diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/collections/Set-clear-2.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/collections/Set-clear-2.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,16 @@
+// Clearing a Set removes its elements; the Set remains usable afterwards.
+
+var s = Set(["x", "y", "z", "z", "y"]);
+assertEq(s.size, 3);
+s.clear();
+assertEq(s.size, 0);
+assertEq(s.has("x"), false);
+assertEq(s.delete("x"), false);
+assertEq(s.has("z"), false);
+for (var v of s)
+    throw "FAIL";  // shouldn't be any elements
+
+s.add("y");
+assertEq(s.size, 1);
+assertEq(s.has("x"), false);
+assertEq(s.has("z"), false);