_channel::<i32>(0);
-            drop(tx);
-            rx.recv().unwrap();
-        })
-        .join();
-        // What is our res?
-        assert!(res.is_err());
-    }
-
-    #[test]
-    fn oneshot_single_thread_send_then_recv() {
-        let (tx, rx) = sync_channel::<Box<i32>>(1);
-        tx.send(box 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 10).unwrap();
-    }
-
-    #[test]
-    fn oneshot_multi_task_recv_then_close() {
-        let (tx, rx) = sync_channel::<Box<i32>>(0);
-        let _t = thread::spawn(move || {
-            drop(tx);
-        });
-        let res = thread::spawn(move || {
-            assert!(*rx.recv().unwrap() == 10);
-        })
-        .join();
-        assert!(res.is_err());
-    }
-
-    #[test]
-    fn oneshot_multi_thread_close_stress() {
-        for _ in 0..stress_factor() {
-            let (tx, rx) = sync_channel::<i32>(0);
-            let _t = thread::spawn(move || {
-                drop(rx);
-            });
-            drop(tx);
-        }
-    }
-
-    #[test]
-    fn oneshot_multi_thread_send_close_stress() {
-        for _ in 0..stress_factor() {
-            let (tx, rx) = sync_channel::<i32>(0);
-            let _t = thread::spawn(move || {
-                drop(rx);
-            });
-            let _ = thread::spawn(move || {
-                tx.send(1).unwrap();
-            })
-            .join();
-        }
-    }
-
-    #[test]
-    fn oneshot_multi_thread_recv_close_stress() {
-        for _ in 0..stress_factor() {
-            let (tx, rx) = sync_channel::<i32>(0);
-            let _t = thread::spawn(move || {
-                let res = thread::spawn(move || {
-                    rx.recv().unwrap();
-                })
-                .join();
-                assert!(res.is_err());
-            });
-            let _t = thread::spawn(move || {
-                thread::spawn(move || {
-                    drop(tx);
-                });
-            });
-        }
-    }
-
-    #[test]
-    fn oneshot_multi_thread_send_recv_stress() {
-        for _ in 0..stress_factor() {
-            let (tx, rx) = sync_channel::<Box<i32>>(0);
-            let _t = thread::spawn(move || {
-                tx.send(box 10).unwrap();
-            });
-            assert!(*rx.recv().unwrap() == 10);
-        }
-    }
-
-    #[test]
-    fn stream_send_recv_stress() {
-        for _ in 0..stress_factor() {
-            let (tx, rx) = sync_channel::<Box<i32>>(0);
-
-            send(tx, 0);
-            recv(rx, 0);
-
-            fn send(tx: SyncSender<Box<i32>>, i: i32) {
-                if i == 10 {
-                    return;
-                }
-
-                thread::spawn(move || {
-                    tx.send(box i).unwrap();
-                    send(tx, i + 1);
-                });
-            }
-
-            fn recv(rx: Receiver<Box<i32>>, i: i32) {
-                if i == 10 {
-                    return;
-                }
-
-                thread::spawn(move || {
-                    assert!(*rx.recv().unwrap() == i);
-                    recv(rx, i + 1);
-                });
-            }
-        }
-    }
-
-    #[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;
-        for _ in 0..total {
-            let tx = tx.clone();
-            thread::spawn(move || {
-                tx.send(()).unwrap();
-            });
-        }
-
-        for _ in 0..total {
-            rx.recv().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);
-    }
-
-    #[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);
-    }
-
-    #[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));
-    }
-
-    // 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 t = tx.clone();
-        drop(tx);
-        t.send(()).unwrap();
-
-        // wait for the child thread to exit before we exit
-        rx2.recv().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(()));
-    }
-
-    #[test]
-    fn send2() {
-        let (tx, rx) = sync_channel::<i32>(0);
-        let _t = thread::spawn(move || {
-            drop(rx);
-        });
-        assert!(tx.send(1).is_err());
-    }
-
-    #[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());
-    }
-
-    #[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 _t = thread::spawn(move || {
-            assert!(tx2.send(2).is_err());
-            done2.send(()).unwrap();
-        });
-        drop(rx);
-        donerx.recv().unwrap();
-        donerx.recv().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()
-        }
-    }
-}
diff --git a/library/std/src/sync/mpsc/mpsc_queue.rs b/library/std/src/sync/mpsc/mpsc_queue.rs
index 6e7a7be4430..42bc639dc25 100644
--- a/library/std/src/sync/mpsc/mpsc_queue.rs
+++ b/library/std/src/sync/mpsc/mpsc_queue.rs
@@ -11,6 +11,9 @@
 // http://www.1024cores.net/home/lock-free-algorithms
 //                         /queues/non-intrusive-mpsc-node-based-queue
 
+#[cfg(all(test, not(target_os = "emscripten")))]
+mod tests;
+
 pub use self::PopResult::*;
 
 use core::cell::UnsafeCell;
@@ -112,54 +115,3 @@ impl<T> Drop for Queue<T> {
         }
     }
 }
-
-#[cfg(all(test, not(target_os = "emscripten")))]
-mod tests {
-    use super::{Data, Empty, Inconsistent, Queue};
-    use crate::sync::mpsc::channel;
-    use crate::sync::Arc;
-    use crate::thread;
-
-    #[test]
-    fn test_full() {
-        let q: Queue<Box<_>> = Queue::new();
-        q.push(box 1);
-        q.push(box 2);
-    }
-
-    #[test]
-    fn test() {
-        let nthreads = 8;
-        let nmsgs = 1000;
-        let q = Queue::new();
-        match q.pop() {
-            Empty => {}
-            Inconsistent | Data(..) => panic!(),
-        }
-        let (tx, rx) = channel();
-        let q = Arc::new(q);
-
-        for _ in 0..nthreads {
-            let tx = tx.clone();
-            let q = q.clone();
-            thread::spawn(move || {
-                for i in 0..nmsgs {
-                    q.push(i);
-                }
-                tx.send(()).unwrap();
-            });
-        }
-
-        let mut i = 0;
-        while i < nthreads * nmsgs {
-            match q.pop() {
-                Empty | Inconsistent => {}
-                Data(_) => i += 1,
-            }
-        }
-        drop(tx);
-        for _ in 0..nthreads {
-            rx.recv().unwrap();
-        }
-    }
-}
diff --git a/library/std/src/sync/mpsc/mpsc_queue/tests.rs b/library/std/src/sync/mpsc/mpsc_queue/tests.rs
new file mode 100644
index 00000000000..348b83424b0
--- /dev/null
+++ b/library/std/src/sync/mpsc/mpsc_queue/tests.rs
@@ -0,0 +1,47 @@
+use super::{Data, Empty, Inconsistent, Queue};
+use crate::sync::mpsc::channel;
+use crate::sync::Arc;
+use crate::thread;
+
+#[test]
+fn test_full() {
+    let q: Queue<Box<_>> = Queue::new();
+    q.push(box 1);
+    q.push(box 2);
+}
+
+#[test]
+fn test() {
+    let nthreads = 8;
+    let nmsgs = 1000;
+    let q = Queue::new();
+    match q.pop() {
+        Empty => {}
+        Inconsistent | Data(..) => panic!(),
+    }
+    let (tx, rx) = channel();
+    let q = Arc::new(q);
+
+    for _ in 0..nthreads {
+        let tx = tx.clone();
+        let q = q.clone();
+        thread::spawn(move || {
+            for i in 0..nmsgs {
+                q.push(i);
+            }
+            tx.send(()).unwrap();
+        });
+    }
+
+    let mut i = 0;
+    while i < nthreads * nmsgs {
+        match q.pop() {
+            Empty | Inconsistent => {}
+            Data(_) => i += 1,
+        }
+    }
+    drop(tx);
+    for _ in 0..nthreads {
+        rx.recv().unwrap();
+    }
+}
diff --git a/library/std/src/sync/mpsc/spsc_queue.rs b/library/std/src/sync/mpsc/spsc_queue.rs
index 0274268f69f..9bf99f193ca 100644
--- a/library/std/src/sync/mpsc/spsc_queue.rs
+++ b/library/std/src/sync/mpsc/spsc_queue.rs
@@ -6,6 +6,9 @@
 
 // http://www.1024cores.net/home/lock-free-algorithms/queues/unbounded-spsc-queue
 
+#[cfg(all(test, not(target_os = "emscripten")))]
+mod tests;
+
 use core::cell::UnsafeCell;
 use core::ptr;
 
@@ -231,108 +234,3 @@ impl<T, ProducerAddition, ConsumerAddition> Drop for Queue<T, ProducerAddition,
         }
     }
 }
-
-#[cfg(all(test, not(target_os = "emscripten")))]
-mod tests {
-    use super::Queue;
-    use crate::sync::mpsc::channel;
-    use crate::sync::Arc;
-    use crate::thread;
-
-    #[test]
-    fn smoke() {
-        unsafe {
-            let queue = Queue::with_additions(0, (), ());
-            queue.push(1);
-            queue.push(2);
-            assert_eq!(queue.pop(), Some(1));
-            assert_eq!(queue.pop(), Some(2));
-            assert_eq!(queue.pop(), None);
-            queue.push(3);
-            queue.push(4);
-            assert_eq!(queue.pop(), Some(3));
-            assert_eq!(queue.pop(), Some(4));
-            assert_eq!(queue.pop(), None);
-        }
-    }
-
-    #[test]
-    fn peek() {
-        unsafe {
-            let queue = Queue::with_additions(0, (), ());
-            queue.push(vec![1]);
-
-            // Ensure the borrowchecker works
-            match queue.peek() {
-                Some(vec) => {
-                    assert_eq!(&*vec, &[1]);
-                }
-                None => unreachable!(),
-            }
-
-            match queue.pop() {
-                Some(vec) => {
-                    assert_eq!(&*vec, &[1]);
-                }
-                None => unreachable!(),
-            }
-        }
-    }
-
-    #[test]
-    fn drop_full() {
-        unsafe {
-            let q: Queue<Box<_>> = Queue::with_additions(0, (), ());
-            q.push(box 1);
-            q.push(box 2);
-        }
-    }
-
-    #[test]
-    fn smoke_bound() {
-        unsafe {
-            let q = Queue::with_additions(0, (), ());
-            q.push(1);
-            q.push(2);
-            assert_eq!(q.pop(), Some(1));
-            assert_eq!(q.pop(), Some(2));
-            assert_eq!(q.pop(), None);
-            q.push(3);
-            q.push(4);
-            assert_eq!(q.pop(), Some(3));
-            assert_eq!(q.pop(), Some(4));
-            assert_eq!(q.pop(), None);
-        }
-    }
-
-    #[test]
-    fn stress() {
-        unsafe {
-            stress_bound(0);
-            stress_bound(1);
-        }
-
-        unsafe fn stress_bound(bound: usize) {
-            let q = Arc::new(Queue::with_additions(bound, (), ()));
-
-            let (tx, rx) = channel();
-            let q2 = q.clone();
-            let _t = thread::spawn(move || {
-                for _ in 0..100000 {
-                    loop {
-                        match q2.pop() {
-                            Some(1) => break,
-                            Some(_) => panic!(),
-                            None => {}
-                        }
-                    }
-                }
-                tx.send(()).unwrap();
-            });
-            for _ in 0..100000 {
-                q.push(1);
-            }
-            rx.recv().unwrap();
-        }
-    }
-}
diff --git a/library/std/src/sync/mpsc/spsc_queue/tests.rs b/library/std/src/sync/mpsc/spsc_queue/tests.rs
new file mode 100644
index 00000000000..e4fd15cbbde
--- /dev/null
+++ b/library/std/src/sync/mpsc/spsc_queue/tests.rs
@@ -0,0 +1,101 @@
+use super::Queue;
+use crate::sync::mpsc::channel;
+use crate::sync::Arc;
+use crate::thread;
+
+#[test]
+fn smoke() {
+    unsafe {
+        let queue = Queue::with_additions(0, (), ());
+        queue.push(1);
+        queue.push(2);
+        assert_eq!(queue.pop(), Some(1));
+        assert_eq!(queue.pop(), Some(2));
+        assert_eq!(queue.pop(), None);
+        queue.push(3);
+        queue.push(4);
+        assert_eq!(queue.pop(), Some(3));
+        assert_eq!(queue.pop(), Some(4));
+        assert_eq!(queue.pop(), None);
+    }
+}
+
+#[test]
+fn peek() {
+    unsafe {
+        let queue = Queue::with_additions(0, (), ());
+        queue.push(vec![1]);
+
+        // Ensure the borrowchecker works
+        match queue.peek() {
+            Some(vec) => {
+                assert_eq!(&*vec, &[1]);
+            }
+            None => unreachable!(),
+        }
+
+        match queue.pop() {
+            Some(vec) => {
+                assert_eq!(&*vec, &[1]);
+            }
+            None => unreachable!(),
+        }
+    }
+}
+
+#[test]
+fn drop_full() {
+    unsafe {
+        let q: Queue<Box<_>> = Queue::with_additions(0, (), ());
+        q.push(box 1);
+        q.push(box 2);
+    }
+}
+
+#[test]
+fn smoke_bound() {
+    unsafe {
+        let q = Queue::with_additions(0, (), ());
+        q.push(1);
+        q.push(2);
+        assert_eq!(q.pop(), Some(1));
+        assert_eq!(q.pop(), Some(2));
+        assert_eq!(q.pop(), None);
+        q.push(3);
+        q.push(4);
+        assert_eq!(q.pop(), Some(3));
+        assert_eq!(q.pop(), Some(4));
+        assert_eq!(q.pop(), None);
+    }
+}
+
+#[test]
+fn stress() {
+    unsafe {
+        stress_bound(0);
+        stress_bound(1);
+    }
+
+    unsafe fn stress_bound(bound: usize) {
+        let q = Arc::new(Queue::with_additions(bound, (), ()));
+
+        let (tx, rx) = channel();
+        let q2 = q.clone();
+        let _t = thread::spawn(move || {
+            for _ in 0..100000 {
+                loop {
+                    match q2.pop() {
+                        Some(1) => break,
+                        Some(_) => panic!(),
+                        None => {}
+                    }
+                }
+            }
+            tx.send(()).unwrap();
+        });
+        for _ in 0..100000 {
+            q.push(1);
+        }
+        rx.recv().unwrap();
+    }
+}
diff --git a/library/std/src/sync/mpsc/sync_tests.rs b/library/std/src/sync/mpsc/sync_tests.rs
new file mode 100644
index 00000000000..0052a38f7bb
--- /dev/null
+++ b/library/std/src/sync/mpsc/sync_tests.rs
@@ -0,0 +1,647 @@
+use super::*;
+use crate::env;
+use crate::thread;
+use crate::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 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);
+}
+
+#[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() {}
+}
+
+#[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() {}
+}
+
+#[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);
+    thread::spawn(move || {
+        tx.send(1).unwrap();
+        tx.send(1).unwrap();
+    });
+    while rx.recv().is_ok() {}
+}
+
+#[test]
+fn stress() {
+    let (tx, rx) = sync_channel::<i32>(0);
+    thread::spawn(move || {
+        for _ in 0..10000 {
+            tx.send(1).unwrap();
+        }
+    });
+    for _ in 0..10000 {
+        assert_eq!(rx.recv().unwrap(), 1);
+    }
+}
+
+#[test]
+fn stress_recv_timeout_two_threads() {
+    let (tx, rx) = sync_channel::<i32>(0);
+
+    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);
+}
+
+#[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);
+
+    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();
+    });
+
+    for _ in 0..NTHREADS {
+        let tx = tx.clone();
+        thread::spawn(move || {
+            for _ in 0..AMT {
+                tx.send(1).unwrap();
+            }
+        });
+    }
+
+    drop(tx);
+
+    drx.recv().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);
+
+    thread::spawn(move || {
+        for _ in 0..AMT * NTHREADS {
+            assert_eq!(rx.recv().unwrap(), 1);
+        }
+        match rx.try_recv() {
+            Ok(..) => panic!(),
+            _ => {}
+        }
+        dtx.send(()).unwrap();
+    });
+
+    for _ in 0..NTHREADS {
+        let tx = tx.clone();
+        thread::spawn(move || {
+            for _ in 0..AMT {
+                tx.send(1).unwrap();
+            }
+        });
+    }
+    drop(tx);
+    drx.recv().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 0).is_err());
+}
+
+#[test]
+fn oneshot_single_thread_recv_chan_close() {
+    // Receiving on a closed chan will panic
+    let res = thread::spawn(move || {
+        let (tx, rx) = sync_channel::<i32>(0);
+        drop(tx);
+        rx.recv().unwrap();
+    })
+    .join();
+    // What is our res?
+    assert!(res.is_err());
+}
+
+#[test]
+fn oneshot_single_thread_send_then_recv() {
+    let (tx, rx) = sync_channel::<Box<i32>>(1);
+    tx.send(box 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 10).unwrap();
+}
+
+#[test]
+fn oneshot_multi_task_recv_then_close() {
+    let (tx, rx) = sync_channel::<Box<i32>>(0);
+    let _t = thread::spawn(move || {
+        drop(tx);
+    });
+    let res = thread::spawn(move || {
+        assert!(*rx.recv().unwrap() == 10);
+    })
+    .join();
+    assert!(res.is_err());
+}
+
+#[test]
+fn oneshot_multi_thread_close_stress() {
+    for _ in 0..stress_factor() {
+        let (tx, rx) = sync_channel::<i32>(0);
+        let _t = thread::spawn(move || {
+            drop(rx);
+        });
+        drop(tx);
+    }
+}
+
+#[test]
+fn oneshot_multi_thread_send_close_stress() {
+    for _ in 0..stress_factor() {
+        let (tx, rx) = sync_channel::<i32>(0);
+        let _t = thread::spawn(move || {
+            drop(rx);
+        });
+        let _ = thread::spawn(move || {
+            tx.send(1).unwrap();
+        })
+        .join();
+    }
+}
+
+#[test]
+fn oneshot_multi_thread_recv_close_stress() {
+    for _ in 0..stress_factor() {
+        let (tx, rx) = sync_channel::<i32>(0);
+        let _t = thread::spawn(move || {
+            let res = thread::spawn(move || {
+                rx.recv().unwrap();
+            })
+            .join();
+            assert!(res.is_err());
+        });
+        let _t = thread::spawn(move || {
+            thread::spawn(move || {
+                drop(tx);
+            });
+        });
+    }
+}
+
+#[test]
+fn oneshot_multi_thread_send_recv_stress() {
+    for _ in 0..stress_factor() {
+        let (tx, rx) = sync_channel::<Box<i32>>(0);
+        let _t = thread::spawn(move || {
+            tx.send(box 10).unwrap();
+        });
+        assert!(*rx.recv().unwrap() == 10);
+    }
+}
+
+#[test]
+fn stream_send_recv_stress() {
+    for _ in 0..stress_factor() {
+        let (tx, rx) = sync_channel::<Box<i32>>(0);
+
+        send(tx, 0);
+        recv(rx, 0);
+
+        fn send(tx: SyncSender<Box<i32>>, i: i32) {
+            if i == 10 {
+                return;
+            }
+
+            thread::spawn(move || {
+                tx.send(box i).unwrap();
+                send(tx, i + 1);
+            });
+        }
+
+        fn recv(rx: Receiver<Box<i32>>, i: i32) {
+            if i == 10 {
+                return;
+            }
+
+            thread::spawn(move || {
+                assert!(*rx.recv().unwrap() == i);
+                recv(rx, i + 1);
+            });
+        }
+    }
+}
+
+#[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;
+    for _ in 0..total {
+        let tx = tx.clone();
+        thread::spawn(move || {
+            tx.send(()).unwrap();
+        });
+    }
+
+    for _ in 0..total {
+        rx.recv().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);
+}
+
+#[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);
+}
+
+#[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));
+}
+
+// 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 t = tx.clone();
+    drop(tx);
+    t.send(()).unwrap();
+
+    // wait for the child thread to exit before we exit
+    rx2.recv().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(()));
+}
+
+#[test]
+fn send2() {
+    let (tx, rx) = sync_channel::<i32>(0);
+    let _t = thread::spawn(move || {
+        drop(rx);
+    });
+    assert!(tx.send(1).is_err());
+}
+
+#[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());
+}
+
+#[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 _t = thread::spawn(move || {
+        assert!(tx2.send(2).is_err());
+        done2.send(()).unwrap();
+    });
+    drop(rx);
+    donerx.recv().unwrap();
+    donerx.recv().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()
+    }
+}
diff --git a/library/std/src/sync/mpsc/tests.rs b/library/std/src/sync/mpsc/tests.rs
new file mode 100644
index 00000000000..184ce193cbe
--- /dev/null
+++ b/library/std/src/sync/mpsc/tests.rs
@@ -0,0 +1,706 @@
+use super::*;
+use crate::env;
+use crate::thread;
+use crate::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 1).unwrap();
+}
+
+#[test]
+fn drop_full_shared() {
+    let (tx, _rx) = channel::<Box<isize>>();
+    drop(tx.clone());
+    drop(tx.clone());
+    tx.send(box 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);
+}
+
+#[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() {}
+}
+
+#[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() {}
+}
+
+#[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() {}
+}
+
+#[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().expect("thread panicked");
+}
+
+#[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!(),
+            _ => {}
+        }
+    });
+
+    for _ in 0..NTHREADS {
+        let tx = tx.clone();
+        thread::spawn(move || {
+            for _ in 0..AMT {
+                tx.send(1).unwrap();
+            }
+        });
+    }
+    drop(tx);
+    t.join().ok().expect("thread panicked");
+}
+
+#[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().expect("thread panicked");
+    t2.join().ok().expect("thread panicked");
+}
+
+#[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().expect("thread panicked");
+}
+
+#[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().expect("thread panicked");
+    t2.join().ok().expect("thread panicked");
+}
+
+#[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 0).is_err());
+}
+
+#[test]
+fn oneshot_single_thread_recv_chan_close() {
+    // Receiving on a closed chan will panic
+    let res = thread::spawn(move || {
+        let (tx, rx) = channel::<i32>();
+        drop(tx);
+        rx.recv().unwrap();
+    })
+    .join();
+    // What is our res?
+    assert!(res.is_err());
+}
+
+#[test]
+fn oneshot_single_thread_send_then_recv() {
+    let (tx, rx) = channel::<Box<i32>>();
+    tx.send(box 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 10).unwrap();
+}
+
+#[test]
+fn oneshot_multi_task_recv_then_close() {
+    let (tx, rx) = channel::<Box<i32>>();
+    let _t = thread::spawn(move || {
+        drop(tx);
+    });
+    let res = thread::spawn(move || {
+        assert!(*rx.recv().unwrap() == 10);
+    })
+    .join();
+    assert!(res.is_err());
+}
+
+#[test]
+fn oneshot_multi_thread_close_stress() {
+    for _ in 0..stress_factor() {
+        let (tx, rx) = channel::<i32>();
+        let _t = thread::spawn(move || {
+            drop(rx);
+        });
+        drop(tx);
+    }
+}
+
+#[test]
+fn oneshot_multi_thread_send_close_stress() {
+    for _ in 0..stress_factor() {
+        let (tx, rx) = channel::<i32>();
+        let _t = thread::spawn(move || {
+            drop(rx);
+        });
+        let _ = thread::spawn(move || {
+            tx.send(1).unwrap();
+        })
+        .join();
+    }
+}
+
+#[test]
+fn oneshot_multi_thread_recv_close_stress() {
+    for _ in 0..stress_factor() {
+        let (tx, rx) = channel::<i32>();
+        thread::spawn(move || {
+            let res = thread::spawn(move || {
+                rx.recv().unwrap();
+            })
+            .join();
+            assert!(res.is_err());
+        });
+        let _t = thread::spawn(move || {
+            thread::spawn(move || {
+                drop(tx);
+            });
+        });
+    }
+}
+
+#[test]
+fn oneshot_multi_thread_send_recv_stress() {
+    for _ in 0..stress_factor() {
+        let (tx, rx) = channel::<Box<isize>>();
+        let _t = thread::spawn(move || {
+            tx.send(box 10).unwrap();
+        });
+        assert!(*rx.recv().unwrap() == 10);
+    }
+}
+
+#[test]
+fn stream_send_recv_stress() {
+    for _ in 0..stress_factor() {
+        let (tx, rx) = channel();
+
+        send(tx, 0);
+        recv(rx, 0);
+
+        fn send(tx: Sender<Box<i32>>, i: i32) {
+            if i == 10 {
+                return;
+            }
+
+            thread::spawn(move || {
+                tx.send(box i).unwrap();
+                send(tx, i + 1);
+            });
+        }
+
+        fn recv(rx: Receiver<Box<i32>>, i: i32) {
+            if i == 10 {
+                return;
+            }
+
+            thread::spawn(move || {
+                assert!(*rx.recv().unwrap() == i);
+                recv(rx, i + 1);
+            });
+        }
+    }
+}
+
+#[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);
+
+    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);
+}
+
+#[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;
+
+    for i in 0..stress {
+        let tx = tx.clone();
+        thread::spawn(move || {
+            thread::sleep(Duration::from_millis(i as u64 * 10));
+            tx.send(1usize).unwrap();
+        });
+    }
+
+    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);
+}
+
+#[test]
+fn very_long_recv_timeout_wont_panic() {
+    let (tx, rx) = channel::<()>();
+    let join_handle = thread::spawn(move || rx.recv_timeout(Duration::from_secs(u64::MAX)));
+    thread::sleep(Duration::from_secs(1));
+    assert!(tx.send(()).is_ok());
+    assert_eq!(join_handle.join().unwrap(), Ok(()));
+}
+
+#[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;
+    for _ in 0..total {
+        let tx = tx.clone();
+        thread::spawn(move || {
+            tx.send(()).unwrap();
+        });
+    }
+
+    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(()));
+}
+
+#[test]
+fn shared_chan_stress() {
+    let (tx, rx) = channel();
+    let total = stress_factor() + 100;
+    for _ in 0..total {
+        let tx = tx.clone();
+        thread::spawn(move || {
+            tx.send(()).unwrap();
+        });
+    }
+
+    for _ in 0..total {
+        rx.recv().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);
+}
+
+#[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);
+}
+
+#[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));
+}
+
+// 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 t = tx.clone();
+    drop(tx);
+    t.send(()).unwrap();
+
+    // wait for the child thread to exit before we exit
+    rx2.recv().unwrap();
+}
+
+#[test]
+fn issue_32114() {
+    let (tx, _) = channel();
+    let _ = tx.send(123);
+    assert_eq!(tx.send(123), Err(SendError(123)));
+}