--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,8 @@
 2007-04-13  Bruno Haible  <bruno@clisp.org>
 
+	* modules/fbufmode-tests: New file.
+	* tests/test-fbufmode.c: New file.
+
 	* modules/fbufmode: New file.
 	* lib/fbufmode.h: New file.
 	* lib/fbufmode.c: New file.

new file mode 100644
--- /dev/null
+++ b/modules/fbufmode-tests
@@ -0,0 +1,11 @@
+Files:
+tests/test-fbufmode.c
+
+Depends-on:
+
+configure.ac:
+
+Makefile.am:
+TESTS += test-fbufmode
+check_PROGRAMS += test-fbufmode
+

new file mode 100644
--- /dev/null
+++ b/tests/test-fbufmode.c
@@ -0,0 +1,67 @@
+/* Test of fbufmode() function.
+   Copyright (C) 2007 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 2, 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.  */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2007.  */
+
+#include <config.h>
+
+#include "fbufmode.h"
+
+#include <stdlib.h>
+
+#define ASSERT(expr) if (!(expr)) abort ();
+
+#define TESTFILE "t-fbufmode.tmp"
+
+int
+main ()
+{
+  FILE *fp;
+  char buf[5];
+
+  /* Create a file with some contents.  */
+  fp = fopen (TESTFILE, "w");
+  if (fp == NULL)
+    goto skip;
+  if (fwrite ("foobarsh", 1, 8, fp) < 8)
+    goto skip;
+  if (fclose (fp))
+    goto skip;
+
+  /* Open it for reading.  */
+  fp = fopen (TESTFILE, "r");
+
+  if (setvbuf (fp, NULL, _IONBF, 0))
+    goto skip;
+  ASSERT (fbufmode (fp) == _IONBF);
+
+  if (setvbuf (fp, buf, _IOLBF, 5))
+    goto skip;
+  ASSERT (fbufmode (fp) == _IOLBF);
+
+  if (setvbuf (fp, buf, _IOFBF, 5))
+    goto skip;
+  ASSERT (fbufmode (fp) == _IOFBF);
+
+  fclose (fp);
+
+  return 0;
+
+ skip:
+  fprintf (stderr, "Skipping test: file operations failed.\n");
+  return 77;
+}