1 files changed, 78 insertions, 0 deletions
diff --git a/xpcom/rust/gtest/moz_task/test.rs b/xpcom/rust/gtest/moz_task/test.rs
new file mode 100644
index 0000000000..fa4c0af852
--- /dev/null
+++ b/xpcom/rust/gtest/moz_task/test.rs
@@ -0,0 +1,78 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use moz_task;
+use std::{
+    future::Future,
+    pin::Pin,
+    task::{Context, Poll, Waker},
+};
+
+/// Demo `Future` to demonstrate executing futures to completion via `nsIEventTarget`.
+struct MyFuture {
+    poll_count: u32,
+    waker: Option<Waker>,
+    expect_main_thread: bool,
+}
+
+impl MyFuture {
+    fn new(expect_main_thread: bool) -> Self {
+        Self {
+            poll_count: 0,
+            waker: None,
+            expect_main_thread,
+        }
+    }
+}
+
+impl Future for MyFuture {
+    type Output = u32;
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<u32> {
+        assert_eq!(moz_task::is_main_thread(), self.expect_main_thread);
+
+        self.poll_count += 1;
+
+        if let Some(waker) = &mut self.waker {
+            if !waker.will_wake(cx.waker()) {
+                *waker = cx.waker().clone();
+            }
+        } else {
+            let waker = cx.waker().clone();
+            self.waker = Some(waker);
+        }
+
+        println!("Poll count = {}", self.poll_count);
+        if self.poll_count > 5 {
+            Poll::Ready(self.poll_count)
+        } else {
+            // Just notify the task that we need to re-polled.
+            if let Some(waker) = &self.waker {
+                waker.wake_by_ref();
+            }
+            Poll::Pending
+        }
+    }
+}
+
+#[no_mangle]
+pub extern "C" fn Rust_Future(it_worked: *mut bool) {
+    let future = async move {
+        assert_eq!(MyFuture::new(true).await, 6);
+        assert_eq!(
+            moz_task::spawn_local("Rust_Future inner spawn_local", MyFuture::new(true)).await,
+            6
+        );
+        assert_eq!(
+            moz_task::spawn("Rust_Future inner spawn", MyFuture::new(false)).await,
+            6
+        );
+        unsafe {
+            *it_worked = true;
+        }
+    };
+    unsafe {
+        moz_task::gtest_only::spin_event_loop_until("Rust_Future", future).unwrap();
+    };
+}