AbstractEvictionList implements EvictionList { protected synchronized EvictionNode unlinkHeadEntry() { EvictionNode evictionNode = head.next(); if (evictionNode == tail) { return null; } unlinkEntry(evictionNode); return evictionNode; } protected  AbstractEvictionList(EvictionController controller); @Override int size(); @Override void closeStats(); @Override EvictionCounters getStatistics(); @Override void clear(RegionVersionVector regionVersionVector, BucketRegion bucketRegion); @Override synchronized void appendEntry(final EvictionNode evictionNode); @Override synchronized void destroyEntry(EvictionNode evictionNode);  }
@Test public void unlinkHeadOnEmptyListReturnsNull() throws Exception { TestEvictionList evictionList = new TestEvictionList(controller); assertThat(evictionList.unlinkHeadEntry()).isNull(); }