@Test
  public void testMerge() {
    createSingleRecord();
    RepositoryVersionEntity entity = repositoryVersionDAO.findByPK(FIRST_ID);
    entity.setDisplayName("newname");
    repositoryVersionDAO.merge(entity);
    entity = repositoryVersionDAO.findByPK(FIRST_ID);
    Assert.assertEquals("newname", entity.getDisplayName());
  }
CrudDAO unit tests.
Uses repo_version table for in-memory DB tests.
ambari-server/src/test/java/org/apache/ambari/server/orm/dao/CrudDAOTest.java