def test_readNone(self):
        """
        Calling L{_InputStream.read} with L{None} as an argument returns all
        bytes in the input stream.
        """
        bytes = b"the entire stream"
        d = self._renderAndReturnReaderResult(
            lambda input: input.read(None), bytes)
        d.addCallback(self.assertEqual, bytes)
        return d

        Calling L{_InputStream.read} with L{None} as an argument returns all
        bytes in the input stream.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_wsgi.py