From c015e64e8e2c41dd4e3e08e1d071d0746a3ae0f7 Mon Sep 17 00:00:00 2001
From: Marian Buschsieweke <marian.buschsieweke@ovgu.de>
Date: Wed, 16 Dec 2020 10:13:43 +0100
Subject: [PATCH] tests/sys_atomic_utils_unittests: spice up test

Initializing the state variables per loop with a value where some bits are set
and some are cleared makes much more sense. E.g. previously the bitwise and
applied on the state variable initialized with zero was unlikely to detect
implementation issues, as the state value never changed. So if the bitwise
and would be incorrectly implemented as a nop, it would have passed the unit
test.
---
 tests/sys_atomic_utils_unittests/main.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/tests/sys_atomic_utils_unittests/main.c b/tests/sys_atomic_utils_unittests/main.c
index eb8eadd0d6..70a5993db2 100644
--- a/tests/sys_atomic_utils_unittests/main.c
+++ b/tests/sys_atomic_utils_unittests/main.c
@@ -55,9 +55,9 @@ static void test_load_store(void)
 
 static void test_fetch_op_u8(fetch_op_u8_t atomic_op, fetch_op_u8_t op)
 {
-    uint8_t state1 = 0, state2 = 0;
     uint8_t i = 0;
     do {
+        uint8_t state1 = 0x55, state2 = 0x55;
         atomic_op(&state1, i);
         op(&state2, i);
         TEST_ASSERT_EQUAL_INT(state1, state2);
@@ -81,9 +81,9 @@ static void test_fetch_ops_u8(void)
 
 static void test_fetch_op_u16(fetch_op_u16_t atomic_op, fetch_op_u16_t op)
 {
-    uint16_t state1 = 0, state2 = 0;
     uint8_t i = 0;
     do {
+        uint16_t state1 = 0x5555, state2 = 0x5555;
         uint16_t num = random_uint32();
         atomic_op(&state1, num);
         op(&state2, num);
@@ -108,9 +108,9 @@ static void test_fetch_ops_u16(void)
 
 static void test_fetch_op_u32(fetch_op_u32_t atomic_op, fetch_op_u32_t op)
 {
-    uint32_t state1 = 0, state2 = 0;
     uint8_t i = 0;
     do {
+        uint32_t state1 = 0x55555555, state2 = 0x55555555;
         uint32_t num = random_uint32();
         atomic_op(&state1, num);
         op(&state2, num);
@@ -135,9 +135,10 @@ static void test_fetch_ops_u32(void)
 
 static void test_fetch_op_u64(fetch_op_u64_t atomic_op, fetch_op_u64_t op)
 {
-    uint64_t state1 = 0, state2 = 0;
     uint8_t i = 0;
     do {
+        uint64_t state1, state2;
+        state1 = state2 = 0x5555555555555555;
         uint64_t num;
         random_bytes((void *)&num, sizeof(num));
         atomic_op(&state1, num);