'Calling L{_InputStream.read} a second time returns bytes starting from
the position after the last byte returned by the previous read.'

def test_readTwice(self):

    bytes = 'some    bytes,    hello'
    def read(input):
        input.read(3)
        return input.read()
    d = self._renderAndReturnReaderResult(read, bytes)
    d.addCallback(self.assertEqual, bytes[3:])
    return d
