Test mpmc's current_thread_id()

Author: kornelski

library/std/src/sync/mpmc/mod.rs

@@ -1382,3 +1382,6 @@ impl<T> fmt::Debug for Receiver<T> {
         f.pad("Receiver { .. }")
     }
 }
+
+#[cfg(test)]
+mod tests;

library/std/src/sync/mpmc/tests.rs

@@ -0,0 +1,13 @@
+#[test]
+fn waker_current_thread_id() {
+    let first = super::waker::current_thread_id();
+    let t = crate::thread::spawn(|| {
+        let second = super::waker::current_thread_id();
+        assert_ne!(first, second);
+        assert_eq!(second, super::waker::current_thread_id());
+    });
+
+    assert_eq!(first, super::waker::current_thread_id());
+    t.join().unwrap();
+    assert_eq!(first, super::waker::current_thread_id());
+}