@Test
public void testValidateKeyset_emptyKeyset_shouldFail() throws Exception {

  try {
    Util.validateKeyset(Keyset.newBuilder().build());
    fail("Invalid keyset. Expect GeneralSecurityException");
  } catch (GeneralSecurityException e) {
    assertExceptionContains(e, "keyset must contain at least one ENABLED key");
  }
}