'L{DigestCredentialFactory.getChallenge} can issue a challenge even if
the L{Request} it is passed returns L{None} from C{getClientIP}.'

def test_getChallengeWithoutClientIP(self):

    request = self.makeRequest('GET', None)
    challenge = self.credentialFactory.getChallenge(request)
    self.assertEqual(challenge['qop'], 'auth')
    self.assertEqual(challenge['realm'], 'test    realm')
    self.assertEqual(challenge['algorithm'], 'md5')
    self.assertIn('nonce', challenge)
    self.assertIn('opaque', challenge)
