mtx: Add tests.

* tests/test-mtx.c: New file, based on tests/test-lock.c.
* tests/test-call_once.c: New file, based on tests/test-once.c.
* modules/mtx-tests: New file.

1 files changed, 43 insertions, 0 deletions

diff --git a/tests/test-call_once.c b/tests/test-call_once.c
new file mode 100644
index 0000000000..8d2b785038
--- /dev/null
+++ b/tests/test-call_once.c
@@ -0,0 +1,43 @@
+/* Test of once-only execution in multithreaded situations.
+   Copyright (C) 2018-2019 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 <bruno@clisp.org>, 2018.  */
+
+#include <config.h>
+
+#include <threads.h>
+
+#include "macros.h"
+
+static once_flag a_once = ONCE_FLAG_INIT;
+
+static int a;
+
+static void
+a_init (void)
+{
+  a = 42;
+}
+
+int
+main ()
+{
+  call_once (&a_once, a_init);
+
+  ASSERT (a == 42);
+
+  return 0;
+}