From f7ada99d8231e777bde5a12b9a88fc68c04e86de Mon Sep 17 00:00:00 2001
From: Daniel Sanchez Quiros <sanchez.quiros.daniel@gmail.com>
Date: Tue, 2 Apr 2024 18:00:14 +0200
Subject: [PATCH] Implement decoding tests

---
 nomos-da/kzgrs/src/rs.rs | 43 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/nomos-da/kzgrs/src/rs.rs b/nomos-da/kzgrs/src/rs.rs
index 19f18e47..507ff727 100644
--- a/nomos-da/kzgrs/src/rs.rs
+++ b/nomos-da/kzgrs/src/rs.rs
@@ -1,4 +1,5 @@
 use ark_bls12_381::Fr;
+use ark_ff::{BigInteger, PrimeField};
 use ark_poly::univariate::DensePolynomial;
 use ark_poly::{EvaluationDomain, Evaluations, GeneralEvaluationDomain, Polynomial};
 
@@ -32,3 +33,45 @@ pub fn decode(
         *domain,
     )
 }
+
+pub fn points_to_bytes<const CHUNK_SIZE: usize>(points: &[Fr]) -> Vec<u8> {
+    fn point_to_buff<const CHUNK_SIZE: usize>(p: &Fr) -> impl Iterator<Item = u8> {
+        p.into_bigint().to_bytes_le().into_iter().take(CHUNK_SIZE)
+    }
+    points
+        .iter()
+        .map(point_to_buff::<CHUNK_SIZE>)
+        .flatten()
+        .collect()
+}
+
+#[cfg(test)]
+mod test {
+    use crate::common::bytes_to_polynomial;
+    use crate::rs::{decode, encode, points_to_bytes};
+    use ark_bls12_381::{Bls12_381, Fr};
+    use ark_poly::univariate::DensePolynomial;
+    use ark_poly::{EvaluationDomain, GeneralEvaluationDomain};
+    use ark_poly_commit::kzg10::{UniversalParams, KZG10};
+    use once_cell::sync::Lazy;
+    use rand::{thread_rng, Fill};
+
+    const COEFFICIENTS_SIZE: usize = 16;
+    static DOMAIN: Lazy<GeneralEvaluationDomain<Fr>> =
+        Lazy::new(|| GeneralEvaluationDomain::new(COEFFICIENTS_SIZE).unwrap());
+
+    #[test]
+    fn test_encode_decode() {
+        let mut bytes: [u8; 310] = [0; 310];
+        let mut rng = thread_rng();
+        bytes.try_fill(&mut rng).unwrap();
+
+        let (evals, poly) = bytes_to_polynomial::<31>(&bytes, *DOMAIN).unwrap();
+
+        let mut encoded = encode(&poly, &evals, 2, &DOMAIN);
+
+        let decoded = decode(10, &encoded.evals, &DOMAIN);
+        let decoded_bytes = points_to_bytes::<31>(&decoded.evals);
+        assert_eq!(decoded_bytes, bytes);
+    }
+}