@Test
  public void nothing() throws Exception {
    // Test that the whole things works when there's nothing in the queue.  This is just a
    // survival test.
    startWorker();
  }
Tests for the worker thread and its MR jobs.
todo: most delta files in this test suite use txn id range, i.e. [N,N+M]
That means that they all look like they were created by compaction or by streaming api.
Delta files created by SQL should have [N,N] range (and a suffix in v1.3 and later)
Need to change some of these to have better test coverage.
ql/src/test/org/apache/hadoop/hive/ql/txn/compactor/TestWorker.java