@Test
public void testGetInstance() throws DiskErrorException {

  DiskValidator diskValidator = DiskValidatorFactory.getInstance("basic");
  assertNotNull("Fail to get the instance.", diskValidator);
  assertEquals("Fail to create the correct instance.",
      diskValidator.getClass(), BasicDiskValidator.class);
  assertNotNull("Fail to cache the object", DiskValidatorFactory.INSTANCES.
      get(BasicDiskValidator.class));
}