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.

diff --git a/src/test/test-time-util.c b/src/test/test-time-util.c
index 53f811450170d1347390cfe171a109cdcac3af6a..0992a316598086456c48d13dfa2026ba5a79018c 100644 (file)
--- 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) {