fix correct previous value (#7186)

changelog.md

+# Future
+- [FIXED] `previous` method gave wrong value back [#7189](https://github.com/sequelize/sequelize/pull/7189)
+
 # 3.30.1
 # 3.30.1
 - [FIXED] `sourceKey` FOR `hasMany` now also works if a `where` was specified in an `include` [#7141](https://github.com/sequelize/sequelize/issues/7141)
 - [FIXED] `sourceKey` FOR `hasMany` now also works if a `where` was specified in an `include` [#7141](https://github.com/sequelize/sequelize/issues/7141)
 - [CHANGED] Updated deprecated `node-uuid` package to `uuid` [#7148](https://github.com/sequelize/sequelize/pull/7148)
 - [CHANGED] Updated deprecated `node-uuid` package to `uuid` [#7148](https://github.com/sequelize/sequelize/pull/7148)

lib/instance.js

@@ -158,11 +158,12 @@ Instance.prototype.getDataValue = function(key) {
  * @param {any} value
  * @param {any} value
  */
  */
 Instance.prototype.setDataValue = function(key, value) {
 Instance.prototype.setDataValue = function(key, value) {
-  var originalValue = this._previousDataValues[key];
+  var originalValue = this.dataValues[key];
   if (!Utils.isPrimitive(value) || value !== originalValue) {
   if (!Utils.isPrimitive(value) || value !== originalValue) {
     this.changed(key, true);
     this.changed(key, true);
   }
   }
 
 
+  this._previousDataValues[key] = originalValue;
   this.dataValues[key] = value;
   this.dataValues[key] = value;
 };
 };
 
 

test/unit/instance/previous.test.js

+'use strict';
+
+/* jshint -W030 */
+var chai = require('chai')
+  , expect = chai.expect
+  , Support   = require(__dirname + '/../support')
+  , DataTypes = require(__dirname + '/../../../lib/data-types')
+  , current   = Support.sequelize;
+
+describe(Support.getTestDialectTeaser('Instance'), function () {
+  describe('previous', function () {
+    it('should return correct previous value', function () {
+      var Model = current.define('Model', {
+          text: {
+            type: DataTypes.STRING,
+            get: function (name) {
+              return this.getDataValue(name);
+            },
+            set: function (value, name) {
+              this.setDataValue(name, value);
+            }
+          }
+        })
+        , instance
+        , shouldBeEmpty
+        , shouldBeA;
+
+      instance = Model.build({ text: 'a' }, {
+        isNewRecord: false
+      });
+
+      shouldBeEmpty = instance.previous('text');
+
+      instance.set('text', 'b');
+
+      shouldBeA = instance.previous('text');
+
+      expect(shouldBeEmpty).to.be.not.ok;
+      expect(shouldBeA).to.be.equal('a');
+    });
+  });
+});