fix cnodejs#237 if topic not exists, do not modified it.

Author: fengmk2

package.json

@@ -20,6 +20,7 @@
     "loader": "0.0.5"
   },
   "devDependencies": {
+    "supertest": "*",
     "should": "*",
     "mocha": "*",
     "rewire": "*",

proxy/topic.js

@@ -172,7 +172,7 @@ exports.getFullTopic = function (id, callback) {
  */
 exports.updateLastReply = function (topicId, replyId, callback) {
   Topic.findOne({_id: topicId}, function (err, topic) {
-    if (err) {
+    if (err || !topic) {
       return callback(err);
     }
     topic.last_reply = replyId;

test/proxy/topic.js

@@ -17,6 +17,16 @@ describe('proxy/topic.js', function () {
     });
   });
 
+  describe('updateLastReply()', function () {
+    it('should update a topic reply count success when topic not exists', function (done) {
+      Topic.updateLastReply('aaaaaaaaaaaaaaaaaaaaaaaa', 'aaaaaaaaaaaaaaaaaaaaaaaa', function (err, result) {
+        should.not.exist(err);
+        should.not.exist(result);
+        done();
+      });
+    });
+  });
+
   describe('newAndSave', function () {
     it('should ok', function (done) {
       Topic.newAndSave('title', 'content', user._id, function (err, topic) {