public void testKeyFetchTracker() {
KeyFetchTracker tracker = new KeyFetchTracker(4);
tracker.recordFetch(cn0_1, new ByteArray(value1));
tracker.recordFetch(cn0_2, new ByteArray(value1));
tracker.recordFetch(cn0_3, new ByteArray(value1));
tracker.recordFetch(cn0_4, new ByteArray(value1));
tracker.recordFetch(cn0_1, new ByteArray(value2));
tracker.recordFetch(cn0_2, new ByteArray(value2));
tracker.recordFetch(cn0_3, new ByteArray(value2));
assertNull(tracker.nextFinished());
tracker.recordFetch(cn0_4, new ByteArray(value2));