clock-util: make clock_is_localtime() testable and add initial tests

Add path argument to clock_is_localtime() and default to "/etc/adjtime" if it's
NULL. This makes the function testable.

Add test-clock: initial test cases for some scenarios, using a temporary file.
This also checks the behaviour with a NULL (i. e. the system's /etc/adjtime)
file.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/timedate/timedated.c b/src/timedate/timedated.c
index 2a10135fba..55c24ac4f0 100644
--- a/src/timedate/timedated.c
+++ b/src/timedate/timedated.c
@@ -78,7 +78,7 @@ static int context_read_data(Context *c) {
         c->zone = t;
         t = NULL;
 
-        c->local_rtc = clock_is_localtime() > 0;
+        c->local_rtc = clock_is_localtime(NULL) > 0;
 
         return 0;
 }