Make subscribe/unsubscribe/sendMessage return Promises that fire on RPC return.

static/cosmopolite.js

@@ -84,22 +84,26 @@ Cosmopolite.prototype.subscribe = function(subject, messages, keys) {
   if (!this.ready_) {
     throw "cosmopolite: not ready";
   }
+
+  return new Promise(function(resolve, reject) {
     keys = keys || [];
     if (subject in this.subscriptions_) {
       console.log(
         this.loggingPrefix_(),
         'not sending duplication subscription request for subject:', subject);
-    return;
+      resolve();
     }
     this.subscriptions_[subject] = {
       'messages': [],
       'keys': {},
     };
-  this.sendRPC_('subscribe', {
+    var args = {
       'subject': subject,
       'messages': messages,
       'keys': keys,
-  });
+    };
+    this.sendRPC_('subscribe', args, resolve);
+  }.bind(this));
 };
 
 /**
@@ -114,10 +118,14 @@ Cosmopolite.prototype.unsubscribe = function(subject) {
   if (!this.ready_) {
     throw "cosmopolite: not ready";
   }
+
+  return new Promise(function(resolve, reject) {
     delete this.subscriptions_[subject];
-  this.sendRPC_('unsubscribe', {
+    var args = {
       'subject': subject,
-  });
+    }
+    this.sendRPC_('unsubscribe', args, resolve);
+  }.bind(this));
 };
 
 /**
@@ -131,6 +139,8 @@ Cosmopolite.prototype.sendMessage = function(subject, message, key) {
   if (!this.ready_) {
     throw "cosmopolite: not ready";
   }
+
+  return new Promise(function(resolve, reject) {
     var args = {
       'subject':           subject,
       'message':           JSON.stringify(message),
@@ -139,7 +149,8 @@ Cosmopolite.prototype.sendMessage = function(subject, message, key) {
     if (key) {
       args['key'] = key;
     }
-  this.sendRPC_('sendMessage', args);
+    this.sendRPC_('sendMessage', args, resolve);
+  }.bind(this));
 };
 
 /**

static/test.js

@@ -174,6 +174,47 @@ asyncTest('Complex object', function() {
   var cosmo = new Cosmopolite(callbacks, null, randstring());
 });
 
+asyncTest('sendMessage Promise', function() {
+  expect(1);
+
+  var subject = randstring();
+  var message = randstring();
+
+  var callbacks = {
+    'onReady': function() {
+      cosmo.sendMessage(subject, message).then(function() {
+        ok(true, 'sendMessage Promise fulfilled');
+        cosmo.shutdown();
+        start();
+      });
+    },
+  };
+
+  var cosmo = new Cosmopolite(callbacks, null, randstring());
+});
+
+asyncTest('subscribe/unsubscribe Promise', function() {
+  expect(2);
+
+  var subject = randstring();
+  var message = randstring();
+
+  var callbacks = {
+    'onReady': function() {
+      cosmo.subscribe(subject).then(function() {
+        ok(true, 'subscribe Promise fulfilled');
+        cosmo.unsubscribe(subject).then(function() {
+          ok(true, 'unsubscribe Promise fulfilled');
+          cosmo.shutdown();
+          start();
+        });
+      });
+    },
+  };
+
+  var cosmo = new Cosmopolite(callbacks, null, randstring());
+});
+
 
 module('dev_appserver only');