promise.resolve(promise) === fulfillment

browser/rsvp.js

@@ -369,7 +369,13 @@ define("rsvp/promise",
     var config = __dependency1__.config;
     var EventTarget = __dependency2__.EventTarget;
 
-    var noop = function() {};
+    function objectOrFunction(x) {
+      return isFunction(x) || (typeof x === "object" && x !== null);
+    }
+
+    function isFunction(x){
+      return typeof x === "function";
+    }
 
     var Promise = function(resolver) {
       var promise = this,
@@ -407,7 +413,7 @@ define("rsvp/promise",
     };
 
     var invokeCallback = function(type, promise, callback, event) {
-      var hasCallback = typeof callback === 'function',
+      var hasCallback = isFunction(callback),
           value, error, succeeded, failed;
 
       if (hasCallback) {
@@ -423,7 +429,7 @@ define("rsvp/promise",
         succeeded = true;
       }
 
-      if (value && typeof value.then === 'function') {
+      if (objectOrFunction(value) && isFunction(value.then)) {
         value.then(function(value) {
           resolve(promise, value);
         }, function(error) {
@@ -473,7 +479,9 @@ define("rsvp/promise",
     EventTarget.mixin(Promise.prototype);
 
     function resolve(promise, value) {
-      if (value && typeof value.then === 'function') {
+      if (value && (value === promise) || (objectOrFunction(value) && isFunction(value.promise) && value.promise() === promise)) {
+        fulfill(promise, value);
+      } else if (objectOrFunction(value) && isFunction(value.then)) {
         value.then(function(val) {
           resolve(promise, val);
         }, function(val) {

browser/rsvp/promise.amd.js

@@ -5,7 +5,13 @@ define(
     var config = __dependency1__.config;
     var EventTarget = __dependency2__.EventTarget;
 
-    var noop = function() {};
+    function objectOrFunction(x) {
+      return isFunction(x) || (typeof x === "object" && x !== null);
+    }
+
+    function isFunction(x){
+      return typeof x === "function";
+    }
 
     var Promise = function(resolver) {
       var promise = this,
@@ -43,7 +49,7 @@ define(
     };
 
     var invokeCallback = function(type, promise, callback, event) {
-      var hasCallback = typeof callback === 'function',
+      var hasCallback = isFunction(callback),
           value, error, succeeded, failed;
 
       if (hasCallback) {
@@ -59,7 +65,7 @@ define(
         succeeded = true;
       }
 
-      if (value && typeof value.then === 'function') {
+      if (objectOrFunction(value) && isFunction(value.then)) {
         value.then(function(value) {
           resolve(promise, value);
         }, function(error) {
@@ -109,7 +115,9 @@ define(
     EventTarget.mixin(Promise.prototype);
 
     function resolve(promise, value) {
-      if (value && typeof value.then === 'function') {
+      if (value && (value === promise) || (objectOrFunction(value) && isFunction(value.promise) && value.promise() === promise)) {
+        fulfill(promise, value);
+      } else if (objectOrFunction(value) && isFunction(value.then)) {
         value.then(function(val) {
           resolve(promise, val);
         }, function(val) {

lib/rsvp/promise.js

 import { config } from "rsvp/config";
 import { EventTarget } from "rsvp/events";
 
+function objectOrFunction(x) {
+  return isFunction(x) || (typeof x === "object" && x !== null);
+}
+
+function isFunction(x){
+  return typeof x === "function";
+}
+
 var Promise = function(resolver) {
   var promise = this,
   resolved = false;
@@ -37,7 +45,7 @@ var Promise = function(resolver) {
 };
 
 var invokeCallback = function(type, promise, callback, event) {
-  var hasCallback = typeof callback === 'function',
+  var hasCallback = isFunction(callback),
       value, error, succeeded, failed;
 
   if (hasCallback) {
@@ -53,7 +61,7 @@ var invokeCallback = function(type, promise, callback, event) {
     succeeded = true;
   }
 
-  if (value && typeof value.then === 'function') {
+  if (objectOrFunction(value) && isFunction(value.then)) {
     value.then(function(value) {
       resolve(promise, value);
     }, function(error) {
@@ -103,7 +111,9 @@ Promise.prototype = {
 EventTarget.mixin(Promise.prototype);
 
 function resolve(promise, value) {
-  if (value && typeof value.then === 'function') {
+  if (value && (value === promise) || (objectOrFunction(value) && isFunction(value.promise) && value.promise() === promise)) {
+    fulfill(promise, value);
+  } else if (objectOrFunction(value) && isFunction(value.then)) {
     value.then(function(val) {
       resolve(promise, val);
     }, function(val) {

tests/extension-tests.js

 /*global RSVP, describe, specify, it, assert */
 describe("RSVP extensions", function() {
+  describe("self fulfillment", function(){
+    it("treats self fulfillment as the recursive base case", function(done){
+      var aDefer = new RSVP.defer(),
+      bDefer = new RSVP.defer();
+
+      aDefer.promise.then(function(a){
+        setTimeout(function(){
+          bDefer.resolve(bDefer);
+        }, 1);
+
+        return bDefer.promise;
+      });
+
+      bDefer.promise.then(function(c){
+        done();
+      })
+
+      aDefer.resolve(aDefer.promise);
+    });
+  });
+
   describe("Promise constructor", function() {
     it('should exist and have length 1', function() {
       assert(RSVP.Promise);