add ServerResponse#toJSON()

lib/http.js

@@ -922,6 +922,13 @@ exports.ServerResponse = ServerResponse;
 
 ServerResponse.prototype.statusCode = 200;
 
+ServerResponse.prototype.toJSON = function(){
+  return {
+    statusCode: this.statusCode,
+    headers: this._headers
+  }
+};
+
 function onServerResponseClose() {
   this._httpMessage.emit('close');
 }

test/simple/test-http-response-tojson.js

@@ -0,0 +1,29 @@
+
+var common = require('../common');
+var assert = require('assert');
+var http = require('http');
+
+var server = http.createServer(function(req, res){
+  res.statusCode = 400;
+  res.setHeader('Content-Length', '5');
+  res.setHeader('Content-Type', 'text/plain');
+
+  var obj = JSON.parse(JSON.stringify(res));
+
+  assert.deepEqual(obj, {
+    statusCode: 400,
+    headers: {
+      'content-length': '5',
+      'content-type': 'text/plain'
+    }
+  });
+
+  process.exit(0);
+});
+
+server.listen(common.PORT);
+
+http.get({
+  port: common.PORT,
+  path: '/something'
+});