'L{Request.processingFailed} when the site has C{displayTracebacks} set
to C{False} does not write out the failure, but give a generic error
message.'

def test_processingFailedNoTraceback(self):

    d = DummyChannel()
    request = server.Request(d, 1)
    request.site = server.Site(resource.Resource())
    request.site.displayTracebacks = False
    fail = failure.Failure(Exception('Oh    no!'))
    request.processingFailed(fail)
    self.assertNotIn('Oh    no!', request.transport.written.getvalue())
    self.assertIn('Processing    Failed', request.transport.written.getvalue())
    self.assertEqual(1, len(self.flushLoggedErrors()))
