--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
 2010-11-11  Bruno Haible  <bruno@clisp.org>
 
+	Tests for module 'strerror_r-posix'.
+	* modules/strerror_r-posix-tests: New file.
+	* tests/test-strerror_r.c: New file.
+	* tests/test-string-c++.cc: Check the signature of strerror_r.
+
 	New module 'strerror_r-posix'.
 	* lib/string.in.h (strerror_r): New declaration.
 	* lib/strerror_r.c: New file.

new file mode 100644
--- /dev/null
+++ b/modules/strerror_r-posix-tests
@@ -0,0 +1,12 @@
+Files:
+tests/test-strerror_r.c
+tests/signature.h
+tests/macros.h
+
+Depends-on:
+
+configure.ac:
+
+Makefile.am:
+TESTS += test-strerror_r
+check_PROGRAMS += test-strerror_r

new file mode 100644
--- /dev/null
+++ b/tests/test-strerror_r.c
@@ -0,0 +1,94 @@
+/* Test of strerror_r() function.
+   Copyright (C) 2007-2010 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, 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, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+#include <config.h>
+
+#include <string.h>
+
+#include "signature.h"
+SIGNATURE_CHECK (strerror_r, int, (int, char *, size_t));
+
+#include <errno.h>
+
+#include "macros.h"
+
+int
+main (void)
+{
+  char buf[100];
+  int ret;
+
+  /* Test results with valid errnum and enough room.  */
+
+  buf[0] = '\0';
+  ASSERT (strerror_r (EACCES, buf, sizeof (buf)) == 0);
+  ASSERT (buf[0] != '\0');
+
+  buf[0] = '\0';
+  ASSERT (strerror_r (ETIMEDOUT, buf, sizeof (buf)) == 0);
+  ASSERT (buf[0] != '\0');
+
+  buf[0] = '\0';
+  ASSERT (strerror_r (EOVERFLOW, buf, sizeof (buf)) == 0);
+  ASSERT (buf[0] != '\0');
+
+  /* Test results with out-of-range errnum and enough room.  */
+
+  buf[0] = '^';
+  ret = strerror_r (0, buf, sizeof (buf));
+  ASSERT (ret == 0 || ret == EINVAL);
+  if (ret == 0)
+    ASSERT (buf[0] != '^');
+
+  buf[0] = '^';
+  ret = strerror_r (-3, buf, sizeof (buf));
+  ASSERT (ret == 0 || ret == EINVAL);
+  if (ret == 0)
+    ASSERT (buf[0] != '^');
+
+  /* Test results with a too small buffer.  */
+
+  ASSERT (strerror_r (EACCES, buf, sizeof (buf)) == 0);
+  {
+    size_t len = strlen (buf);
+    size_t i;
+
+    for (i = 0; i <= len; i++)
+      {
+        strcpy (buf, "BADFACE");
+        ret = strerror_r (EACCES, buf, i);
+        if (ret == 0)
+          {
+            /* Truncated result.  POSIX allows this, and it actually
+               happens on AIX 6.1.  */
+            ASSERT (strcmp (buf, "BADFACE") != 0);
+          }
+        else
+          {
+            /* Failure.  */
+            ASSERT (ret == ERANGE);
+            /* buf is clobbered nevertheless, on FreeBSD and MacOS X.  */
+          }
+      }
+
+    strcpy (buf, "BADFACE");
+    ret = strerror_r (EACCES, buf, len + 1);
+    ASSERT (ret == 0);
+  }
+
+  return 0;
+}

--- a/tests/test-string-c++.cc
+++ b/tests/test-string-c++.cc
@@ -126,6 +126,10 @@
 SIGNATURE_CHECK (GNULIB_NAMESPACE::strerror, char *, (int));
 #endif
 
+#if GNULIB_TEST_STRERROR_R
+SIGNATURE_CHECK (GNULIB_NAMESPACE::strerror_r, int, (int, char *, size_t));
+#endif
+
 #if GNULIB_TEST_STRSIGNAL
 SIGNATURE_CHECK (GNULIB_NAMESPACE::strsignal, char *, (int));
 #endif