--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
 2010-01-10  Bruno Haible  <bruno@clisp.org>
 
+	Tests for module 'unistr/u8-chr'.
+	* modules/unistr/u8-chr-tests: New file.
+	* tests/unistr/test-u8-chr.c: New file.
+	* tests/unistr/test-chr.h: New file, based on tests/test-memchr.c.
+
 	Tests for module 'unistr/u32-cmp2'.
 	* modules/unistr/u32-cmp2-tests: New file.
 	* tests/unistr/test-u32-cmp2.c: New file.

new file mode 100644
--- /dev/null
+++ b/modules/unistr/u8-chr-tests
@@ -0,0 +1,21 @@
+Files:
+tests/unistr/test-u8-chr.c
+tests/unistr/test-chr.h
+tests/zerosize-ptr.h
+tests/macros.h
+m4/mmap-anon.m4
+
+Depends-on:
+extensions
+getpagesize
+unistr/u8-set
+
+configure.ac:
+gl_FUNC_MMAP_ANON
+AC_CHECK_HEADERS_ONCE([sys/mman.h])
+AC_CHECK_FUNCS_ONCE([mprotect])
+
+Makefile.am:
+TESTS += test-u8-chr
+check_PROGRAMS += test-u8-chr
+test_u8_chr_SOURCES = unistr/test-u8-chr.c

new file mode 100644
--- /dev/null
+++ b/tests/unistr/test-chr.h
@@ -0,0 +1,103 @@
+/* Test of uN_chr() functions.
+   Copyright (C) 2008-2010 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 Eric Blake and Bruno Haible <bruno@clisp.org>, 2010.  */
+
+int
+main (void)
+{
+  size_t n = 0x100000;
+  UNIT *input = (UNIT *) malloc (n * sizeof (UNIT));
+  ASSERT (input);
+
+  input[0] = 'a';
+  input[1] = 'b';
+  U_SET (input + 2, 'c', 1024);
+  U_SET (input + 1026, 'd', n - 1028);
+  input[n - 2] = 'e';
+  input[n - 1] = 'a';
+
+  /* Basic behavior tests.  */
+  ASSERT (U_CHR (input, n, 'a') == input);
+
+  ASSERT (U_CHR (input, 0, 'a') == NULL);
+  ASSERT (U_CHR (zerosize_ptr (), 0, 'a') == NULL);
+
+  ASSERT (U_CHR (input, n, 'b') == input + 1);
+  ASSERT (U_CHR (input, n, 'c') == input + 2);
+  ASSERT (U_CHR (input, n, 'd') == input + 1026);
+
+  ASSERT (U_CHR (input + 1, n - 1, 'a') == input + n - 1);
+  ASSERT (U_CHR (input + 1, n - 1, 'e') == input + n - 2);
+
+  ASSERT (U_CHR (input, n, 'f') == NULL);
+  ASSERT (U_CHR (input, n, '\0') == NULL);
+
+  /* Check that a very long haystack is handled quickly if the byte is
+     found near the beginning.  */
+  {
+    size_t repeat = 10000;
+    for (; repeat > 0; repeat--)
+      {
+        ASSERT (U_CHR (input, n, 'c') == input + 2);
+      }
+  }
+
+  /* Alignment tests.  */
+  {
+    int i, j;
+    for (i = 0; i < 32; i++)
+      {
+        for (j = 0; j < 128; j++)
+          input[i + j] = j;
+        for (j = 0; j < 128; j++)
+          {
+            ASSERT (U_CHR (input + i, 128, j) == input + i + j);
+          }
+      }
+  }
+
+  /* Check that uN_chr() does not read past the first occurrence of the
+     byte being searched.  */
+  {
+    char *page_boundary = (char *) zerosize_ptr ();
+
+    if (page_boundary != NULL)
+      {
+        for (n = 1; n <= 500 / sizeof (UNIT); n++)
+          {
+            UNIT *mem = (UNIT *) (page_boundary - n * sizeof (UNIT));
+            U_SET (mem, 'X', n);
+            ASSERT (U_CHR (mem, n, 'U') == NULL);
+
+            {
+              size_t i;
+
+              for (i = 0; i < n; i++)
+                {
+                  mem[i] = 'U';
+                  ASSERT (U_CHR (mem, 4000, 'U') == mem + i);
+                  mem[i] = 'X';
+                }
+            }
+          }
+      }
+  }
+
+  free (input);
+
+  return 0;
+}

new file mode 100644
--- /dev/null
+++ b/tests/unistr/test-u8-chr.c
@@ -0,0 +1,31 @@
+/* Test of u8_chr() 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 <stdlib.h>
+
+#include "zerosize-ptr.h"
+#include "macros.h"
+
+#define UNIT uint8_t
+#define U_CHR u8_chr
+#define U_SET u8_set
+#include "test-chr.h"