From 747f71ca80db6994ed839dc79eac2b52abb3915a Mon Sep 17 00:00:00 2001
From: therealyingtong <yingtong@z.cash>
Date: Tue, 15 Jun 2021 13:37:12 +0800
Subject: [PATCH] constants.rs: Add unit tests for T_P, T_Q constants.

---
 src/constants.rs | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/src/constants.rs b/src/constants.rs
index 4c488692..d6002c4a 100644
--- a/src/constants.rs
+++ b/src/constants.rs
@@ -268,7 +268,7 @@ fn test_zs_and_us<C: CurveAffine>(base: C, z: &[u64], u: &[[[u8; 32]; H]], num_w
 #[cfg(test)]
 mod tests {
     use ff::PrimeField;
-    use pasta_curves::pallas;
+    use pasta_curves::{arithmetic::FieldExt, pallas};
 
     #[test]
     // Nodes in the Merkle tree are Pallas base field elements.
@@ -287,4 +287,18 @@ mod tests {
     fn l_orchard_scalar() {
         assert_eq!(super::L_ORCHARD_SCALAR, pallas::Scalar::NUM_BITS as usize);
     }
+
+    #[test]
+    fn t_q() {
+        let t_q = pallas::Scalar::from_u128(super::T_Q);
+        let two_pow_254 = pallas::Scalar::from_u128(1 << 127).square();
+        assert_eq!(t_q + two_pow_254, pallas::Scalar::zero());
+    }
+
+    #[test]
+    fn t_p() {
+        let t_p = pallas::Base::from_u128(super::T_P);
+        let two_pow_254 = pallas::Base::from_u128(1 << 127).square();
+        assert_eq!(t_p + two_pow_254, pallas::Base::zero());
+    }
 }