diff --git a/js-jest/src/gilded_rose.js b/js-jest/src/gilded_rose.js
index dc571818..e83ae86b 100644
--- a/js-jest/src/gilded_rose.js
+++ b/js-jest/src/gilded_rose.js
@@ -16,17 +16,7 @@ class RegularItem extends Item {
     const { name, sellIn, quality } = itemProps
     super(name, sellIn, quality)
     this.validateItemProps(itemProps)
-  }
-
-  _privateVar = 0
-
-  get privateVar () {
-    return this._privateVar
-  }
-
-  set privateVar (value) {
-    console.log(`entered set privateVar with value: ${value}`)
-    this._privateVar = value
+    this.depreciationRate = 1
   }
 
   validateItemProps ({ name, sellIn, quality }) {
@@ -46,6 +36,20 @@ class RegularItem extends Item {
       throw new Error(`[RegularItem.validateItemProps] Invalid itemProps passed to the constructor: ${errors.join(', ')}`)
     }
   }
+
+  updateQuality () {
+    // "Once the sell by date has passed, Quality degrades twice as fast"
+    const adjustedDepreciationRate = this.sellIn < 0
+      ? this.depreciationRate * 2
+      : this.depreciationRate
+
+    // "The Quality of an item is never negative"
+    this.quality = Math.max(0, this.quality - adjustedDepreciationRate)
+
+    // Assuming updateQuality is called only once a day...
+    // "At the end of each day our system lowers both values [quality and sellIn] (...)"
+    this.sellIn--
+  }
 }
 
 class Shop {
@@ -86,9 +90,8 @@ class Shop {
         }
       }
 
-      // Unnecessary decrement of sellIn
-      // "Sulfuras", being a legendary item, never has to be sold or decreases in Quality"
       if (this.items[i].name !== 'Sulfuras, Hand of Ragnaros') {
+        // Decrement sellIn each time updateQuality is called
         this.items[i].sellIn = this.items[i].sellIn - 1
       }
 
diff --git a/js-jest/test/gilded_rose.test.js b/js-jest/test/gilded_rose.test.js
index d615d7a9..2d1b29bb 100644
--- a/js-jest/test/gilded_rose.test.js
+++ b/js-jest/test/gilded_rose.test.js
@@ -9,10 +9,13 @@ const { RegularItem } = require('../src/gilded_rose')
 // })
 
 describe('RegularItem', () => {
-  const getRegularItemFactory = (itemProps) => () => new RegularItem({
+  const mockProperties = {
     name: 'Mock RegularItem',
     sellIn: 5,
-    quality: 25,
+    quality: 25
+  }
+  const getRegularItemFactory = (itemProps) => () => new RegularItem({
+    ...mockProperties,
     ...itemProps
   })
 
@@ -28,4 +31,22 @@ describe('RegularItem', () => {
     expect(getRegularItemFactory({ quality: -1 })).toThrow()
     expect(getRegularItemFactory({ quality: 51 })).toThrow()
   })
+
+  it('[updateQuality] should decrement sellIn by 1 and quality by 1 when sellIn is >= 0', () => {
+    const mockRegularItem = new RegularItem(mockProperties)
+    mockRegularItem.updateQuality()
+    expect(mockRegularItem.quality).toEqual(mockProperties.quality - 1)
+  })
+
+  it('[updateQuality] should decrement sellIn by 1 and quality by 2 when sellIn is < 0', () => {
+    const mockRegularItem = new RegularItem({ ...mockProperties, sellIn: -1 })
+    mockRegularItem.updateQuality()
+    expect(mockRegularItem.quality).toEqual(mockProperties.quality - 2)
+  })
+
+  it('[updateQuality] should not decrement quality to a negative number', () => {
+    const mockRegularItem = new RegularItem({ ...mockProperties, quality: 0, sellIn: -1 })
+    mockRegularItem.updateQuality()
+    expect(mockRegularItem.quality).toBeGreaterThanOrEqual(0)
+  })
 })
diff --git a/js-jest/test/texttest_fixture.js b/js-jest/test/texttest_fixture.js
index d634d3d5..051ac8ee 100644
--- a/js-jest/test/texttest_fixture.js
+++ b/js-jest/test/texttest_fixture.js
@@ -1,5 +1,5 @@
 
-const { Shop, Item, RegularItem } = require('../src/gilded_rose')
+const { Shop, Item } = require('../src/gilded_rose')
 
 const items = [
   new Item('+5 Dexterity Vest', 10, 20),
@@ -15,16 +15,6 @@ const items = [
   new Item('Conjured Mana Cake', 3, 6)
 ]
 
-const mockRegularItem = new RegularItem({
-  name: 'Mock RegularItem',
-  sellIn: 5,
-  quality: 10
-})
-
-console.log('mockRegularItem.privateVar', mockRegularItem.privateVar) // bbarreto_debug
-mockRegularItem.privateVar = 10
-console.log('mockRegularItem.privateVar', mockRegularItem.privateVar) // bbarreto_debug
-
 const days = Number(process.argv[2]) || 2
 const gildedRose = new Shop(items)