Merge bitcoin#814: tests: Initialize random group elements fully

5738e86 tests: Initialize random group elements fully (Tim Ruffing)

Pull request description:

  Also fix add a missing comment.

ACKs for top commit:
  sipa:
    utACK 5738e86

Tree-SHA512: c7723e225434e7044379f307b2977a3a5251080793bd87b377a2bbf1d18b39ca05f6fb3b427acec32c3b34f4de678fe7087a2dcca4b5f03ec1fc680a88d82b9a

src/group.h

@@ -59,6 +59,7 @@ static int secp256k1_ge_is_infinity(const secp256k1_ge *a);
 /** Check whether a group element is valid (i.e., on the curve). */
 static int secp256k1_ge_is_valid_var(const secp256k1_ge *a);
 
+/** Set r equal to the inverse of a (i.e., mirrored around the X axis) */
 static void secp256k1_ge_neg(secp256k1_ge *r, const secp256k1_ge *a);
 
 /** Set a group element equal to another which is given in jacobian coordinates */

src/tests.c

@@ -86,6 +86,7 @@ void random_group_element_test(secp256k1_ge *ge) {
             break;
         }
     } while(1);
+    ge->infinity = 0;
 }
 
 void random_group_element_jacobian_test(secp256k1_gej *gej, const secp256k1_ge *ge) {