1 files changed, 10 insertions, 0 deletions
diff --git a/js/xpconnect/tests/unit/test_bug856067.js b/js/xpconnect/tests/unit/test_bug856067.js
new file mode 100644
index 000000000..b23cd45fb
--- /dev/null
+++ b/js/xpconnect/tests/unit/test_bug856067.js
@@ -0,0 +1,10 @@
+const Cu = Components.utils;
+
+function run_test() {
+  var sb = new Cu.Sandbox('http://www.example.com');
+  let w = Cu.evalInSandbox('var w = new WeakMap(); w.__proto__ = new Set(); w.foopy = 12; w', sb);
+  do_check_eq(Object.getPrototypeOf(w), sb.Object.prototype);
+  do_check_eq(Object.getOwnPropertyNames(w).length, 0);
+  do_check_eq(w.wrappedJSObject.foopy, 12);
+  do_check_eq(w.foopy, undefined);
+}