@Test
  public void testNonErrorCase() throws IOException, InterruptedException {
    bc.cacheBlock(this.plainKey, this.plainCacheable);
    doDrainOfOneEntry(this.bc, this.wt, this.q);
  }
Test non-error case just works.
hbase-server/src/test/java/org/apache/hadoop/hbase/io/hfile/bucket/TestBucketWriterThread.java