diff -r 000000000000 -r 6474c204b198 js/src/jsapi-tests/testIntern.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jsapi-tests/testIntern.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,48 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "jsatom.h"
+
+#include "gc/Marking.h"
+#include "jsapi-tests/tests.h"
+#include "vm/String.h"
+
+using mozilla::ArrayLength;
+
+BEGIN_TEST(testAtomizedIsNotInterned)
+{
+    /* Try to pick a string that won't be interned by other tests in this runtime. */
+    static const char someChars[] = "blah blah blah? blah blah blah";
+    JS::Rooted<JSAtom*> atom(cx, js::Atomize(cx, someChars, ArrayLength(someChars)));
+    CHECK(!JS_StringHasBeenInterned(cx, atom));
+    CHECK(JS_InternJSString(cx, atom));
+    CHECK(JS_StringHasBeenInterned(cx, atom));
+    return true;
+}
+END_TEST(testAtomizedIsNotInterned)
+
+struct StringWrapperStruct
+{
+    JSString *str;
+    bool     strOk;
+} sw;
+
+BEGIN_TEST(testInternAcrossGC)
+{
+    sw.str = JS_InternString(cx, "wrapped chars that another test shouldn't be using");
+    sw.strOk = false;
+    CHECK(sw.str);
+    JS_SetFinalizeCallback(rt, FinalizeCallback);
+    JS_GC(rt);
+    CHECK(sw.strOk);
+    return true;
+}
+
+static void
+FinalizeCallback(JSFreeOp *fop, JSFinalizeStatus status, bool isCompartmentGC)
+{
+    if (status == JSFINALIZE_GROUP_START)
+        sw.strOk = js::gc::IsStringMarked(&sw.str);
+}
+END_TEST(testInternAcrossGC)