Add MappedRwLock*Guard tests.

Author: zachs18

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

@@ -1,6 +1,6 @@
 use crate::sync::atomic::{AtomicUsize, Ordering};
 use crate::sync::mpsc::channel;
-use crate::sync::{Arc, RwLock, RwLockReadGuard, TryLockError};
+use crate::sync::{Arc, RwLock, RwLockReadGuard, RwLockWriteGuard, MappedRwLockReadGuard, MappedRwLockWriteGuard, TryLockError};
 use crate::thread;
 use rand::Rng;
 
@@ -55,6 +55,19 @@ fn test_rw_arc_poison_wr() {
     assert!(arc.read().is_err());
 }
 
+#[test]
+fn test_rw_arc_poison_mapped_w_r() {
+    let arc = Arc::new(RwLock::new(1));
+    let arc2 = arc.clone();
+    let _: Result<(), _> = thread::spawn(move || {
+        let lock = arc2.write().unwrap();
+        let _lock = RwLockWriteGuard::map(lock, |val| val);
+        panic!();
+    })
+    .join();
+    assert!(arc.read().is_err());
+}
+
 #[test]
 fn test_rw_arc_poison_ww() {
     let arc = Arc::new(RwLock::new(1));
@@ -69,6 +82,20 @@ fn test_rw_arc_poison_ww() {
     assert!(arc.is_poisoned());
 }
 
+#[test]
+fn test_rw_arc_poison_mapped_w_w() {
+    let arc = Arc::new(RwLock::new(1));
+    let arc2 = arc.clone();
+    let _: Result<(), _> = thread::spawn(move || {
+        let lock = arc2.write().unwrap();
+        let _lock = RwLockWriteGuard::map(lock, |val| val);
+        panic!();
+    })
+    .join();
+    assert!(arc.write().is_err());
+    assert!(arc.is_poisoned());
+}
+
 #[test]
 fn test_rw_arc_no_poison_rr() {
     let arc = Arc::new(RwLock::new(1));
@@ -81,6 +108,21 @@ fn test_rw_arc_no_poison_rr() {
     let lock = arc.read().unwrap();
     assert_eq!(*lock, 1);
 }
+
+#[test]
+fn test_rw_arc_no_poison_mapped_r_r() {
+    let arc = Arc::new(RwLock::new(1));
+    let arc2 = arc.clone();
+    let _: Result<(), _> = thread::spawn(move || {
+        let lock = arc2.read().unwrap();
+        let _lock = RwLockReadGuard::map(lock, |val| val);
+        panic!();
+    })
+    .join();
+    let lock = arc.read().unwrap();
+    assert_eq!(*lock, 1);
+}
+
 #[test]
 fn test_rw_arc_no_poison_rw() {
     let arc = Arc::new(RwLock::new(1));
@@ -94,6 +136,20 @@ fn test_rw_arc_no_poison_rw() {
     assert_eq!(*lock, 1);
 }
 
+#[test]
+fn test_rw_arc_no_poison_mapped_r_w() {
+    let arc = Arc::new(RwLock::new(1));
+    let arc2 = arc.clone();
+    let _: Result<(), _> = thread::spawn(move || {
+        let lock = arc2.read().unwrap();
+        let _lock = RwLockReadGuard::map(lock, |val| val);
+        panic!();
+    })
+    .join();
+    let lock = arc.write().unwrap();
+    assert_eq!(*lock, 1);
+}
+
 #[test]
 fn test_rw_arc() {
     let arc = Arc::new(RwLock::new(0));
@@ -179,6 +235,16 @@ fn test_rwlock_try_write() {
     }
 
     drop(read_guard);
+    let mapped_read_guard = RwLockReadGuard::map(lock.read().unwrap(), |_| &());
+
+    let write_result = lock.try_write();
+    match write_result {
+        Err(TryLockError::WouldBlock) => (),
+        Ok(_) => assert!(false, "try_write should not succeed while mapped_read_guard is in scope"),
+        Err(_) => assert!(false, "unexpected error"),
+    }
+
+    drop(mapped_read_guard);
 }
 
 #[test]
@@ -257,3 +323,37 @@ fn test_read_guard_covariance() {
     }
     drop(lock);
 }
+
+#[test]
+fn test_mapped_read_guard_covariance() {
+    fn do_stuff<'a>(_: MappedRwLockReadGuard<'_, &'a i32>, _: &'a i32) {}
+    let j: i32 = 5;
+    let lock = RwLock::new((&j, &j));
+    {
+        let i = 6;
+        let guard = lock.read().unwrap();
+        let guard = RwLockReadGuard::map(guard, |(val, _val)| val);
+        do_stuff(guard, &i);
+    }
+    drop(lock);
+}
+
+#[test]
+fn test_mapping_mapped_guard() {
+    let arr = [0; 4];
+    let mut lock = RwLock::new(arr);
+    let guard = lock.write().unwrap();
+    let guard = RwLockWriteGuard::map(guard, |arr| &mut arr[..2]);
+    let mut guard = MappedRwLockWriteGuard::map(guard, |slice| &mut slice[1..]);
+    assert_eq!(guard.len(), 1);
+    guard[0] = 42;
+    drop(guard);
+    assert_eq!(*lock.get_mut().unwrap(), [0, 42, 0, 0]);
+
+    let guard = lock.read().unwrap();
+    let guard = RwLockReadGuard::map(guard, |arr| &arr[..2]);
+    let guard = MappedRwLockReadGuard::map(guard, |slice| &slice[1..]);
+    assert_eq!(*guard, [42]);
+    drop(guard);
+    assert_eq!(*lock.get_mut().unwrap(), [0, 42, 0, 0]);
+}