f uninitialized memory in tests

Author: jonasnick

src/tests.c

@@ -4318,6 +4318,7 @@ void test_xonly_pubkey_api(void) {
     secp256k1_xonly_pubkey pk_tweaked;
     secp256k1_pubkey xy_pk;
     unsigned char sk[32];
+    unsigned char xy_sk[32];
     unsigned char buf32[32];
     unsigned char tweak[32];
     int pk_is_positive;
@@ -4337,6 +4338,8 @@ void test_xonly_pubkey_api(void) {
 
     secp256k1_rand256(sk);
     secp256k1_rand256(tweak);
+    secp256k1_rand256(xy_sk);
+    CHECK(secp256k1_ec_pubkey_create(sign, &xy_pk, xy_sk) == 1);
 
     ecount = 0;
     CHECK(secp256k1_xonly_pubkey_create(none, &pk, sk) == 0);