def test_statusCodeRequestedRangeNotSatisfiable(self):
        """
        If a range is syntactically invalid due to the start being greater than
        the end, the range header is ignored (the request is responded to as if
        it were not present).
        """
        self.request.requestHeaders.addRawHeader(b'range', b'bytes=20-13')
        self.resource.render(self.request)
        self.assertEqual(self.request.responseCode, http.OK)
        self.assertEqual(b''.join(self.request.written), self.payload)
        self.assertEqual(
            self.request.responseHeaders.getRawHeaders(b'content-length')[0],
            intToBytes(len(self.payload)))

        If a range is syntactically invalid due to the start being greater than
        the end, the range header is ignored (the request is responded to as if
        it were not present).
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_static.py