test: add test for responses to HTTP CONNECT req

See: https://github.com/nodejs/node/pull/6198
PR-URL: https://github.com/nodejs/node/pull/6279
Reviewed-By: Brian White <mscdex@mscdex.net>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/parallel/test-http-connect-req-res.js

@@ -0,0 +1,72 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const http = require('http');
+
+const server = http.createServer(function(req, res) {
+  assert(false);
+});
+server.on('connect', common.mustCall(function(req, socket, firstBodyChunk) {
+  assert.equal(req.method, 'CONNECT');
+  assert.equal(req.url, 'example.com:443');
+  console.error('Server got CONNECT request');
+
+  // It is legal for the server to send some data intended for the client
+  // along with the CONNECT response
+  socket.write(
+    'HTTP/1.1 200 Connection established\r\n' +
+    'Date: Tue, 15 Nov 1994 08:12:31 GMT\r\n' +
+    '\r\n' +
+    'Head'
+  );
+
+  var data = firstBodyChunk.toString();
+  socket.on('data', function(buf) {
+    data += buf.toString();
+  });
+  socket.on('end', function() {
+    socket.end(data);
+  });
+}));
+server.listen(common.PORT, common.mustCall(function() {
+  const req = http.request({
+    port: common.PORT,
+    method: 'CONNECT',
+    path: 'example.com:443'
+  }, function(res) {
+    assert(false);
+  });
+
+  req.on('close', common.mustCall(function() { }));
+
+  req.on('connect', common.mustCall(function(res, socket, firstBodyChunk) {
+    console.error('Client got CONNECT request');
+
+    // Make sure this request got removed from the pool.
+    const name = 'localhost:' + common.PORT;
+    assert(!http.globalAgent.sockets.hasOwnProperty(name));
+    assert(!http.globalAgent.requests.hasOwnProperty(name));
+
+    // Make sure this socket has detached.
+    assert(!socket.ondata);
+    assert(!socket.onend);
+    assert.equal(socket.listeners('connect').length, 0);
+    assert.equal(socket.listeners('data').length, 0);
+
+    var data = firstBodyChunk.toString();
+
+    // test that the firstBodyChunk was not parsed as HTTP
+    assert.equal(data, 'Head');
+
+    socket.on('data', function(buf) {
+      data += buf.toString();
+    });
+    socket.on('end', function() {
+      assert.equal(data, 'HeadRequestEnd');
+      server.close();
+    });
+    socket.end('End');
+  }));
+
+  req.end('Request');
+}));