only save new sessions if populated

closes koajs#17

Author: jonathanong

Makefile

@@ -2,8 +2,7 @@ test:
 	@NODE_ENV=test ./node_modules/.bin/mocha \
 		--require should \
 		--harmony-generators \
-		--reporter spec \
-		--bail
+		--reporter spec
 
 clean:
 	@rm -rf node_modules

index.js

@@ -69,6 +69,9 @@ module.exports = function(opts){
     // remove
     if (false === sess) return this.cookies.set(key, '', opts);
 
+    // do nothing if new and not populated
+    if (!json && !sess.length) return;
+
     // save
     if (sess.changed(json)) sess.save();
   }
@@ -124,6 +127,19 @@ Session.prototype.changed = function(prev){
   return this._json != prev;
 };
 
+/**
+ * Return how many values there are in the session object.
+ * Used to see if it's "populated".
+ * Aliased as `.populated` because why not.
+ *
+ * @return {Number}
+ * @api public
+ */
+
+Session.prototype.__defineGetter__('length', function(){
+  return Object.keys(this.toJSON()).length;
+});
+
 /**
  * Save session changes by
  * performing a Set-Cookie.

test.js

@@ -12,6 +12,7 @@ describe('Koa Session', function(){
         app.keys = ['a', 'b'];
         app.use(session());
         app.use(function *(){
+          this.session.message = 'hi';
           this.body = this.session;
         });
 
@@ -26,7 +27,8 @@ describe('Koa Session', function(){
         var app = koa();
         app.use(session());
         app.use(function *(){
-          this.session;
+          this.session.message = 'hi';
+          this.body = this.session;
         });
 
         request(app.listen())
@@ -44,6 +46,7 @@ describe('Koa Session', function(){
           signed: false
         }));
         app.use(function *(){
+          this.session.message = 'hi';
           this.body = this.session;
         });
 
@@ -97,7 +100,24 @@ describe('Koa Session', function(){
       })
     })
 
-    describe('when accessed', function(done){
+    describe('when accessed and not populated', function(done){
+      it('should not Set-Cookie', function(done) {
+        var app = App();
+        app.use(function *(){
+          this.session;
+          this.body = 'greetings';
+        })
+        request(app.listen())
+        .get('/')
+        .expect(200, function(err, res){
+          if (err) return done(err);
+          res.header.should.not.have.property('set-cookie');
+          done();
+        })
+      })
+    })
+
+    describe('when populated', function(done){
       it('should Set-Cookie', function(done){
         var app = App();
         app.use(function *(){
@@ -115,17 +135,16 @@ describe('Koa Session', function(){
         })
       })
 
-      it('should not set .isNew', function(done){
+      it('should not Set-Cookie', function(done){
         var app = App();
         app.use(function *(){
           this.body = this.session;
         })
         request(app.listen())
         .get('/')
-        .expect('Set-Cookie', /koa:sess/)
         .expect(200, function(err, res){
           if (err) return done(err);
-          res.header['set-cookie'].should.not.match(/isNew/);
+          res.header.should.not.have.property('set-cookie');
           done();
         })
       })
@@ -212,6 +231,23 @@ describe('Koa Session', function(){
     })
 
     describe('{}', function(){
+      it('should not Set-Cookie', function(done){
+        var app = App();
+        app.use(function *(){
+          this.session = {};
+          this.body = 'asdf';
+        })
+        request(app.listen())
+        .get('/')
+        .expect(200, function(err, res){
+          if (err) return done(err);
+          res.header.should.not.have.property('set-cookie');
+          done();
+        });
+      })
+    })
+
+    describe('{a: b}', function(){
       it('should create a session', function(done){
         var app = App();
         app.use(function *(){