code: public void testBackgroundEvictionThread() throws Exception {
    long maxSize=100000;
    long blockSize=calculateBlockSizeDefault(maxSize,9);
    LruBlockCache cache=new LruBlockCache(maxSize,blockSize);
    Block[] blocks=generateFixedBlocks(10,blockSize,"block");
    for (  Block block : blocks) {
      cache.cacheBlock(block.blockName,block.buf);
    }
    int n=0;
    while (cache.getEvictionCount() == 0) {
      System.out.println("sleep");
      Thread.sleep(1000);
      assertTrue(n++ < 2);
    }
    System.out.println("Background Evictions run: " + cache.getEvictionCount());
    assertEquals(cache.getEvictionCount(),1);
  }
  