Prove that Instance.equals() still doesn't work and fix it (#5605)

* Added failing test to prove that #5301 is not fixed yet

* Instance.equals() compares only model and primary key. Fixes #5103

* Instance .equals() PK check accounts for multiple PKs

lib/instance.js

@@ -1011,27 +1011,25 @@ Instance.prototype.decrement = function(fields, options) {
 };
 
 /**
- * Check whether all values of this and `other` Instance are the same
+ * Check whether this and `other` Instance refer to the same row
  *
  * @param {Instance} other
  * @return {Boolean}
  */
 Instance.prototype.equals = function(other) {
-  var result = true;
+  var self = this; 
 
-  if (!other || !other.dataValues) {
+  if (!other || !other.Model) {
     return false;
   }
 
-  Utils._.each(this.dataValues, function(value, key) {
-    if (Utils._.isDate(value) && Utils._.isDate(other.dataValues[key])) {
-      result = result && (value.getTime() === other.dataValues[key].getTime());
-    } else {
-      result = result && (value === other.dataValues[key]);
-    }
-  });
+  if (other.Model !== this.Model) {
+    return false;
+  }
 
-  return result;
+  return Utils._.every(this.Model.primaryKeyAttributes, function(attribute) {
+    return self.get(attribute, {raw: true}) === other.get(attribute, {raw: true});
+  });
 };
 
 /**

test/integration/instance.test.js

@@ -1878,7 +1878,9 @@ describe(Support.getTestDialectTeaser('Instance'), function() {
                     expect(user1.get('Projects')).to.not.exist;
                     expect(user2.get('Projects')).to.exist;
                     expect(user1.equals(user2)).to.be.true;
+                    expect(user2.equals(user1)).to.be.true;
                     expect(user1.equals(user3)).to.not.be.true;
+                    expect(user3.equals(user1)).to.not.be.true;
                   });
                 });
               });