'Ensure cooperative reader supports iterator backends too'

def test_cooperative_reader_of_iterator_stop_iteration_err(self):

    reader = utils.CooperativeReader([(l * 3) for l in ''])
    chunks = []
    while True:
        chunks.append(reader.read(3))
        if (chunks[(-1)] == ''):
            break
    meat = ''.join(chunks)
    self.assertEqual('', meat)
