@Test
public void testCreatePrincipalEmptyKeyTabString() throws IOException {

  MockClientContext mockClientContext = new MockClientContext(DEFAULT_JOB_NAME);
  RunJobParameters parameters = mock(RunJobParameters.class);
  when(parameters.getPrincipal()).thenReturn("principal");
  when(parameters.getKeytab()).thenReturn("");
  FileSystemOperations fsOperations =
      new FileSystemOperations(mockClientContext);
  KerberosPrincipal result =
      KerberosPrincipalFactory.create(fsOperations,
          mockClientContext.getRemoteDirectoryManager(), parameters);
  assertNull(result);
}