From 643f2acf16e25fa94aee29ed8df048717b69a81e Mon Sep 17 00:00:00 2001
From: Brian Ford <btford@umich.edu>
Date: Fri, 20 Feb 2015 15:24:55 -0800
Subject: [PATCH] feat(bindPromiseFn): add bindPromiseFn method

Closes #49
---
 karma.conf.js     |  2 +-
 test/util.js      |  3 +++
 test/zone.spec.js | 26 ++++++++++++++++++++++++++
 zone.js           | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 76 insertions(+), 1 deletion(-)

diff --git a/karma.conf.js b/karma.conf.js
index 0fa8cb720..e0a6f62c4 100644
--- a/karma.conf.js
+++ b/karma.conf.js
@@ -4,10 +4,10 @@ module.exports = function (config) {
   config.set({
     basePath: '',
     files: [
+      'test/util.js',
       'zone.js',
       '*-zone.js',
       //'test/lib/brick.js',
-      'test/util.js',
       'test/**/*.spec.js',
       {pattern: 'test/assets/**/*.html', watched: true, served: true, included: false}
     ],
diff --git a/test/util.js b/test/util.js
index dfb8d58aa..0deb4c532 100644
--- a/test/util.js
+++ b/test/util.js
@@ -21,3 +21,6 @@ function ifEnvSupports(test, block) {
     }
   };
 };
+
+// useful for testing mocks
+window.__setTimeout = window.setTimeout;
diff --git a/test/zone.spec.js b/test/zone.spec.js
index 1e1aa8cf4..478bab224 100644
--- a/test/zone.spec.js
+++ b/test/zone.spec.js
@@ -140,6 +140,32 @@ describe('Zone', function () {
     });
   });
 
+  describe('bindPromiseFn', function () {
+    var mockPromise = function() {
+      return {
+        then: function (a, b) {
+          window.__setTimeout(a, 0);
+          return mockPromise();
+        }
+      };
+    };
+
+    it('should return a method that returns promises that run in the correct zone', function (done) {
+      zone.fork({ mark: 'a' }).run(function () {
+        var patched = Zone.bindPromiseFn(function() {
+          return mockPromise();
+        });
+
+        patched().then(function () {
+          expect(zone.mark).toBe('a');
+        }).then(function () {
+          expect(zone.mark).toBe('a');
+          done();
+        });
+      });
+    });
+  });
+
 });
 
 function throwError () {
diff --git a/zone.js b/zone.js
index 2f80837b6..b45ce9081 100644
--- a/zone.js
+++ b/zone.js
@@ -221,6 +221,52 @@ Zone.bindArgumentsOnce = function (args) {
   return args;
 };
 
+/*
+ * patch a fn that returns a promise
+ */
+Zone.bindPromiseFn = (function() {
+  // if the browser natively supports Promises, we can just return a native promise
+  if (window.Promise) {
+    return function (delegate) {
+      return function() {
+        var delegatePromise = delegate.apply(this, arguments);
+        if (delegatePromise instanceof Promise) {
+          return delegatePromise;
+        } else {
+          return new Promise(function(resolve, reject) {
+            delegatePromise.then(resolve, reject);
+          });
+        }
+      };
+    };
+  } else {
+    // if the browser does not have native promises, we have to patch each promise instance
+    return function (delegate) {
+      return function () {
+        return patchThenable(delegate.apply(this, arguments));
+      };
+    };
+
+    function patchThenable(thenable) {
+      var then = thenable.then;
+      thenable.then = function () {
+        var args = Zone.bindArguments(arguments);
+        var nextThenable = then.apply(thenable, args);
+        return patchThenable(nextThenable);
+      };
+
+      var ocatch = thenable.catch;
+      thenable.catch = function () {
+        var args = Zone.bindArguments(arguments);
+        var nextThenable = ocatch.apply(thenable, args);
+        return patchThenable(nextThenable);
+      };
+      return thenable;
+    }
+  }
+}());
+
+
 Zone.patchableFn = function (obj, fnNames) {
   fnNames.forEach(function (name) {
     var delegate = obj[name];