@Test
  public void testCloseAfterIncRef() throws Exception {
    Directory dir = newDirectory();
    DirectoryTaxonomyWriter ltw = new DirectoryTaxonomyWriter(dir);
    ltw.addCategory(new FacetLabel("a"));
    ltw.close();

    DirectoryTaxonomyReader ltr = new DirectoryTaxonomyReader(dir);
    ltr.incRef();
    ltr.close();

    // should not fail as we incRef() before close
    ltr.getSize();
    ltr.decRef();

    dir.close();
  }