add: promise support for sessionStore regenerate

Author: brandonmanke

session/session.js

@@ -165,9 +165,23 @@ defineMethod(Session.prototype, 'destroy', function destroy(fn) {
  */
 
 defineMethod(Session.prototype, 'regenerate', function regenerate(fn) {
-  this.req.sessionStore.regenerate(this.req, fn);
-  return this;
-});
+  if (fn) {
+    this.req.sessionStore.regenerate(this.req, fn)
+    return
+  }
+
+  if (!fn && !global.Promise) {
+    throw new Error('must use callback without promises')
+  }
+
+  var sess = this
+  return new Promise(function (resolve, reject) {
+    sess.req.sessionStore.regenerate(sess.req, function(err) {
+      if (err) reject(err)
+      resolve()
+    })
+  })
+})
 
 /**
  * Helper function for creating a method on a prototype.

test/session.js

@@ -1603,7 +1603,7 @@ describe('session()', function(){
       })
     })
 
-    describe('.regenerate()', function(){
+    describe('.regenerate()', function () {
       it('should destroy/replace the previous session', function(done){
         var server = createServer(null, function (req, res) {
           var id = req.session.id
@@ -1626,6 +1626,66 @@ describe('session()', function(){
           .expect(200, 'false', done)
         });
       })
+
+      describe('with global Promise', function () {
+        beforeEach(function () {
+          global.Promise = Promise
+        })
+
+        afterEach(function () {
+          global.Promise = undefined
+        })
+
+        it('should return Promise without callback', function (done) {
+          var server = createServer(null, function (req, res) {
+            var id = req.session.id
+            req.session.regenerate()
+              .then(function() {
+                res.end(String(req.session.id === id))
+              })
+              .catch(function (err) {
+                if (err) res.statusCode = 500
+              })
+          })
+
+          request(server)
+          .get('/')
+          .expect(shouldSetCookie('connect.sid'))
+          .expect(200, function (err, res) {
+            if (err) return done(err)
+            request(server)
+            .get('/')
+            .set('Cookie', cookie(res))
+            .expect(shouldSetCookie('connect.sid'))
+            .expect(shouldSetCookieToDifferentSessionId(sid(res)))
+            .expect(200, 'false', done)
+          })
+        })
+
+        it('should not return Promise with callback', function(done){
+          var server = createServer(null, function (req, res) {
+            var id = req.session.id
+            var ret = req.session.regenerate(function (err) {
+              if (err) res.statusCode = 500
+              res.statusCode = (ret === undefined) ? 200 : 500
+              res.end(String(req.session.id === id))
+            })
+          })
+
+          request(server)
+          .get('/')
+          .expect(shouldSetCookie('connect.sid'))
+          .expect(200, function (err, res) {
+            if (err) return done(err)
+            request(server)
+            .get('/')
+            .set('Cookie', cookie(res))
+            .expect(shouldSetCookie('connect.sid'))
+            .expect(shouldSetCookieToDifferentSessionId(sid(res)))
+            .expect(200, 'false', done)
+          })
+        })
+      })
     })
 
     describe('.reload()', function () {