rootDir = Jimfs.newFileSystem(Configuration.unix()).getPath("/tmp");
    Files.createDirectory(rootDir);
  }

  @Override
  public void tearDown() throws IOException {
    rootDir.getFileSystem().close();
  }

  public void testFileTraverser_emptyDirectory() throws Exception {
    assertThat(MoreFiles.fileTraverser().breadthFirst(rootDir)).containsExactly(rootDir);
  }

      //      worrying about a symlink.
      return null;
    } else {
      // "foo" (working dir)
      return path.getFileSystem().getPath(".");
    }
  }

  /** Checks that the given options allow an insecure delete, throwing an exception if not. */
  private static void checkAllowsInsecure(Path path, RecursiveDeleteOption[] options)