Add len() to BooleanBitfield

src/utils/test_helpers.rs

@@ -4,6 +4,8 @@ use super::bls::Keypair;
 use self::rand::thread_rng;
 
 // Returns a keypair for use in testing purposes.
+// It is dangerous because we provide no guarantees
+// that the private key is unique or in-fact private.
 pub fn get_dangerous_test_keypair() -> Keypair {
     let mut rng = thread_rng();
     Keypair::generate(&mut rng)