Implement test for stack initial push edge

src/core/support/stack_lockfree.c

@@ -112,7 +112,7 @@ int gpr_stack_lockfree_push(gpr_stack_lockfree *stack, int entry) {
   } while (!gpr_atm_rel_cas(&(stack->head.atm),
                             head.atm, newhead.atm));
   /* Use rel_cas above to make sure that entry index is set properly */
-  return head.atm == INVALID_ENTRY_INDEX;
+  return head.contents.index == INVALID_ENTRY_INDEX;
 }
 
 int gpr_stack_lockfree_pop(gpr_stack_lockfree *stack) {

test/core/support/stack_lockfree_test.c

@@ -62,7 +62,7 @@ static void test_serial_sized(int size) {
   for (i=1; i<size; i*=2) {
     int j;
     for (j=0; j<=i; j++) {
-      gpr_stack_lockfree_push(stack, j);
+      GPR_ASSERT(gpr_stack_lockfree_push(stack, j) == (j==0));
     }
     for (j=0; j<=i; j++) {
       GPR_ASSERT(gpr_stack_lockfree_pop(stack) == i-j);