'use strict'; const common = require('../common'); const assert = require('assert'); const http = require('http'); const server = http.createServer(); server.on('request', function(req, res) { res.writeHead(200, {'foo': 'bar'}); res.flushHeaders(); res.flushHeaders(); // Should be idempotent. }); server.listen(0, common.localhostIPv4, function() { const req = http.request({ method: 'GET', host: common.localhostIPv4, port: this.address().port, }, onResponse); req.end(); function onResponse(res) { assert.equal(res.headers['foo'], 'bar'); res.destroy(); server.close(); } });