function test_config_value()
 {
     // default value
     $this->assertFalse(config_value('BIBTEXBROWSER_NO_DEFAULT'));
     // setting to true
     bibtexbrowser_configure('BIBTEXBROWSER_NO_DEFAULT', true);
     $this->assertTrue(config_value('BIBTEXBROWSER_NO_DEFAULT'));
     ob_start();
     default_message();
     $this->assertEquals('', ob_get_flush());
     // setting to false
     bibtexbrowser_configure('BIBTEXBROWSER_NO_DEFAULT', false);
     $this->assertFalse(config_value('BIBTEXBROWSER_NO_DEFAULT'));
     ob_start();
     default_message();
     $this->assertContains('Congratulations', ob_get_flush());
 }
   /** @nodoc */
   function default_message()
   {
       if (config_value('BIBTEXBROWSER_NO_DEFAULT') == true) {
           return;
       }
       ?>
 <div id="bibtexbrowser_message">
 Congratulations! bibtexbrowser is correctly installed!<br/>
 Now you have to pass the name of the bibtex file as parameter (e.g. bibtexbrowser.php?bib=mybib.php)<br/>
 You may browse:<br/>
 <?php 
       foreach (glob("*.bib") as $bibfile) {
           $url = "?bib=" . $bibfile;
           echo '<a href="' . $url . '" rel="nofollow">' . $bibfile . '</a><br/>';
       }
       echo "</div>";
   }