can_refer_to_singular

src/rstd/collections/tree.rs

@@ -279,4 +279,12 @@ mod tests {
         let tree = trees.clone().add_tree(tree, 0.into()).unwrap();
         assert_eq!(trees.height(&tree), 1);
     }
+
+    #[test]
+    fn can_refer_to_singular() {
+        let trees = BalancedTrees::new(new_trees());
+        let tree = trees.empty();
+        let tree = trees.clone().add_tree(tree, 0.into()).unwrap();
+        assert!(trees.refer(&tree).is_some());
+    }
 }