def test_headResponse(self):
        """
        If the response is to a HEAD request, no body is expected, the body
        callback is not invoked, and the I{Content-Length} header is passed to
        the header callback.
        """
        request = Request(b'HEAD', b'/', _boringHeaders, None)
        status = b'HTTP/1.1 200 OK\r\n'
        response = (
            b'Content-Length: 10\r\n'
            b'\r\n')
        header = self._noBodyTest(request, status, response)
        self.assertEqual(header, {b'Content-Length': b'10'})

        If the response is to a HEAD request, no body is expected, the body
        callback is not invoked, and the I{Content-Length} header is passed to
        the header callback.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_newclient.py