1 files changed, 203 insertions, 0 deletions
diff --git a/library/std/src/sync/once_lock/tests.rs b/library/std/src/sync/once_lock/tests.rs
new file mode 100644
index 000000000..46695225b
--- /dev/null
+++ b/library/std/src/sync/once_lock/tests.rs
@@ -0,0 +1,203 @@
+use crate::{
+    panic,
+    sync::OnceLock,
+    sync::{
+        atomic::{AtomicUsize, Ordering::SeqCst},
+        mpsc::channel,
+    },
+    thread,
+};
+
+fn spawn_and_wait<R: Send + 'static>(f: impl FnOnce() -> R + Send + 'static) -> R {
+    thread::spawn(f).join().unwrap()
+}
+
+#[test]
+#[cfg_attr(target_os = "emscripten", ignore)]
+fn sync_once_cell() {
+    static ONCE_CELL: OnceLock<i32> = OnceLock::new();
+
+    assert!(ONCE_CELL.get().is_none());
+
+    spawn_and_wait(|| {
+        ONCE_CELL.get_or_init(|| 92);
+        assert_eq!(ONCE_CELL.get(), Some(&92));
+    });
+
+    ONCE_CELL.get_or_init(|| panic!("Kabom!"));
+    assert_eq!(ONCE_CELL.get(), Some(&92));
+}
+
+#[test]
+fn sync_once_cell_get_mut() {
+    let mut c = OnceLock::new();
+    assert!(c.get_mut().is_none());
+    c.set(90).unwrap();
+    *c.get_mut().unwrap() += 2;
+    assert_eq!(c.get_mut(), Some(&mut 92));
+}
+
+#[test]
+fn sync_once_cell_get_unchecked() {
+    let c = OnceLock::new();
+    c.set(92).unwrap();
+    unsafe {
+        assert_eq!(c.get_unchecked(), &92);
+    }
+}
+
+#[test]
+#[cfg_attr(target_os = "emscripten", ignore)]
+fn sync_once_cell_drop() {
+    static DROP_CNT: AtomicUsize = AtomicUsize::new(0);
+    struct Dropper;
+    impl Drop for Dropper {
+        fn drop(&mut self) {
+            DROP_CNT.fetch_add(1, SeqCst);
+        }
+    }
+
+    let x = OnceLock::new();
+    spawn_and_wait(move || {
+        x.get_or_init(|| Dropper);
+        assert_eq!(DROP_CNT.load(SeqCst), 0);
+        drop(x);
+    });
+
+    assert_eq!(DROP_CNT.load(SeqCst), 1);
+}
+
+#[test]
+fn sync_once_cell_drop_empty() {
+    let x = OnceLock::<String>::new();
+    drop(x);
+}
+
+#[test]
+fn clone() {
+    let s = OnceLock::new();
+    let c = s.clone();
+    assert!(c.get().is_none());
+
+    s.set("hello".to_string()).unwrap();
+    let c = s.clone();
+    assert_eq!(c.get().map(String::as_str), Some("hello"));
+}
+
+#[test]
+fn get_or_try_init() {
+    let cell: OnceLock<String> = OnceLock::new();
+    assert!(cell.get().is_none());
+
+    let res = panic::catch_unwind(|| cell.get_or_try_init(|| -> Result<_, ()> { panic!() }));
+    assert!(res.is_err());
+    assert!(!cell.is_initialized());
+    assert!(cell.get().is_none());
+
+    assert_eq!(cell.get_or_try_init(|| Err(())), Err(()));
+
+    assert_eq!(cell.get_or_try_init(|| Ok::<_, ()>("hello".to_string())), Ok(&"hello".to_string()));
+    assert_eq!(cell.get(), Some(&"hello".to_string()));
+}
+
+#[test]
+fn from_impl() {
+    assert_eq!(OnceLock::from("value").get(), Some(&"value"));
+    assert_ne!(OnceLock::from("foo").get(), Some(&"bar"));
+}
+
+#[test]
+fn partialeq_impl() {
+    assert!(OnceLock::from("value") == OnceLock::from("value"));
+    assert!(OnceLock::from("foo") != OnceLock::from("bar"));
+
+    assert!(OnceLock::<String>::new() == OnceLock::new());
+    assert!(OnceLock::<String>::new() != OnceLock::from("value".to_owned()));
+}
+
+#[test]
+fn into_inner() {
+    let cell: OnceLock<String> = OnceLock::new();
+    assert_eq!(cell.into_inner(), None);
+    let cell = OnceLock::new();
+    cell.set("hello".to_string()).unwrap();
+    assert_eq!(cell.into_inner(), Some("hello".to_string()));
+}
+
+#[test]
+fn is_sync_send() {
+    fn assert_traits<T: Send + Sync>() {}
+    assert_traits::<OnceLock<String>>();
+}
+
+#[test]
+fn eval_once_macro() {
+    macro_rules! eval_once {
+        (|| -> $ty:ty {
+            $($body:tt)*
+        }) => {{
+            static ONCE_CELL: OnceLock<$ty> = OnceLock::new();
+            fn init() -> $ty {
+                $($body)*
+            }
+            ONCE_CELL.get_or_init(init)
+        }};
+    }
+
+    let fib: &'static Vec<i32> = eval_once! {
+        || -> Vec<i32> {
+            let mut res = vec![1, 1];
+            for i in 0..10 {
+                let next = res[i] + res[i + 1];
+                res.push(next);
+            }
+            res
+        }
+    };
+    assert_eq!(fib[5], 8)
+}
+
+#[test]
+#[cfg_attr(target_os = "emscripten", ignore)]
+fn sync_once_cell_does_not_leak_partially_constructed_boxes() {
+    static ONCE_CELL: OnceLock<String> = OnceLock::new();
+
+    let n_readers = 10;
+    let n_writers = 3;
+    const MSG: &str = "Hello, World";
+
+    let (tx, rx) = channel();
+
+    for _ in 0..n_readers {
+        let tx = tx.clone();
+        thread::spawn(move || {
+            loop {
+                if let Some(msg) = ONCE_CELL.get() {
+                    tx.send(msg).unwrap();
+                    break;
+                }
+                #[cfg(target_env = "sgx")]
+                crate::thread::yield_now();
+            }
+        });
+    }
+    for _ in 0..n_writers {
+        thread::spawn(move || {
+            let _ = ONCE_CELL.set(MSG.to_owned());
+        });
+    }
+
+    for _ in 0..n_readers {
+        let msg = rx.recv().unwrap();
+        assert_eq!(msg, MSG);
+    }
+}
+
+#[test]
+fn dropck() {
+    let cell = OnceLock::new();
+    {
+        let s = String::new();
+        cell.set(&s).unwrap();
+    }
+}