From 7d8d5c86df8b27b45e80ed50341dd0ce64546c0f Mon Sep 17 00:00:00 2001
From: Sebastian Falbesoner <sebastian.falbesoner@gmail.com>
Date: Sun, 25 Jun 2023 22:14:13 +0200
Subject: [PATCH] tests: refactor: take use of `secp256k1_ge_x_on_curve_var`

The recently merged ellswift PR (#1129) introduced a helper
`secp256k1_ge_x_on_curve_var` to check if a given X coordinate is
valid (i.e. the expression x^3 + 7 is square, see commit
79e5b2a8b80f507e2c9936ff1c4e2fb39bc66a4e). This can be used for code
deduplication in the `ecmult_const_mult_xonly` test.
---
 src/tests.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/src/tests.c b/src/tests.c
index 8ada3f869b808..fd106b8fb9526 100644
--- a/src/tests.c
+++ b/src/tests.c
@@ -4611,17 +4611,14 @@ static void ecmult_const_mult_xonly(void) {
 
     /* Test that secp256k1_ecmult_const_xonly correctly rejects X coordinates not on curve. */
     for (i = 0; i < 2*COUNT; ++i) {
-        secp256k1_fe x, n, d, c, r;
+        secp256k1_fe x, n, d, r;
         int res;
         secp256k1_scalar q;
         random_scalar_order_test(&q);
         /* Generate random X coordinate not on the curve. */
         do {
             random_field_element_test(&x);
-            secp256k1_fe_sqr(&c, &x);
-            secp256k1_fe_mul(&c, &c, &x);
-            secp256k1_fe_add_int(&c, SECP256K1_B);
-        } while (secp256k1_fe_is_square_var(&c));
+        } while (secp256k1_ge_x_on_curve_var(&x));
         /* If i is odd, n=d*x for random non-zero d. */
         if (i & 1) {
             do {