def test_readlinesNegative(self):
        """
        Calling L{_InputStream.readlines} with a negative integer as an
        argument returns a list of all lines from the input.
        """
        bytes = b"red fish\nblue fish\n"
        d = self._renderAndReturnReaderResult(
            lambda input: input.readlines(-1), bytes)
        d.addCallback(self.assertEqual, [b"red fish\n", b"blue fish\n"])
        return d

        Calling L{_InputStream.readlines} with a negative integer as an
        argument returns a list of all lines from the input.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_wsgi.py