time: Add tests.

* tests/test-time.c: New file.
* modules/time-tests: New file.

3 files changed, 66 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index d65b3393c4..580b78c331 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 2023-03-08  Bruno Haible  <bruno@clisp.org>
 
+	time: Add tests.
+	* tests/test-time.c: New file.
+	* modules/time-tests: New file.
+
 	time: New module.
 	* lib/time.in.h (time): New declaration.
 	* lib/time.c: New file.
diff --git a/modules/time-tests b/modules/time-tests
new file mode 100644
index 0000000000..e817f332cb
--- /dev/null
+++ b/modules/time-tests
@@ -0,0 +1,13 @@
+Files:
+tests/test-time.c
+tests/signature.h
+tests/macros.h
+
+Depends-on:
+gettimeofday
+
+configure.ac:
+
+Makefile.am:
+TESTS += test-time
+check_PROGRAMS += test-time
diff --git a/tests/test-time.c b/tests/test-time.c
new file mode 100644
index 0000000000..3986ee2f3d
--- /dev/null
+++ b/tests/test-time.c
@@ -0,0 +1,49 @@
+/* Test of time() function.
+   Copyright (C) 2023 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+/* Written by Bruno Haible.  */
+
+#include <config.h>
+
+#include <time.h>
+
+#include "signature.h"
+SIGNATURE_CHECK (time, time_t, (time_t *));
+
+#include <sys/time.h>
+
+#include "macros.h"
+
+int
+main (void)
+{
+  /* Check consistency of time() with gettimeofday().tv_sec.  */
+  struct timeval tv1;
+  struct timeval tv2;
+  time_t tt3;
+
+  /* Wait until gettimeofday() reports an increase in tv_sec.  */
+  ASSERT (gettimeofday (&tv1, NULL) == 0);
+  do
+    ASSERT (gettimeofday (&tv2, NULL) == 0);
+  while (tv2.tv_sec == tv1.tv_sec);
+  /* We are now at the beginning of a second.  Test whether time() reports
+     the new second or the previous one.  */
+  tt3 = time (NULL);
+  ASSERT (tt3 >= tv2.tv_sec);
+
+  return 0;
+}