public void testNoProviders() {
    ProviderList providers = Providers.getProviderList();
    Providers.setProviderList(ProviderList.newList());
    try {
      Hashing.hmacMd5(MD5_KEY);
      fail("expected ISE");
    } catch (IllegalStateException expected) {
    } finally {
      Providers.setProviderList(providers);
    }
  }

  public void testMultipleUpdates() throws Exception {