--- weak-marking-02.js
+++ weak-marking-02.js
@@ -0,0 +1,63 @@
+// These tests will be using object literals as keys, and we want some of them
+// to be dead after being inserted into a WeakMap. That means we must wrap
+// everything in functions because it seems like the toplevel script hangs onto
+// its object literals.
+
+// Cross-compartment WeakMap keys work by storing a cross-compartment wrapper
+// in the WeakMap, and the actual "delegate" object in the target compartment
+// is the thing whose liveness is checked.
+
+var g2 = newGlobal();
+g2.eval('function genObj(name) { return {"name": name} }');
+
+function basicSweeping() {
+  var wm1 = new WeakMap();
+  wm1.set({'name': 'obj1'}, {'name': 'val1'});
+  var hold = g2.genObj('obj2');
+  wm1.set(hold, {'name': 'val2'});
+  wm1.set({'name': 'obj3'}, {'name': 'val3'});
+  var obj4 = g2.genObj('obj4');
+  wm1.set(obj4, {'name': 'val3'});
+  obj4 = undefined;
+
+  gc();
+  assertEq(wm1.get(hold).name, 'val2');
+  assertEq(nondeterministicGetWeakMapKeys(wm1).length, 1);
+}
+
+basicSweeping();
+
+// Same, but behind an additional WM layer, to avoid ordering problems (not
+// that I've checked that basicSweeping even has any problems.)
+function basicSweeping2() {
+  var wm1 = new WeakMap();
+  wm1.set({'name': 'obj1'}, {'name': 'val1'});
+  var hold = g2.genObj('obj2');
+  wm1.set(hold, {'name': 'val2'});
+  wm1.set({'name': 'obj3'}, {'name': 'val3'});
+  var obj4 = g2.genObj('obj4');
+  wm1.set(obj4, {'name': 'val3'});
+  obj4 = undefined;
+
+  var base1 = {'name': 'base1'};
+  var base2 = {'name': 'base2'};
+  var wm_base1 = new WeakMap();
+  var wm_base2 = new WeakMap();
+  wm_base1.set(base1, wm_base2);
+  wm_base2.set(base2, wm1);
+  wm1 = wm_base2 = undefined;
+  
+  gc();
+
+  assertEq(nondeterministicGetWeakMapKeys(wm_base1).length, 1);
+  wm_base2 = wm_base1.get(base1);
+  assertEq(nondeterministicGetWeakMapKeys(wm_base2).length, 1);
+  assertEq(nondeterministicGetWeakMapKeys(wm_base1)[0], base1);
+  assertEq(nondeterministicGetWeakMapKeys(wm_base2)[0], base2);
+  wm_base2 = wm_base1.get(base1);
+  wm1 = wm_base2.get(base2);
+  assertEq(wm1.get(hold).name, 'val2');
+  assertEq(nondeterministicGetWeakMapKeys(wm1).length, 1);
+}
+
+basicSweeping2();