From 8fb9e44dd291e5448b8885e0dcdca18b6f51d209 Mon Sep 17 00:00:00 2001
From: Henry de Valence <hdevalence@hdevalence.ca>
Date: Sun, 8 Jan 2017 14:56:52 -0500
Subject: [PATCH] Test that d = -121665/121666

---
 src/constants.rs | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/constants.rs b/src/constants.rs
index b6be635..428592c 100644
--- a/src/constants.rs
+++ b/src/constants.rs
@@ -1455,4 +1455,15 @@ mod test {
         let sqrt_m1_sq = &constants::SQRT_M1 * &constants::SQRT_M1;
         assert_eq!(minus_one, sqrt_m1_sq);
     }
+
+    #[test]
+    /// Test that d = -121665/121666
+    fn test_d_vs_ratio() {
+        let a = FieldElement([-121665,0,0,0,0,0,0,0,0,0]);
+        let b = FieldElement([ 121666,0,0,0,0,0,0,0,0,0]);
+        let d = &a * &b.invert();
+        let d2 = &d + &d;
+        assert_eq!(d, constants::d);
+        assert_eq!(d2, constants::d2);
+    }
 }