@Override
  public void validateOutputFilePrefixSupported(String filePrefix) {
    verifyPath(filePrefix);
    verifyPathIsAccessible(filePrefix, "Output path does not exist or is not writeable: %s");
  }
@Test
  public void testInvalidOutputPrefix() {
    expectedException.expect(IllegalArgumentException.class);
    expectedException.expectMessage("Expected a valid 'gs://' path but was given '/local/path'");
    validator.validateOutputFilePrefixSupported("/local/path");
  }