public function testSetAllowedExtensionsFail()
 {
     // .pl (Perl scripts) is not allowed
     $dl2 = new downloader();
     $dl2->setAllowedExtensions(array('jpg' => 'image/jpeg', 'pl' => 'application/x-perl'));
     $this->assertTrue($dl2->areErrors());
     // one invalid extension will invalidate the entire list
     $this->assertFalse($dl2->checkExtension('jpg'));
     $this->assertFalse($dl2->checkExtension('jpeg'));
     $this->assertFalse($dl2->checkExtension('pl'));
 }