public function testRuleIsInvalidIfExtensionIsNotInList()
 {
     $this->fakeConfig->SetSectionKey(ConfigSection::UPLOADS, ConfigKeys::UPLOAD_RESERVATION_EXTENSIONS, '.pdf');
     $attachment = new FakeReservationAttachment();
     $attachment->SetExtension('doc');
     $this->series->AddAttachment($attachment);
     $result = $this->validator->Validate($this->series);
     $this->assertFalse($result->IsValid());
 }