--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 2010-01-10  Bruno Haible  <bruno@clisp.org>
 
+	Tests for module 'unistr/u32-prev'.
+	* modules/unistr/u32-prev-tests: New file.
+	* tests/unistr/test-u32-prev.c: New file.
+
 	Tests for module 'unistr/u16-prev'.
 	* modules/unistr/u16-prev-tests: New file.
 	* tests/unistr/test-u16-prev.c: New file.

new file mode 100644
--- /dev/null
+++ b/modules/unistr/u32-prev-tests
@@ -0,0 +1,12 @@
+Files:
+tests/unistr/test-u32-prev.c
+tests/macros.h
+
+Depends-on:
+
+configure.ac:
+
+Makefile.am:
+TESTS += test-u32-prev
+check_PROGRAMS += test-u32-prev
+test_u32_prev_SOURCES = unistr/test-u32-prev.c

new file mode 100644
--- /dev/null
+++ b/tests/unistr/test-u32-prev.c
@@ -0,0 +1,133 @@
+/* Test of u32_prev() 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"
+
+static int
+check (const uint32_t *input, size_t input_length, ucs4_t *puc)
+{
+  ucs4_t uc;
+
+  /* Test recognition when at the beginning of the string.  */
+  if (u32_prev (&uc, input + input_length, input) != input)
+    return 1;
+
+  /* Test recognition when preceded by a 1-unit character.  */
+  {
+    uint32_t buf[100];
+    uint32_t *ptr;
+    size_t i;
+    ucs4_t uc1;
+
+    ptr = buf;
+    *ptr++ = 0x1D51E;
+    for (i = 0; i < input_length; i++)
+      ptr[i] = input[i];
+
+    if (u32_prev (&uc1, ptr + input_length, buf) != ptr)
+      return 2;
+    if (uc1 != uc)
+      return 3;
+  }
+
+  *puc = uc;
+  return 0;
+}
+
+static int
+check_invalid (const uint32_t *input, size_t input_length)
+{
+#if CONFIG_UNICODE_SAFETY
+  ucs4_t uc;
+
+  /* Test recognition when at the beginning of the string.  */
+  uc = 0xBADFACE;
+  if (u32_prev (&uc, input + input_length, input) != NULL)
+    return 1;
+  if (uc != 0xBADFACE)
+    return 2;
+
+  /* Test recognition when preceded by a 1-unit character.  */
+  {
+    uint32_t buf[100];
+    uint32_t *ptr;
+    size_t i;
+
+    ptr = buf;
+    *ptr++ = 0x1D51E;
+    for (i = 0; i < input_length; i++)
+      ptr[i] = input[i];
+
+    uc = 0xBADFACE;
+    if (u32_prev (&uc, ptr + input_length, buf) != NULL)
+      return 3;
+    if (uc != 0xBADFACE)
+      return 4;
+  }
+#endif
+
+  return 0;
+}
+
+int
+main ()
+{
+  ucs4_t uc;
+
+  /* Test ISO 646 unit input.  */
+  {
+    ucs4_t c;
+    uint32_t buf[1];
+
+    for (c = 0; c < 0x80; c++)
+      {
+        buf[0] = c;
+        uc = 0xBADFACE;
+        ASSERT (check (buf, 1, &uc) == 0);
+        ASSERT (uc == c);
+      }
+  }
+
+  /* Test BMP unit input.  */
+  {
+    static const uint32_t input[] = { 0x20AC };
+    uc = 0xBADFACE;
+    ASSERT (check (input, SIZEOF (input), &uc) == 0);
+    ASSERT (uc == 0x20AC);
+  }
+
+  /* Test non-BMP unit input.  */
+  {
+    static const uint32_t input[] = { 0x1D51F };
+    uc = 0xBADFACE;
+    ASSERT (check (input, SIZEOF (input), &uc) == 0);
+    ASSERT (uc == 0x1D51F);
+  }
+
+  /* Test incomplete/invalid 1-unit input.  */
+  {
+    static const uint32_t input[] = { 0x340000 };
+    ASSERT (check_invalid (input, SIZEOF (input)) == 0);
+  }
+
+  return 0;
+}