Add one call to yaz_mutex_destroy in test

diff --git a/test/test_mutex.c b/test/test_mutex.c
index 66d6481..843ea8f 100644 (file)
--- a/test/test_mutex.c
+++ b/test/test_mutex.c
@@ -28,6 +28,8 @@ static void tst(void)
     yaz_mutex_leave(p);
     yaz_mutex_destroy(&p);
     YAZ_CHECK(p == 0);
+
+    yaz_mutex_destroy(&p); /* OK to "destroy" NULL handle */
 }
 
 int main (int argc, char **argv)