public Optional<AlluxioURI> getRootUfsUri() {
    return Optional.ofNullable(mRootUfsUri);
  }
@Test
  public void testGetRootUfsUri() {
    mJCommander.parse("-m", "/tmp/fuse-mp", "-u", "scheme://host/path");
    assertEquals(Optional.of(new AlluxioURI("scheme://host/path")), mOptions.getRootUfsUri());
  }