1 files changed, 213 insertions, 0 deletions
diff --git a/third_party/rust/tokio/tests/sync_watch.rs b/third_party/rust/tokio/tests/sync_watch.rs
new file mode 100644
index 0000000000..8b9ea81bb8
--- /dev/null
+++ b/third_party/rust/tokio/tests/sync_watch.rs
@@ -0,0 +1,213 @@
+#![allow(clippy::cognitive_complexity)]
+#![warn(rust_2018_idioms)]
+#![cfg(feature = "sync")]
+
+#[cfg(target_arch = "wasm32")]
+use wasm_bindgen_test::wasm_bindgen_test as test;
+
+use tokio::sync::watch;
+use tokio_test::task::spawn;
+use tokio_test::{assert_pending, assert_ready, assert_ready_err, assert_ready_ok};
+
+#[test]
+fn single_rx_recv() {
+    let (tx, mut rx) = watch::channel("one");
+
+    {
+        // Not initially notified
+        let mut t = spawn(rx.changed());
+        assert_pending!(t.poll());
+    }
+    assert_eq!(*rx.borrow(), "one");
+
+    {
+        let mut t = spawn(rx.changed());
+        assert_pending!(t.poll());
+
+        tx.send("two").unwrap();
+
+        assert!(t.is_woken());
+
+        assert_ready_ok!(t.poll());
+    }
+    assert_eq!(*rx.borrow(), "two");
+
+    {
+        let mut t = spawn(rx.changed());
+        assert_pending!(t.poll());
+
+        drop(tx);
+
+        assert!(t.is_woken());
+        assert_ready_err!(t.poll());
+    }
+    assert_eq!(*rx.borrow(), "two");
+}
+
+#[test]
+fn multi_rx() {
+    let (tx, mut rx1) = watch::channel("one");
+    let mut rx2 = rx1.clone();
+
+    {
+        let mut t1 = spawn(rx1.changed());
+        let mut t2 = spawn(rx2.changed());
+
+        assert_pending!(t1.poll());
+        assert_pending!(t2.poll());
+    }
+    assert_eq!(*rx1.borrow(), "one");
+    assert_eq!(*rx2.borrow(), "one");
+
+    let mut t2 = spawn(rx2.changed());
+
+    {
+        let mut t1 = spawn(rx1.changed());
+
+        assert_pending!(t1.poll());
+        assert_pending!(t2.poll());
+
+        tx.send("two").unwrap();
+
+        assert!(t1.is_woken());
+        assert!(t2.is_woken());
+
+        assert_ready_ok!(t1.poll());
+    }
+    assert_eq!(*rx1.borrow(), "two");
+
+    {
+        let mut t1 = spawn(rx1.changed());
+
+        assert_pending!(t1.poll());
+
+        tx.send("three").unwrap();
+
+        assert!(t1.is_woken());
+        assert!(t2.is_woken());
+
+        assert_ready_ok!(t1.poll());
+        assert_ready_ok!(t2.poll());
+    }
+    assert_eq!(*rx1.borrow(), "three");
+
+    drop(t2);
+
+    assert_eq!(*rx2.borrow(), "three");
+
+    {
+        let mut t1 = spawn(rx1.changed());
+        let mut t2 = spawn(rx2.changed());
+
+        assert_pending!(t1.poll());
+        assert_pending!(t2.poll());
+
+        tx.send("four").unwrap();
+
+        assert_ready_ok!(t1.poll());
+        assert_ready_ok!(t2.poll());
+    }
+    assert_eq!(*rx1.borrow(), "four");
+    assert_eq!(*rx2.borrow(), "four");
+}
+
+#[test]
+fn rx_observes_final_value() {
+    // Initial value
+
+    let (tx, mut rx) = watch::channel("one");
+    drop(tx);
+
+    {
+        let mut t1 = spawn(rx.changed());
+        assert_ready_err!(t1.poll());
+    }
+    assert_eq!(*rx.borrow(), "one");
+
+    // Sending a value
+
+    let (tx, mut rx) = watch::channel("one");
+
+    tx.send("two").unwrap();
+
+    {
+        let mut t1 = spawn(rx.changed());
+        assert_ready_ok!(t1.poll());
+    }
+    assert_eq!(*rx.borrow(), "two");
+
+    {
+        let mut t1 = spawn(rx.changed());
+        assert_pending!(t1.poll());
+
+        tx.send("three").unwrap();
+        drop(tx);
+
+        assert!(t1.is_woken());
+
+        assert_ready_ok!(t1.poll());
+    }
+    assert_eq!(*rx.borrow(), "three");
+
+    {
+        let mut t1 = spawn(rx.changed());
+        assert_ready_err!(t1.poll());
+    }
+    assert_eq!(*rx.borrow(), "three");
+}
+
+#[test]
+fn poll_close() {
+    let (tx, rx) = watch::channel("one");
+
+    {
+        let mut t = spawn(tx.closed());
+        assert_pending!(t.poll());
+
+        drop(rx);
+
+        assert!(t.is_woken());
+        assert_ready!(t.poll());
+    }
+
+    assert!(tx.send("two").is_err());
+}
+
+#[test]
+fn borrow_and_update() {
+    let (tx, mut rx) = watch::channel("one");
+
+    assert!(!rx.has_changed().unwrap());
+
+    tx.send("two").unwrap();
+    assert!(rx.has_changed().unwrap());
+    assert_ready!(spawn(rx.changed()).poll()).unwrap();
+    assert_pending!(spawn(rx.changed()).poll());
+    assert!(!rx.has_changed().unwrap());
+
+    tx.send("three").unwrap();
+    assert!(rx.has_changed().unwrap());
+    assert_eq!(*rx.borrow_and_update(), "three");
+    assert_pending!(spawn(rx.changed()).poll());
+    assert!(!rx.has_changed().unwrap());
+
+    drop(tx);
+    assert_eq!(*rx.borrow_and_update(), "three");
+    assert_ready!(spawn(rx.changed()).poll()).unwrap_err();
+    assert!(rx.has_changed().is_err());
+}
+
+#[test]
+fn reopened_after_subscribe() {
+    let (tx, rx) = watch::channel("one");
+    assert!(!tx.is_closed());
+
+    drop(rx);
+    assert!(tx.is_closed());
+
+    let rx = tx.subscribe();
+    assert!(!tx.is_closed());
+
+    drop(rx);
+    assert!(tx.is_closed());
+}