--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 2010-01-10  Bruno Haible  <bruno@clisp.org>
 
+	Tests for module 'unistr/u16-mbsnlen'.
+	* modules/unistr/u16-mbsnlen-tests: New file.
+	* tests/unistr/test-u16-mbsnlen.c: New file.
+
 	Tests for module 'unistr/u8-mbsnlen'.
 	* modules/unistr/u8-mbsnlen-tests: New file.
 	* tests/unistr/test-u8-mbsnlen.c: New file.

new file mode 100644
--- /dev/null
+++ b/modules/unistr/u16-mbsnlen-tests
@@ -0,0 +1,12 @@
+Files:
+tests/unistr/test-u16-mbsnlen.c
+tests/macros.h
+
+Depends-on:
+
+configure.ac:
+
+Makefile.am:
+TESTS += test-u16-mbsnlen
+check_PROGRAMS += test-u16-mbsnlen
+test_u16_mbsnlen_SOURCES = unistr/test-u16-mbsnlen.c

new file mode 100644
--- /dev/null
+++ b/tests/unistr/test-u16-mbsnlen.c
@@ -0,0 +1,68 @@
+/* Test of u16_mbsnlen() function.
+   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/>.  */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2010.  */
+
+#include <config.h>
+
+#include "unistr.h"
+
+#include "macros.h"
+
+int
+main ()
+{
+  /* Simple string.  */
+  { /* "Grüß Gott. Здравствуйте! x=(-b±sqrt(b²-4ac))/(2a)  日本語,中文,한글" */
+    static const uint16_t input[] =
+      { 'G', 'r', 0x00FC, 0x00DF, ' ', 'G', 'o', 't', 't', '.', ' ',
+        0x0417, 0x0434, 0x0440, 0x0430, 0x0432, 0x0441, 0x0442, 0x0432, 0x0443,
+        0x0439, 0x0442, 0x0435, '!', ' ',
+        'x', '=', '(', '-', 'b', 0x00B1, 's', 'q', 'r', 't', '(', 'b', 0x00B2,
+        '-', '4', 'a', 'c', ')', ')', '/', '(', '2', 'a', ')', ' ', ' ',
+        0x65E5, 0x672C, 0x8A9E, ',', 0x4E2D, 0x6587, ',', 0xD55C, 0xAE00, '\n'
+      };
+    size_t n;
+
+    for (n = 0; n <= SIZEOF (input); n++)
+      {
+        size_t len = u16_mbsnlen (input, n);
+        ASSERT (len == n);
+      }
+  }
+
+  /* String with characters outside the BMP.  */
+  {
+    static const uint16_t input[] =
+      { '-', '(', 0xD835, 0xDD1E, 0x00D7, 0xD835, 0xDD1F, ')', '=',
+        0xD835, 0xDD1F, 0x00D7, 0xD835, 0xDD1E
+      };
+    static const size_t expected[SIZEOF (input) + 1] =
+      { 0,
+        1, 2, 3, 3, 4, 5, 5, 6, 7,
+        8, 8, 9, 10, 10
+      };
+    size_t n;
+
+    for (n = 0; n <= SIZEOF (input); n++)
+      {
+        size_t len = u16_mbsnlen (input, n);
+        ASSERT (len == expected[n]);
+      }
+  }
+
+  return 0;
+}