test-time-util: Properly restore TZ variable

The test fails to call tzset() after unsetting TZ variable, which
could break other tests. Also, let's be nicer and actually restore
the TZ to its original value.

1 files changed, 5 insertions, 1 deletions

diff --git a/src/test/test-time-util.c b/src/test/test-time-util.c
index 53f8114501..0992a31659 100644
--- a/src/test/test-time-util.c
+++ b/src/test/test-time-util.c
@@ -1,5 +1,6 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
+#include "env-util.h"
 #include "random-util.h"
 #include "serialize.h"
 #include "string-util.h"
@@ -570,6 +571,8 @@ static void test_usec_shift_clock(void) {
 static void test_in_utc_timezone(void) {
         log_info("/* %s */", __func__);
 
+        const char *tz = getenv("TZ");
+
         assert_se(setenv("TZ", ":UTC", 1) >= 0);
         assert_se(in_utc_timezone());
         assert_se(streq(tzname[0], "UTC"));
@@ -582,7 +585,8 @@ static void test_in_utc_timezone(void) {
         assert_se(streq(tzname[0], "CET"));
         assert_se(streq(tzname[1], "CEST"));
 
-        assert_se(unsetenv("TZ") == 0);
+        assert_se(set_unset_env("TZ", tz, true) == 0);
+        tzset();
 }
 
 static void test_map_clock_usec(void) {