message: added logger to test
diff: @@ -321,6 +321,8 @@ mod tests {
  #[test]
  fn generate_prime_in_range_works() {
  + ::env_logger::init().unwrap();
  +
  let bn = BigNumber::new().unwrap();
  let start = bn.rand(250).unwrap();
  let end = bn.rand(300).unwrap();
  