[SQUASH] more nits

src/fp.rs

@@ -3,10 +3,8 @@
 
 //! Finite field arithmetic for any field GF(p) for which p < 2^126.
 
-// TODO(cjpatton) Pre-compute the principal roots of unity instead of generating them on the fly.
-
-use rand::prelude::*;
-use rand::Rng;
+#[cfg(test)]
+use rand::{prelude::*, Rng};
 
 /// This structure represents the parameters of a finite field GF(p) for which p < 2^126.
 #[derive(Debug, PartialEq, Eq)]
@@ -221,6 +219,7 @@ impl FieldParameters {
     }
 
     /// Returns a random field element mapped.
+    #[cfg(test)]
     pub fn rand_elem<R: Rng + ?Sized>(&self, rng: &mut R) -> u128 {
         let uniform = rand::distributions::Uniform::from(0..self.p);
         self.elem(uniform.sample(rng))
@@ -237,6 +236,7 @@ impl FieldParameters {
     }
 
     /// Returns the number of bytes required to encode field elements.
+    #[cfg(test)] // This code is only used by tests for now.
     pub fn size(&self) -> usize {
         (16 - (self.p.leading_zeros() / 8)) as usize
     }