[test] Add core `test-http-server-multiheaders` test

Modifications:

  * make client connect to `PROXY_PORT` instead of `PORT`

test/core/simple/test-http-server-multiheaders.js

+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+// Verify that the HTTP server implementation handles multiple instances
+// of the same header as per RFC2616: joining the handful of fields by ', '
+// that support it, and dropping duplicates for other fields.
+
+var common = require('../common');
+var assert = require('assert');
+var http = require('http');
+
+var srv = http.createServer(function(req, res) {
+  assert.equal(req.headers.accept, 'abc, def, ghijklmnopqrst');
+  assert.equal(req.headers.host, 'foo');
+  assert.equal(req.headers['x-foo'], 'bingo');
+  assert.equal(req.headers['x-bar'], 'banjo, bango');
+
+  res.writeHead(200, {'Content-Type' : 'text/plain'});
+  res.end('EOF');
+
+  srv.close();
+});
+
+srv.listen(common.PORT, function() {
+  http.get({
+    host: 'localhost',
+    port: common.PROXY_PORT,
+    path: '/',
+    headers: [
+      ['accept', 'abc'],
+      ['accept', 'def'],
+      ['Accept', 'ghijklmnopqrst'],
+      ['host', 'foo'],
+      ['Host', 'bar'],
+      ['hOst', 'baz'],
+      ['x-foo', 'bingo'],
+      ['x-bar', 'banjo'],
+      ['x-bar', 'bango']
+    ]
+  });
+});