@Test
  public void testDbConnectorNoLocks() throws Exception {
    driver.run("DROP CONNECTOR IF EXISTS derby_auth");

    driver.run("CREATE CONNECTOR IF NOT EXISTS derby_auth " +
      "TYPE 'derby' " +
      "URL 'jdbc:derby:./target/tmp/junit_metastore_db;create=true' " +
      "WITH DCPROPERTIES ( " +
      "   'hive.sql.dbcp.username'='APP', " +
      "   'hive.sql.dbcp.password'='mine')");
    
    driver.compileAndRespond("DROP CONNECTOR derby_auth");
    
    driver.lockAndRespond();
    List<ShowLocksResponseElement> locks = getLocks();
    Assert.assertEquals("Unexpected lock count", 0, locks.size());
  }
T7 is a table with 2 partitions
1. run select from T7
2. run drop partition from T7
concurrently with 1 starting first so that 2 blocks
3. start another concurrent select on T7 - it should block behind waiting X (from drop) - LM should be fair
4. finish #1 so that drop unblocks
5. rollback the drop to release its X lock
6. # should unblock
ql/src/test/org/apache/hadoop/hive/ql/lockmgr/TestDbTxnManager2.java