def test_explicitly_send_headers(self): req = self.make_request('GET', '/') resp = Response(req) self.writer.drain.return_value = () buf = b'' def append(data): nonlocal buf buf += data self.writer.write.side_effect = append resp.send_headers() self.loop.run_until_complete(resp.write_eof()) txt = buf.decode('utf8') self.assertRegex(txt, 'HTTP/1.1 200 OK\r\nCONTENT-LENGTH: 0\r\n' 'CONNECTION: keep-alive\r\n' 'DATE: .+\r\nSERVER: .+\r\n\r\n')