Add unit tests for new BTreeMap::into_{keys,values} methods

library/alloc/tests/btree/map.rs

@@ -1461,3 +1461,27 @@ fn test_into_iter_drop_leak_height_1() {
         assert_eq!(DROPS.load(Ordering::SeqCst), size);
     }
 }
+
+#[test]
+fn test_into_keys() {
+    let vec = vec![(1, 'a'), (2, 'b'), (3, 'c')];
+    let map: BTreeMap<_, _> = vec.into_iter().collect();
+    let keys: Vec<_> = map.into_keys().collect();
+
+    assert_eq!(keys.len(), 3);
+    assert!(keys.contains(&1));
+    assert!(keys.contains(&2));
+    assert!(keys.contains(&3));
+}
+
+#[test]
+fn test_into_values() {
+    let vec = vec![(1, 'a'), (2, 'b'), (3, 'c')];
+    let map: BTreeMap<_, _> = vec.into_iter().collect();
+    let values: Vec<_> = map.into_values().collect();
+
+    assert_eq!(values.len(), 3);
+    assert!(values.contains(&'a'));
+    assert!(values.contains(&'b'));
+    assert!(values.contains(&'c'));
+}

library/alloc/tests/lib.rs

@@ -4,6 +4,7 @@
 #![feature(drain_filter)]
 #![feature(exact_size_is_empty)]
 #![feature(map_first_last)]
+#![feature(map_into_keys_values)]
 #![feature(new_uninit)]
 #![feature(pattern)]
 #![feature(str_split_once)]