'If the L{FileBodyProducer} is constructed with a file-like object
without either a C{seek} or C{tell} method, its C{length} attribute is
set to C{UNKNOWN_LENGTH}.'

def test_unknownLength(self):

    class HasSeek(object, ):
        def seek(self, offset, whence):
            pass
    class HasTell(object, ):
        def tell(self):
            pass
    producer = FileBodyProducer(HasSeek())
    self.assertEqual(UNKNOWN_LENGTH, producer.length)
    producer = FileBodyProducer(HasTell())
    self.assertEqual(UNKNOWN_LENGTH, producer.length)
