From b40848fe1d2eccde3f24e8bb75602ad154537d9d Mon Sep 17 00:00:00 2001
From: Robert Jackson <robert.w.jackson@me.com>
Date: Sat, 25 Oct 2014 15:13:40 -0400
Subject: [PATCH] Add a assertion when watched props are are written to without
 Em.set.

---
 packages/ember-metal/lib/property_get.js      |  4 +++
 .../tests/accessors/mandatory_setters_test.js | 30 +++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/packages/ember-metal/lib/property_get.js b/packages/ember-metal/lib/property_get.js
index a0ae18a4926..fe3317d3085 100644
--- a/packages/ember-metal/lib/property_get.js
+++ b/packages/ember-metal/lib/property_get.js
@@ -81,6 +81,10 @@ var get = function get(obj, keyName) {
     if (Ember.FEATURES.isEnabled('mandatory-setter')) {
       if (hasPropertyAccessors && meta && meta.watching[keyName] > 0) {
         ret = meta.values[keyName];
+
+        if (ret === undefined && keyName in obj && !(keyName in meta.values)) {
+          Ember.assert('You must use Ember.set to set `' + keyName + '` (on `' + obj + '`).');
+        }
       } else {
         ret = obj[keyName];
       }
diff --git a/packages/ember-metal/tests/accessors/mandatory_setters_test.js b/packages/ember-metal/tests/accessors/mandatory_setters_test.js
index 57755fcaaf1..32f633ed443 100644
--- a/packages/ember-metal/tests/accessors/mandatory_setters_test.js
+++ b/packages/ember-metal/tests/accessors/mandatory_setters_test.js
@@ -32,6 +32,22 @@ if (Ember.FEATURES.isEnabled('mandatory-setter')) {
     }, 'You must use Ember.set() to set the `someProp` property (of custom-object) to `foo-bar`.');
   });
 
+  test('should assert if get a watched property (not on the prototype) that is not set by Ember.set', function() {
+    var obj = {
+      toString: function() {
+        return 'custom-object';
+      }
+    };
+
+    watch(obj, 'someProp');
+
+    obj.someProp = 'foo-bar';
+
+    expectAssertion(function() {
+      get(obj, 'someProp');
+    }, 'You must use Ember.set to set `someProp` (on `custom-object`).');
+  });
+
   test('should not assert if set with Ember.set when property is being watched', function() {
     var obj = {
       someProp: null,
@@ -45,6 +61,20 @@ if (Ember.FEATURES.isEnabled('mandatory-setter')) {
 
     equal(get(obj, 'someProp'), 'foo-bar');
   });
+
+  test('prints a helpful assertion if a watched property (not present at watch time) was not set with Ember.set', function() {
+    var obj = {
+      toString: function() {
+        return 'custom-object';
+      }
+    };
+
+    watch(obj, 'someProp');
+    obj.someProp = 'blastix';
+
+    equal(get(obj, 'someProp'), 'blastix');
+  });
+
 } else {
   test('does not assert', function() {
     var obj = {