diff --git a/.jshintrc b/.jshintrc
index 698262e..81fbe5f 100644
--- a/.jshintrc
+++ b/.jshintrc
@@ -11,6 +11,7 @@
     "before",
     "after",
     "should",
+    "rewire",
     "$"
   ],
 
diff --git a/Makefile b/Makefile
index 1ea54fb..5b1c160 100644
--- a/Makefile
+++ b/Makefile
@@ -2,8 +2,10 @@ SRC := libs controllers plugins models
 TESTS = $(shell find test -type f -name "*.js")
 TESTTIMEOUT = 5000
 REPORTER = spec
+JSCOVERAGE = ./node_modules/visionmedia-jscoverage/jscoverage
 
 test:
+	@npm install
 	@if ! test -f config.js; then \
 		cp config.default.js config.js; \
 	fi
@@ -16,7 +18,7 @@ test-dot:
 cov:
 	@for dir in $(SRC); do \
 		mv $$dir $$dir.bak; \
-		jscoverage --encoding=utf-8 $$dir.bak $$dir; \
+		$(JSCOVERAGE) --encoding=utf-8 $$dir.bak $$dir; \
 	done
 
 cov-clean:
@@ -29,9 +31,4 @@ test-cov: cov
 	@-$(MAKE) test REPORTER=html-cov > coverage.html
 	@$(MAKE) cov-clean
 
-test-for:
-	@for dir in $(SRC); do \
-		echo $$dir; \
-	done
-
 .PHONY: test test-cov test-dot cov cov-clean
diff --git a/controllers/at.js b/controllers/at.js
index 093c522..9b253e4 100644
--- a/controllers/at.js
+++ b/controllers/at.js
@@ -34,7 +34,7 @@ function searchUsers(text, callback) {
 }
 
 function sendMessageToMentionUsers(text, topicId, authorId, callback) {
-  exports.searchUsers(text, function (err, users) {
+  searchUsers(text, function (err, users) {
     if (err || !users || users.length === 0) {
       return callback && callback(err);
     }
@@ -58,7 +58,7 @@ function sendMessageToMentionUsers(text, topicId, authorId, callback) {
 }
 
 function linkUsers(text, callback) {
-  exports.searchUsers(text, function (err, users) {
+  searchUsers(text, function (err, users) {
     if (err) {
       return callback(err);
     }
@@ -70,6 +70,5 @@ function linkUsers(text, callback) {
   });
 }
 
-exports.searchUsers = searchUsers;
 exports.send_at_message = exports.sendMessageToMentionUsers = sendMessageToMentionUsers;
 exports.link_at_who = exports.linkUsers = linkUsers;
diff --git a/package.json b/package.json
index 9d3a5b7..043bc3b 100644
--- a/package.json
+++ b/package.json
@@ -16,7 +16,9 @@
   },
   "devDependencies": {
     "should": ">=0.6.0",
-    "mocha": ">=0.14.1"
+    "mocha": ">=0.14.1",
+    "rewire": ">=0.2.0",
+    "visionmedia-jscoverage": ">=1.0.0"
   },
   "scripts": {
     "test": "make test"
diff --git a/test/controllers/at.js b/test/controllers/at.js
index 550142a..fe11e84 100644
--- a/test/controllers/at.js
+++ b/test/controllers/at.js
@@ -7,9 +7,8 @@
 /**
  * Module dependencies.
  */
-
+var rewire = require("rewire");
 var should = require('should');
-var mentionUser = require('../../controllers/at');
 var Message = require('../../controllers/message');
 var config = require('../../config').config;
 var createUsers = require('../support/create_test_users').createUsers;
@@ -30,9 +29,10 @@ describe('controllers/at.js', function () {
     @<a href="/user/testuser2">testuser2</a>@<a href="/user/testuser1">testuser1</a>23 oh my god';
 
   describe('searchUsers()', function () {
-
+    var mentionUser = rewire('../../controllers/at');
+    var searchUsers = mentionUser.__get__('searchUsers');
     it('should found 3 test users', function (done) {
-      mentionUser.searchUsers(text, function (err, users) {
+      searchUsers(text, function (err, users) {
         should.not.exist(err);
         should.exist(users);
         users.should.length(3);
@@ -45,7 +45,7 @@ describe('controllers/at.js', function () {
     });
 
     it('should found 0 user in text', function (done) {
-      mentionUser.searchUsers('no users match in text @ @@@@ @ @@@ @哈哈 @ testuser1', function (err, users) {
+      searchUsers('no users match in text @ @@@@ @ @@@ @哈哈 @ testuser1', function (err, users) {
         should.not.exist(err);
         should.exist(users);
         users.should.length(0);
@@ -54,7 +54,7 @@ describe('controllers/at.js', function () {
     });
 
     it('should found 0 user in db', function (done) {
-      mentionUser.searchUsers('@testuser123 @suqian2012 @ testuser1 no users match in db @ @@@@ @ @@@', 
+      searchUsers('@testuser123 @suqian2012 @ testuser1 no users match in db @ @@@@ @ @@@', 
       function (err, users) {
         should.not.exist(err);
         should.exist(users);
@@ -65,6 +65,7 @@ describe('controllers/at.js', function () {
   });
 
   describe('linkUsers()', function () {
+    var mentionUser = rewire('../../controllers/at');
     it('should link all mention users', function (done) {
       mentionUser.linkUsers(text, function (err, text2) {
         should.not.exist(err);
@@ -74,18 +75,17 @@ describe('controllers/at.js', function () {
     });
 
     describe('mock searchUsers() error', function () {
-      var searchUsers = mentionUser.searchUsers;
       before(function () {
-        mentionUser.searchUsers = function () {
-          var callback = arguments[arguments.length - 1];
-          process.nextTick(function () {
-            callback(new Error('mock searchUsers() error'));
-          });
-        };
-      });
-      after(function () {
-        mentionUser.searchUsers = searchUsers;
+        mentionUser.__set__({
+          searchUsers: function () {
+            var callback = arguments[arguments.length - 1];
+            process.nextTick(function () {
+              callback(new Error('mock searchUsers() error'));
+            });
+          }
+        });
       });
+
       it('should return error', function (done) {
         mentionUser.linkUsers(text, function (err, text2) {
           should.exist(err);
@@ -98,6 +98,7 @@ describe('controllers/at.js', function () {
   });
 
   describe('sendMessageToMentionUsers()', function () {
+    var mentionUser = rewire('../../controllers/at');
     it('should send message to all mention users', function (done) {
       mentionUser.sendMessageToMentionUsers(text, '4fb9db9c1dc2160000000005', '4fcae41e1eb86c0000000003', 
       function (err) {
diff --git a/test/support/http.js b/test/support/http.js
index 212f9c9..bbd3825 100644
--- a/test/support/http.js
+++ b/test/support/http.js
@@ -23,7 +23,7 @@ express.HTTPServer.prototype.request = function (address) {
   return new Request(this, address);
 };
 
-if (connect) {
+if (connect && connect.HTTPServer) {
   connect.HTTPServer.prototype.request = express.HTTPServer.prototype.request;
 }