--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
 2008-12-21  Bruno Haible  <bruno@clisp.org>
 
+	* modules/wcrtomb-tests: New file.
+	* tests/test-wcrtomb.sh: New file.
+	* tests/test-wcrtomb.c: New file.
+
+	New module 'wcrtomb'.
 	* lib/wchar.in.h (wcrtomb): New declaration.
 	* lib/wcrtomb.c: New file.
 	* m4/wcrtomb.m4: New file.

new file mode 100644
--- /dev/null
+++ b/modules/wcrtomb-tests
@@ -0,0 +1,27 @@
+Files:
+tests/test-wcrtomb.sh
+tests/test-wcrtomb.c
+m4/locale-fr.m4
+m4/locale-ja.m4
+m4/locale-zh.m4
+m4/codeset.m4
+
+Depends-on:
+btowc
+
+configure.ac:
+gt_LOCALE_FR
+gt_LOCALE_FR_UTF8
+gt_LOCALE_JA
+gt_LOCALE_ZH_CN
+
+Makefile.am:
+TESTS += test-wcrtomb.sh
+TESTS_ENVIRONMENT += \
+  EXEEXT='@EXEEXT@' \
+  LOCALE_FR='@LOCALE_FR@' \
+  LOCALE_FR_UTF8='@LOCALE_FR_UTF8@' \
+  LOCALE_JA='@LOCALE_JA@' \
+  LOCALE_ZH_CN='@LOCALE_ZH_CN@'
+check_PROGRAMS += test-wcrtomb
+

new file mode 100644
--- /dev/null
+++ b/tests/test-wcrtomb.c
@@ -0,0 +1,162 @@
+/* Test of conversion of wide character to multibyte character.
+   Copyright (C) 2008 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/>.  */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2008.  */
+
+#include <config.h>
+
+#include <wchar.h>
+
+#include <locale.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define ASSERT(expr) \
+  do									     \
+    {									     \
+      if (!(expr))							     \
+        {								     \
+          fprintf (stderr, "%s:%d: assertion failed\n", __FILE__, __LINE__); \
+          fflush (stderr);						     \
+          abort ();							     \
+        }								     \
+    }									     \
+  while (0)
+
+/* Check the multibyte character s[0..n-1].  */
+static void
+check_character (const char *s, size_t n)
+{
+  wchar_t wc;
+  char buf[64];
+  int iret;
+  size_t ret;
+
+  wc = (wchar_t) 0xBADFACE;
+  iret = mbtowc (&wc, s, n);
+  ASSERT (iret == n);
+
+  ret = wcrtomb (buf, wc, NULL);
+  ASSERT (ret == n);
+  ASSERT (memcmp (buf, s, n) == 0);
+
+  /* Test special calling convention, passing a NULL pointer.  */
+  ret = wcrtomb (NULL, wc, NULL);
+  ASSERT (ret == 1);
+}
+
+int
+main (int argc, char *argv[])
+{
+  char buf[64];
+  size_t ret;
+
+  /* configure should already have checked that the locale is supported.  */
+  if (setlocale (LC_ALL, "") == NULL)
+    return 1;
+
+  /* Test NUL character.  */
+  {
+    buf[0] = 'x';
+    ret = wcrtomb (buf, 0, NULL);
+    ASSERT (ret == 1);
+    ASSERT (buf[0] == '\0');
+  }
+
+  /* Test single bytes.  */
+  {
+    int c;
+
+    for (c = 0; c < 0x100; c++)
+      switch (c)
+	{
+	case '\t': case '\v': case '\f':
+	case ' ': case '!': case '"': case '#': case '%':
+	case '&': case '\'': case '(': case ')': case '*':
+	case '+': case ',': case '-': case '.': case '/':
+	case '0': case '1': case '2': case '3': case '4':
+	case '5': case '6': case '7': case '8': case '9':
+	case ':': case ';': case '<': case '=': case '>':
+	case '?':
+	case 'A': case 'B': case 'C': case 'D': case 'E':
+	case 'F': case 'G': case 'H': case 'I': case 'J':
+	case 'K': case 'L': case 'M': case 'N': case 'O':
+	case 'P': case 'Q': case 'R': case 'S': case 'T':
+	case 'U': case 'V': case 'W': case 'X': case 'Y':
+	case 'Z':
+	case '[': case '\\': case ']': case '^': case '_':
+	case 'a': case 'b': case 'c': case 'd': case 'e':
+	case 'f': case 'g': case 'h': case 'i': case 'j':
+	case 'k': case 'l': case 'm': case 'n': case 'o':
+	case 'p': case 'q': case 'r': case 's': case 't':
+	case 'u': case 'v': case 'w': case 'x': case 'y':
+	case 'z': case '{': case '|': case '}': case '~':
+	  /* c is in the ISO C "basic character set".  */
+	  ret = wcrtomb (buf, btowc (c), NULL);
+	  ASSERT (ret == 1);
+	  ASSERT (buf[0] == (char) c);
+	  break;
+	}
+  }
+
+  if (argc > 1)
+    switch (argv[1][0])
+      {
+      case '1':
+	/* Locale encoding is ISO-8859-1 or ISO-8859-15.  */
+	{
+	  const char input[] = "B\374\337er"; /* "Büßer" */
+
+	  check_character (input + 1, 1);
+	  check_character (input + 2, 1);
+	}
+	return 0;
+
+      case '2':
+	/* Locale encoding is UTF-8.  */
+	{
+	  const char input[] = "B\303\274\303\237er"; /* "Büßer" */
+
+	  check_character (input + 1, 2);
+	  check_character (input + 3, 2);
+	}
+	return 0;
+
+      case '3':
+	/* Locale encoding is EUC-JP.  */
+	{
+	  const char input[] = "<\306\374\313\334\270\354>"; /* "<日本語>" */
+
+	  check_character (input + 1, 2);
+	  check_character (input + 3, 2);
+	  check_character (input + 5, 2);
+	}
+	return 0;
+
+      case '4':
+	/* Locale encoding is GB18030.  */
+	{
+	  const char input[] = "B\250\271\201\060\211\070er"; /* "Büßer" */
+
+	  check_character (input + 1, 2);
+	  check_character (input + 3, 4);
+	}
+	return 0;
+      }
+
+  return 1;
+}

new file mode 100755
--- /dev/null
+++ b/tests/test-wcrtomb.sh
@@ -0,0 +1,31 @@
+#!/bin/sh
+
+# Test in an ISO-8859-1 or ISO-8859-15 locale.
+: ${LOCALE_FR=fr_FR}
+if test $LOCALE_FR != none; then
+  LC_ALL=$LOCALE_FR \
+  ./test-wcrtomb${EXEEXT} 1
+fi
+
+# Test whether a specific UTF-8 locale is installed.
+: ${LOCALE_FR_UTF8=fr_FR.UTF-8}
+if test $LOCALE_FR_UTF8 != none; then
+  LC_ALL=$LOCALE_FR_UTF8 \
+  ./test-wcrtomb${EXEEXT} 2
+fi
+
+# Test whether a specific EUC-JP locale is installed.
+: ${LOCALE_JA=ja_JP}
+if test $LOCALE_JA != none; then
+  LC_ALL=$LOCALE_JA \
+  ./test-wcrtomb${EXEEXT} 3
+fi
+
+# Test whether a specific GB18030 locale is installed.
+: ${LOCALE_ZH_CN=zh_CN}
+if test $LOCALE_ZH_CN != none; then
+  LC_ALL=$LOCALE_ZH_CN \
+  ./test-wcrtomb${EXEEXT} 4
+fi
+
+exit 0