diff -r 000000000000 -r 6474c204b198 js/src/jsapi-tests/testGCFinalizeCallback.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jsapi-tests/testGCFinalizeCallback.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,173 @@
+/* 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 "jsapi-tests/tests.h"
+
+static const unsigned BufferSize = 20;
+static unsigned FinalizeCalls = 0;
+static JSFinalizeStatus StatusBuffer[BufferSize];
+static bool IsCompartmentGCBuffer[BufferSize];
+
+BEGIN_TEST(testGCFinalizeCallback)
+{
+    JS_SetGCParameter(rt, JSGC_MODE, JSGC_MODE_INCREMENTAL);
+    JS_SetFinalizeCallback(rt, FinalizeCallback);
+
+    /* Full GC, non-incremental. */
+    FinalizeCalls = 0;
+    JS_GC(rt);
+    CHECK(rt->gcIsFull);
+    CHECK(checkSingleGroup());
+    CHECK(checkFinalizeStatus());
+    CHECK(checkFinalizeIsCompartmentGC(false));
+
+    /* Full GC, incremental. */
+    FinalizeCalls = 0;
+    JS::PrepareForFullGC(rt);
+    JS::IncrementalGC(rt, JS::gcreason::API, 1000000);
+    CHECK(rt->gcIncrementalState == js::gc::NO_INCREMENTAL);
+    CHECK(rt->gcIsFull);
+    CHECK(checkMultipleGroups());
+    CHECK(checkFinalizeStatus());
+    CHECK(checkFinalizeIsCompartmentGC(false));
+
+    JS::RootedObject global1(cx, createGlobal());
+    JS::RootedObject global2(cx, createGlobal());
+    JS::RootedObject global3(cx, createGlobal());
+    CHECK(global1);
+    CHECK(global2);
+    CHECK(global3);
+
+    /* Compartment GC, non-incremental, single compartment. */
+    FinalizeCalls = 0;
+    JS::PrepareZoneForGC(global1->zone());
+    JS::GCForReason(rt, JS::gcreason::API);
+    CHECK(!rt->gcIsFull);
+    CHECK(checkSingleGroup());
+    CHECK(checkFinalizeStatus());
+    CHECK(checkFinalizeIsCompartmentGC(true));
+
+    /* Compartment GC, non-incremental, multiple compartments. */
+    FinalizeCalls = 0;
+    JS::PrepareZoneForGC(global1->zone());
+    JS::PrepareZoneForGC(global2->zone());
+    JS::PrepareZoneForGC(global3->zone());
+    JS::GCForReason(rt, JS::gcreason::API);
+    CHECK(!rt->gcIsFull);
+    CHECK(checkSingleGroup());
+    CHECK(checkFinalizeStatus());
+    CHECK(checkFinalizeIsCompartmentGC(true));
+
+    /* Compartment GC, incremental, single compartment. */
+    FinalizeCalls = 0;
+    JS::PrepareZoneForGC(global1->zone());
+    JS::IncrementalGC(rt, JS::gcreason::API, 1000000);
+    CHECK(rt->gcIncrementalState == js::gc::NO_INCREMENTAL);
+    CHECK(!rt->gcIsFull);
+    CHECK(checkSingleGroup());
+    CHECK(checkFinalizeStatus());
+    CHECK(checkFinalizeIsCompartmentGC(true));
+
+    /* Compartment GC, incremental, multiple compartments. */
+    FinalizeCalls = 0;
+    JS::PrepareZoneForGC(global1->zone());
+    JS::PrepareZoneForGC(global2->zone());
+    JS::PrepareZoneForGC(global3->zone());
+    JS::IncrementalGC(rt, JS::gcreason::API, 1000000);
+    CHECK(rt->gcIncrementalState == js::gc::NO_INCREMENTAL);
+    CHECK(!rt->gcIsFull);
+    CHECK(checkMultipleGroups());
+    CHECK(checkFinalizeStatus());
+    CHECK(checkFinalizeIsCompartmentGC(true));
+
+#ifdef JS_GC_ZEAL
+
+    /* Full GC with reset due to new compartment, becoming compartment GC. */
+
+    FinalizeCalls = 0;
+    JS_SetGCZeal(cx, 9, 1000000);
+    JS::PrepareForFullGC(rt);
+    js::GCDebugSlice(rt, true, 1);
+    CHECK(rt->gcIncrementalState == js::gc::MARK);
+    CHECK(rt->gcIsFull);
+
+    JS::RootedObject global4(cx, createGlobal());
+    js::GCDebugSlice(rt, true, 1);
+    CHECK(rt->gcIncrementalState == js::gc::NO_INCREMENTAL);
+    CHECK(!rt->gcIsFull);
+    CHECK(checkMultipleGroups());
+    CHECK(checkFinalizeStatus());
+
+    for (unsigned i = 0; i < FinalizeCalls - 1; ++i)
+        CHECK(!IsCompartmentGCBuffer[i]);
+    CHECK(IsCompartmentGCBuffer[FinalizeCalls - 1]);
+
+    JS_SetGCZeal(cx, 0, 0);
+
+#endif
+
+    /*
+     * Make some use of the globals here to ensure the compiler doesn't optimize
+     * them away in release builds, causing the compartments to be collected and
+     * the test to fail.
+     */
+    CHECK(JS_IsGlobalObject(global1));
+    CHECK(JS_IsGlobalObject(global2));
+    CHECK(JS_IsGlobalObject(global3));
+
+    JS_SetFinalizeCallback(rt, nullptr);
+    return true;
+}
+
+bool checkSingleGroup()
+{
+    CHECK(FinalizeCalls < BufferSize);
+    CHECK(FinalizeCalls == 3);
+    return true;
+}
+
+bool checkMultipleGroups()
+{
+    CHECK(FinalizeCalls < BufferSize);
+    CHECK(FinalizeCalls % 2 == 1);
+    CHECK((FinalizeCalls - 1) / 2 > 1);
+    return true;
+}
+
+bool checkFinalizeStatus()
+{
+    /*
+     * The finalize callback should be called twice for each compartment group
+     * finalized, with status JSFINALIZE_GROUP_START and JSFINALIZE_GROUP_END,
+     * and then once more with JSFINALIZE_COLLECTION_END.
+     */
+
+    for (unsigned i = 0; i < FinalizeCalls - 1; i += 2) {
+        CHECK(StatusBuffer[i] == JSFINALIZE_GROUP_START);
+        CHECK(StatusBuffer[i + 1] == JSFINALIZE_GROUP_END);
+    }
+
+    CHECK(StatusBuffer[FinalizeCalls - 1] == JSFINALIZE_COLLECTION_END);
+
+    return true;
+}
+
+bool checkFinalizeIsCompartmentGC(bool isCompartmentGC)
+{
+    for (unsigned i = 0; i < FinalizeCalls; ++i)
+        CHECK(IsCompartmentGCBuffer[i] == isCompartmentGC);
+
+    return true;
+}
+
+static void
+FinalizeCallback(JSFreeOp *fop, JSFinalizeStatus status, bool isCompartmentGC)
+{
+    if (FinalizeCalls < BufferSize) {
+        StatusBuffer[FinalizeCalls] = status;
+        IsCompartmentGCBuffer[FinalizeCalls] = isCompartmentGC;
+    }
+    ++FinalizeCalls;
+}
+END_TEST(testGCFinalizeCallback)