2 files changed, 16 insertions, 0 deletions
diff --git a/src/libcollectionstest/btree/map.rs b/src/libcollectionstest/btree/map.rs
index a27c2847a98..619bc189e6c 100644
--- a/src/libcollectionstest/btree/map.rs
+++ b/src/libcollectionstest/btree/map.rs
@@ -115,6 +115,21 @@ fn test_iter_rev() {
 }
 
 #[test]
+fn test_values_mut() {
+    let mut a = BTreeMap::new();
+    a.insert(1, String::from("hello"));
+    a.insert(2, String::from("goodbye"));
+
+    for value in a.values_mut() {
+        value.push_str("!");
+    }
+
+    let values: Vec<String> = a.values().cloned().collect();
+    assert_eq!(values, [String::from("hello!"),
+                        String::from("goodbye!")]);
+}
+
+#[test]
 fn test_iter_mixed() {
     let size = 10000;
 
diff --git a/src/libcollectionstest/lib.rs b/src/libcollectionstest/lib.rs
index 62fefaa10f6..045ac1ce977 100644
--- a/src/libcollectionstest/lib.rs
+++ b/src/libcollectionstest/lib.rs
@@ -22,6 +22,7 @@
 #![feature(enumset)]
 #![feature(iter_arith)]
 #![feature(map_entry_keys)]
+#![feature(map_values_mut)]
 #![feature(pattern)]
 #![feature(rand)]
 #![feature(set_recovery)]