def test_headRequest(self):
        """
        L{Data.render} returns an empty response body for a I{HEAD} request.
        """
        data = static.Data(b"foo", "bar")
        request = DummyRequest([''])
        request.method = b'HEAD'
        d = _render(data, request)
        def cbRendered(ignored):
            self.assertEqual(b''.join(request.written), b"")
        d.addCallback(cbRendered)
        return d

        L{Data.render} returns an empty response body for a I{HEAD} request.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_static.py