add tests for oneshot

This commit adds tests for the very basic new oneshot module. Most of
the tests were taken/heavily inspired by tests from the `oneshot crate.

Author: connortsui20

library/std/tests/sync/lib.rs

@@ -1,6 +1,7 @@
 #![feature(lazy_get)]
 #![feature(mapped_lock_guards)]
 #![feature(mpmc_channel)]
+#![feature(oneshot_channel)]
 #![feature(once_cell_try)]
 #![feature(lock_value_accessors)]
 #![feature(reentrant_lock)]
@@ -23,6 +24,8 @@ mod mutex;
 mod once;
 mod once_lock;
 #[cfg(not(any(target_os = "emscripten", target_os = "wasi")))]
+mod oneshot;
+#[cfg(not(any(target_os = "emscripten", target_os = "wasi")))]
 mod reentrant_lock;
 #[cfg(not(any(target_os = "emscripten", target_os = "wasi")))]
 mod rwlock;

library/std/tests/sync/oneshot.rs

@@ -0,0 +1,342 @@
+//! Inspired by tests from <https://github.com/faern/oneshot/blob/main/tests/sync.rs>
+
+use std::sync::mpsc::RecvError;
+use std::sync::oneshot;
+use std::sync::oneshot::{RecvTimeoutError, TryRecvError};
+use std::time::{Duration, Instant};
+use std::{mem, thread};
+
+#[test]
+fn send_before_try_recv() {
+    let (sender, receiver) = oneshot::channel();
+
+    assert!(sender.send(19i128).is_ok());
+
+    match receiver.try_recv() {
+        Ok(19) => {}
+        _ => panic!("expected Ok(19)"),
+    }
+}
+
+#[test]
+fn send_before_recv() {
+    let (sender, receiver) = oneshot::channel::<()>();
+
+    assert!(sender.send(()).is_ok());
+    assert_eq!(receiver.recv(), Ok(()));
+
+    let (sender, receiver) = oneshot::channel::<u64>();
+
+    assert!(sender.send(42).is_ok());
+    assert_eq!(receiver.recv(), Ok(42));
+
+    let (sender, receiver) = oneshot::channel::<[u8; 4096]>();
+
+    assert!(sender.send([0b10101010; 4096]).is_ok());
+    assert!(receiver.recv().unwrap()[..] == [0b10101010; 4096][..]);
+}
+
+#[test]
+fn sender_drop() {
+    {
+        let (sender, receiver) = oneshot::channel::<u128>();
+
+        mem::drop(sender);
+
+        match receiver.recv() {
+            Err(RecvError) => {}
+            _ => panic!("expected recv error"),
+        }
+    }
+
+    {
+        let (sender, receiver) = oneshot::channel::<i32>();
+
+        mem::drop(sender);
+
+        match receiver.try_recv() {
+            Err(TryRecvError::Disconnected) => {}
+            _ => panic!("expected disconnected error"),
+        }
+    }
+    {
+        let (sender, receiver) = oneshot::channel::<i32>();
+
+        mem::drop(sender);
+
+        match receiver.recv_timeout(Duration::from_secs(1)) {
+            Err(RecvTimeoutError::Disconnected) => {}
+            _ => panic!("expected disconnected error"),
+        }
+    }
+}
+
+#[test]
+fn send_never_deadline() {
+    let (sender, receiver) = oneshot::channel::<i32>();
+
+    mem::drop(sender);
+
+    match receiver.recv_deadline(Instant::now()) {
+        Err(RecvTimeoutError::Disconnected) => {}
+        _ => panic!("expected disconnected error"),
+    }
+}
+
+#[test]
+fn send_before_recv_timeout() {
+    let (sender, receiver) = oneshot::channel();
+
+    assert!(sender.send(22i128).is_ok());
+
+    let start = Instant::now();
+
+    let timeout = Duration::from_secs(1);
+    match receiver.recv_timeout(timeout) {
+        Ok(22) => {}
+        _ => panic!("expected Ok(22)"),
+    }
+
+    assert!(start.elapsed() < timeout);
+}
+
+#[test]
+fn send_error() {
+    let (sender, receiver) = oneshot::channel();
+
+    mem::drop(receiver);
+
+    let send_error = sender.send(32u128).unwrap_err();
+    assert_eq!(send_error.0, 32);
+}
+
+#[test]
+fn recv_before_send() {
+    let (sender, receiver) = oneshot::channel();
+
+    let t1 = thread::spawn(move || {
+        thread::sleep(Duration::from_millis(10));
+        sender.send(9u128).unwrap();
+    });
+    let t2 = thread::spawn(move || {
+        assert_eq!(receiver.recv(), Ok(9));
+    });
+
+    t1.join().unwrap();
+    t2.join().unwrap();
+}
+
+#[test]
+fn recv_timeout_before_send() {
+    let (sender, receiver) = oneshot::channel();
+
+    let t = thread::spawn(move || {
+        thread::sleep(Duration::from_millis(100));
+        sender.send(99u128).unwrap();
+    });
+
+    match receiver.recv_timeout(Duration::from_secs(1)) {
+        Ok(99) => {}
+        _ => panic!("expected Ok(99)"),
+    }
+
+    t.join().unwrap();
+}
+
+#[test]
+fn recv_then_drop_sender() {
+    let (sender, receiver) = oneshot::channel::<u128>();
+
+    let t1 = thread::spawn(move || match receiver.recv() {
+        Err(RecvError) => {}
+        _ => panic!("expected recv error"),
+    });
+
+    let t2 = thread::spawn(move || {
+        thread::sleep(Duration::from_millis(10));
+        mem::drop(sender);
+    });
+
+    t1.join().unwrap();
+    t2.join().unwrap();
+}
+
+#[test]
+fn drop_sender_then_recv() {
+    let (sender, receiver) = oneshot::channel::<u128>();
+
+    let t1 = thread::spawn(move || {
+        thread::sleep(Duration::from_millis(10));
+        mem::drop(sender);
+    });
+
+    let t2 = thread::spawn(move || match receiver.recv() {
+        Err(RecvError) => {}
+        _ => panic!("expected disconnected error"),
+    });
+
+    t1.join().unwrap();
+    t2.join().unwrap();
+}
+
+#[test]
+fn try_recv_empty() {
+    let (sender, receiver) = oneshot::channel::<u128>();
+    match receiver.try_recv() {
+        Err(TryRecvError::Empty(_)) => {}
+        _ => panic!("expected empty error"),
+    }
+    mem::drop(sender);
+}
+
+#[test]
+fn try_recv_then_drop_receiver() {
+    let (sender, receiver) = oneshot::channel::<u128>();
+
+    let t1 = thread::spawn(move || {
+        thread::sleep(Duration::from_millis(100));
+        let _ = sender.send(42);
+    });
+
+    let t2 = thread::spawn(move || match receiver.try_recv() {
+        Ok(_) => {}
+        Err(TryRecvError::Empty(r)) => {
+            mem::drop(r);
+        }
+        Err(TryRecvError::Disconnected) => {}
+    });
+
+    t2.join().unwrap();
+    t1.join().unwrap();
+}
+
+#[test]
+fn recv_no_time() {
+    let (_sender, receiver) = oneshot::channel::<u128>();
+
+    let start = Instant::now();
+    match receiver.recv_deadline(start) {
+        Err(RecvTimeoutError::Timeout(_)) => {}
+        _ => panic!("expected timeout error"),
+    }
+
+    let (_sender, receiver) = oneshot::channel::<u128>();
+    match receiver.recv_timeout(Duration::from_millis(0)) {
+        Err(RecvTimeoutError::Timeout(_)) => {}
+        _ => panic!("expected timeout error"),
+    }
+}
+
+#[test]
+fn recv_deadline_passed() {
+    let (_sender, receiver) = oneshot::channel::<u128>();
+
+    let start = Instant::now();
+    let timeout = Duration::from_millis(100);
+
+    match receiver.recv_deadline(start + timeout) {
+        Err(RecvTimeoutError::Timeout(_)) => {}
+        _ => panic!("expected timeout error"),
+    }
+
+    assert!(start.elapsed() >= timeout);
+    assert!(start.elapsed() < timeout * 3);
+}
+
+#[test]
+fn recv_time_passed() {
+    let (_sender, receiver) = oneshot::channel::<u128>();
+
+    let start = Instant::now();
+    let timeout = Duration::from_millis(100);
+    match receiver.recv_timeout(timeout) {
+        Err(RecvTimeoutError::Timeout(_)) => {}
+        _ => panic!("expected timeout error"),
+    }
+    assert!(start.elapsed() >= timeout);
+    assert!(start.elapsed() < timeout * 3);
+}
+
+#[test]
+fn non_send_type_can_be_used_on_same_thread() {
+    use std::ptr;
+
+    #[derive(Debug, Eq, PartialEq)]
+    struct NotSend(*mut ());
+
+    let (sender, receiver) = oneshot::channel();
+    sender.send(NotSend(ptr::null_mut())).unwrap();
+    let reply = receiver.try_recv().unwrap();
+    assert_eq!(reply, NotSend(ptr::null_mut()));
+}
+
+/// Helper for testing drop behavior (taken directly from the `oneshot` crate).
+struct DropCounter {
+    count: std::rc::Rc<std::cell::RefCell<usize>>,
+}
+
+impl DropCounter {
+    fn new() -> (DropTracker, DropCounter) {
+        let count = std::rc::Rc::new(std::cell::RefCell::new(0));
+        (DropTracker { count: count.clone() }, DropCounter { count })
+    }
+
+    fn count(&self) -> usize {
+        *self.count.borrow()
+    }
+}
+
+struct DropTracker {
+    count: std::rc::Rc<std::cell::RefCell<usize>>,
+}
+
+impl Drop for DropTracker {
+    fn drop(&mut self) {
+        *self.count.borrow_mut() += 1;
+    }
+}
+
+#[test]
+fn message_in_channel_dropped_on_receiver_drop() {
+    let (sender, receiver) = oneshot::channel();
+
+    let (message, counter) = DropCounter::new();
+    assert_eq!(counter.count(), 0);
+
+    sender.send(message).unwrap();
+    assert_eq!(counter.count(), 0);
+
+    mem::drop(receiver);
+    assert_eq!(counter.count(), 1);
+}
+
+#[test]
+fn send_error_drops_message_correctly() {
+    let (sender, receiver) = oneshot::channel();
+    mem::drop(receiver);
+
+    let (message, counter) = DropCounter::new();
+
+    let send_error = sender.send(message).unwrap_err();
+    assert_eq!(counter.count(), 0);
+
+    mem::drop(send_error);
+    assert_eq!(counter.count(), 1);
+}
+
+#[test]
+fn send_error_drops_message_correctly_on_extract() {
+    let (sender, receiver) = oneshot::channel();
+    mem::drop(receiver);
+
+    let (message, counter) = DropCounter::new();
+
+    let send_error = sender.send(message).unwrap_err();
+    assert_eq!(counter.count(), 0);
+
+    let message = send_error.0; // Access the inner value directly
+    assert_eq!(counter.count(), 0);
+
+    mem::drop(message);
+    assert_eq!(counter.count(), 1);
+}