message: Add one more check to the test
diff: @@ -192,6 +192,7 @@ mod tests {
  // If the initial set has too few signatures, the result should be `None`.
  let sigs = create_signatures(rng, &keys, threshold.saturating_sub(1));
  + assert!(check_sufficient_finality_signatures(&weights, ftt, &sigs).is_err());
  let minimal_set = get_minimal_set_of_signatures(&weights, ftt, sigs);
  assert!(minimal_set.is_none());
  