new file mode 100644
--- /dev/null
+++ b/tests/test-ptsname.c
@@ -0,0 +1,86 @@
+/* Test of ptsname(3).
+   Copyright (C) 2010 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 <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+#include <stdlib.h>
+
+#include "signature.h"
+SIGNATURE_CHECK (ptsname, char *, (int));
+
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "macros.h"
+
+int
+main (void)
+{
+  {
+    int fd;
+    char *result;
+
+    /* Open the controlling tty of the current process.  */
+    fd = open ("/dev/tty", O_RDONLY);
+    if (fd < 0)
+      {
+        fprintf (stderr, "Skipping test: cannot open controlling tty\n");
+        return 77;
+      }
+
+    result = ptsname (fd);
+    /* The result is usually NULL, because /dev/tty is a slave, not a
+       master.  */
+    if (result != NULL)
+      {
+        ASSERT (memcmp (result, "/dev/", 5) == 0);
+      }
+
+    close (fd);
+  }
+
+  /* Try various master names of MacOS X.  */
+  {
+    int char1;
+    int char2;
+
+    for (char1 = 'p'; char1 <= 'w'; char1++)
+      for (char2 = '0'; char2 <= 'f'; char2 = (char2 == '9' ? 'a' : char2 + 1))
+        {
+          char master_name[32];
+          int fd;
+
+          sprintf (master_name, "/dev/pty%c%c", char1, char2);
+          fd = open (master_name, O_RDONLY);
+          if (fd >= 0)
+            {
+              char *result;
+              char slave_name[32];
+
+              result = ptsname (fd);
+              ASSERT (result != NULL);
+              sprintf (slave_name, "/dev/tty%c%c", char1, char2);
+              ASSERT (strcmp (result, slave_name) == 0);
+
+              close (fd);
+            }
+        }
+  }
+
+  return 0;
+}