testGetDummyResourceUri() {
    /** @suppress {visibility} suppression added to enable type checking */
    const url = CrossDomainRpc.getDummyResourceUri_();
    assertTrue(
        'dummy resource URL should not contain "?"', url.indexOf('?') < 0);
    assertTrue(
        'dummy resource URL should not contain "#"', url.indexOf('#') < 0);
  }
@suppress {visibility} suppression added to enable type
                 checking