boolean pmScan = gc.isPersistenceManagerScan();
gc.setPersistenceManagerScan(allowPmScan);
gotNullNode = false;
gotNode = false;
gc.setMarkEventListener(this);
gc.mark();
if (pmScan && allowPmScan) {
assertTrue("PM scan without null Node", gotNullNode);
assertFalse("PM scan, but got a real node", gotNode);
} else {
assertFalse("Not a PM scan - but got a null Node", gotNullNode);