diff --git a/go/gildedrose/domain/Item.go b/go/gildedrose/domain/Item.go
new file mode 100644
index 00000000..b7140a7f
--- /dev/null
+++ b/go/gildedrose/domain/Item.go
@@ -0,0 +1,6 @@
+package domain
+
+type Item struct {
+	Name            string
+	SellIn, Quality int
+}
diff --git a/go/gildedrose/gildedrose.go b/go/gildedrose/gildedrose.go
index e0f17e12..70ba2477 100644
--- a/go/gildedrose/gildedrose.go
+++ b/go/gildedrose/gildedrose.go
@@ -1,58 +1,96 @@
 package gildedrose
 
-type Item struct {
-	Name            string
-	SellIn, Quality int
+import (
+	"github.com/emilybache/gildedrose-refactoring-kata/gildedrose/domain"
+)
+
+const (
+	AgedBrie            = "Aged Brie"
+	BackstagePasses     = "Backstage passes to a TAFKAL80ETC concert"
+	Sulfuras            = "Sulfuras, Hand of Ragnaros"
+	Conjured            = "Conjured Mana Cake"
+	MaxQuality          = 50
+	MinQuality          = 0
+	SulfurasQuality     = 80
+	Expired             = 0
+	Backstage10Days     = 10
+	Backstage5Days      = 5
+	NormalDegradeRate   = 1
+	ConjuredDegradeRate = 2
+)
+
+func UpdateQuality(items []*domain.Item) {
+	for _, item := range items {
+		updateItem(item)
+		validateQuality(item)
+	}
 }
-
-func UpdateQuality(items []*Item) {
-	for i := 0; i < len(items); i++ {
-
-		if items[i].Name != "Aged Brie" && items[i].Name != "Backstage passes to a TAFKAL80ETC concert" {
-			if items[i].Quality > 0 {
-				if items[i].Name != "Sulfuras, Hand of Ragnaros" {
-					items[i].Quality = items[i].Quality - 1
-				}
-			}
-		} else {
-			if items[i].Quality < 50 {
-				items[i].Quality = items[i].Quality + 1
-				if items[i].Name == "Backstage passes to a TAFKAL80ETC concert" {
-					if items[i].SellIn < 11 {
-						if items[i].Quality < 50 {
-							items[i].Quality = items[i].Quality + 1
-						}
-					}
-					if items[i].SellIn < 6 {
-						if items[i].Quality < 50 {
-							items[i].Quality = items[i].Quality + 1
-						}
-					}
-				}
-			}
-		}
-
-		if items[i].Name != "Sulfuras, Hand of Ragnaros" {
-			items[i].SellIn = items[i].SellIn - 1
-		}
-
-		if items[i].SellIn < 0 {
-			if items[i].Name != "Aged Brie" {
-				if items[i].Name != "Backstage passes to a TAFKAL80ETC concert" {
-					if items[i].Quality > 0 {
-						if items[i].Name != "Sulfuras, Hand of Ragnaros" {
-							items[i].Quality = items[i].Quality - 1
-						}
-					}
-				} else {
-					items[i].Quality = items[i].Quality - items[i].Quality
-				}
-			} else {
-				if items[i].Quality < 50 {
-					items[i].Quality = items[i].Quality + 1
-				}
-			}
+func validateQuality(item *domain.Item) {
+	if item.Name == Sulfuras {
+		if item.Quality != SulfurasQuality {
+			item.Quality = SulfurasQuality
 		}
+		return
+	}
+	if item.Quality > MaxQuality || item.Quality < MinQuality {
+		item.Quality = MinQuality
+	}
+}
+func updateItem(item *domain.Item) {
+	switch item.Name {
+	case AgedBrie:
+		incrementQuality(item)
+	case BackstagePasses:
+		updateBackstagePasses(item)
+	case Sulfuras:
+		// Sulfuras does not change in quality or sell-in
+	case Conjured:
+		degradeQuality(item, ConjuredDegradeRate)
+	default:
+		degradeQuality(item, NormalDegradeRate)
 	}
 
+	if item.Name != Sulfuras {
+		item.SellIn--
+	}
+
+	if item.SellIn < Expired {
+		handleExpiredItem(item)
+	}
+}
+
+func incrementQuality(item *domain.Item) {
+	if item.Quality < MaxQuality {
+		item.Quality++
+	}
+}
+func updateBackstagePasses(item *domain.Item) {
+	incrementQuality(item)
+	if item.SellIn <= Backstage10Days && item.Quality < MaxQuality {
+		item.Quality++
+	}
+	if item.SellIn <= Backstage5Days && item.Quality < MaxQuality {
+		item.Quality++
+	}
+}
+
+func degradeQuality(item *domain.Item, degradeRate int) {
+	if item.Quality > MinQuality {
+		item.Quality -= degradeRate
+	}
+}
+
+func handleExpiredItem(item *domain.Item) {
+	switch item.Name {
+	case AgedBrie:
+		incrementQuality(item)
+	case BackstagePasses:
+		item.Quality = MinQuality
+	case Conjured:
+		degradeQuality(item, ConjuredDegradeRate)
+	case Sulfuras:
+		// Sulfuras does not change in quality or sell-in
+	default:
+		degradeQuality(item, NormalDegradeRate)
+	}
 }
diff --git a/go/gildedrose/gildedrose_test.go b/go/gildedrose/gildedrose_test.go
index ec1bf49b..813f9fca 100644
--- a/go/gildedrose/gildedrose_test.go
+++ b/go/gildedrose/gildedrose_test.go
@@ -1,19 +1,126 @@
 package gildedrose_test
 
 import (
-	"testing"
-
 	"github.com/emilybache/gildedrose-refactoring-kata/gildedrose"
+	"github.com/emilybache/gildedrose-refactoring-kata/gildedrose/domain"
+	"github.com/stretchr/testify/require"
+	"testing"
 )
 
-func Test_Foo(t *testing.T) {
-	var items = []*gildedrose.Item{
-		{"foo", 0, 0},
+func Test_UpdateQuality(t *testing.T) {
+
+	type TestConfig struct {
+		name     string
+		testData []*domain.Item
+		expected domain.Item
 	}
 
-	gildedrose.UpdateQuality(items)
+	for _, tc := range []TestConfig{
+		{
+			name:     "Quality of an item is never less than 0",
+			testData: []*domain.Item{{Name: "Normal Item", SellIn: 10, Quality: 0}},
+			expected: domain.Item{Name: "Normal Item", SellIn: 9, Quality: 0},
+		},
+		{
+			name:     "Quality of an item degrade twice as sellIn date passed",
+			testData: []*domain.Item{{Name: "Normal Item", SellIn: 0, Quality: 10}},
+			expected: domain.Item{Name: "Normal Item", SellIn: -1, Quality: 8},
+		},
+		{
+			name:     "Quality of an item degrade once as sellIn date not passed",
+			testData: []*domain.Item{{Name: "Normal Item", SellIn: 10, Quality: 10}},
+			expected: domain.Item{Name: "Normal Item", SellIn: 9, Quality: 9},
+		},
 
-	if items[0].Name != "fixme" {
-		t.Errorf("Name: Expected %s but got %s ", "fixme", items[0].Name)
+		{
+			name:     "Sell by date not passed, increase AgedBrie quality by 1",
+			testData: []*domain.Item{{Name: gildedrose.AgedBrie, SellIn: 3, Quality: 40}},
+			expected: domain.Item{Name: gildedrose.AgedBrie, SellIn: 2, Quality: 41},
+		},
+		{
+			name:     "Quality of an AgedBrie is never more than 50",
+			testData: []*domain.Item{{Name: gildedrose.AgedBrie, SellIn: 10, Quality: 50}},
+			expected: domain.Item{Name: gildedrose.AgedBrie, SellIn: 9, Quality: 50},
+		},
+		{
+			name:     "Quality of an item upgrade twice as sellIn date passed - AgedBrie",
+			testData: []*domain.Item{{Name: gildedrose.AgedBrie, SellIn: 0, Quality: 40}},
+			expected: domain.Item{Name: gildedrose.AgedBrie, SellIn: -1, Quality: 42},
+		},
+		{
+			name:     "BackstagePasses increase in quality as SellIn approaches - 15 days",
+			testData: []*domain.Item{{Name: gildedrose.BackstagePasses, SellIn: 15, Quality: 20}},
+			expected: domain.Item{Name: gildedrose.BackstagePasses, SellIn: 14, Quality: 21},
+		},
+		{
+			name:     "BackstagePasses increase in quality by 2 when SellIn <= 10",
+			testData: []*domain.Item{{Name: gildedrose.BackstagePasses, SellIn: 10, Quality: 20}},
+			expected: domain.Item{Name: gildedrose.BackstagePasses, SellIn: 9, Quality: 22},
+		},
+		{
+			name:     "BackstagePasses increase in quality by 3 when SellIn <= 5",
+			testData: []*domain.Item{{Name: gildedrose.BackstagePasses, SellIn: 5, Quality: 20}},
+			expected: domain.Item{Name: gildedrose.BackstagePasses, SellIn: 4, Quality: 23},
+		},
+		{
+			name:     "BackstagePasses increase in quality by 3 when SellIn <= 5, quality 49",
+			testData: []*domain.Item{{Name: gildedrose.BackstagePasses, SellIn: 5, Quality: 49}},
+			expected: domain.Item{Name: gildedrose.BackstagePasses, SellIn: 4, Quality: 50},
+		},
+		{
+			name:     "BackstagePasses drop to 0 quality after concert",
+			testData: []*domain.Item{{Name: gildedrose.BackstagePasses, SellIn: 0, Quality: 20}},
+			expected: domain.Item{Name: gildedrose.BackstagePasses, SellIn: -1, Quality: 0},
+		},
+		{
+			name:     "Sulfuras never decreases in quality or SellIn, SellIn positive",
+			testData: []*domain.Item{{Name: gildedrose.Sulfuras, SellIn: 10, Quality: 80}},
+			expected: domain.Item{Name: gildedrose.Sulfuras, SellIn: 10, Quality: 80},
+		},
+		{
+			name:     "Sulfuras never decreases in quality or SellIn, SellIn negative",
+			testData: []*domain.Item{{Name: gildedrose.Sulfuras, SellIn: -1, Quality: 80}},
+			expected: domain.Item{Name: gildedrose.Sulfuras, SellIn: -1, Quality: 80},
+		},
+		{
+			name:     "Create Sulfuras item with quality different than 80",
+			testData: []*domain.Item{{Name: gildedrose.Sulfuras, SellIn: 10, Quality: 1000}},
+			expected: domain.Item{Name: gildedrose.Sulfuras, SellIn: 10, Quality: 80},
+		},
+		{
+			name:     "Conjured items degrade in quality twice as fast - before sell-by date - initial quality 6",
+			testData: []*domain.Item{{Name: gildedrose.Conjured, SellIn: 3, Quality: 6}},
+			expected: domain.Item{Name: gildedrose.Conjured, SellIn: 2, Quality: 4},
+		},
+		{
+			name:     "Conjured items degrade in quality twice as fast - before sell-by date - initial quality 1",
+			testData: []*domain.Item{{Name: gildedrose.Conjured, SellIn: 3, Quality: 1}},
+			expected: domain.Item{Name: gildedrose.Conjured, SellIn: 2, Quality: 0},
+		},
+		{
+			name:     "Conjured items degrade in quality twice as fast - before sell-by date - initial quality 0",
+			testData: []*domain.Item{{Name: gildedrose.Conjured, SellIn: -3, Quality: 0}},
+			expected: domain.Item{Name: gildedrose.Conjured, SellIn: -4, Quality: 0},
+		},
+		{
+			name:     "Conjured items degrade in quality twice as fast - after sell-by date",
+			testData: []*domain.Item{{Name: gildedrose.Conjured, SellIn: 0, Quality: 6}},
+			expected: domain.Item{Name: gildedrose.Conjured, SellIn: -1, Quality: 2},
+		},
+		{
+			name:     "Create item with quality bigger than 50",
+			testData: []*domain.Item{{Name: gildedrose.Conjured, SellIn: 10, Quality: 100}},
+			expected: domain.Item{Name: gildedrose.Conjured, SellIn: 9, Quality: 0},
+		},
+		{
+			name:     "Create item with quality less than 0",
+			testData: []*domain.Item{{Name: gildedrose.Conjured, SellIn: 10, Quality: -100}},
+			expected: domain.Item{Name: gildedrose.Conjured, SellIn: 9, Quality: 0},
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			gildedrose.UpdateQuality(tc.testData)
+			require.Equal(t, tc.expected, *tc.testData[0])
+		})
 	}
 }
diff --git a/go/go.mod b/go/go.mod
index 00f9da4e..2a0cf8ea 100644
--- a/go/go.mod
+++ b/go/go.mod
@@ -1,3 +1,10 @@
 module github.com/emilybache/gildedrose-refactoring-kata
 
 go 1.18
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/stretchr/testify v1.9.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)
diff --git a/go/texttest_fixture.go b/go/texttest_fixture.go
index 5c965064..196561dd 100644
--- a/go/texttest_fixture.go
+++ b/go/texttest_fixture.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"github.com/emilybache/gildedrose-refactoring-kata/gildedrose/domain"
 	"os"
 	"strconv"
 
@@ -11,7 +12,7 @@ import (
 func main() {
 	fmt.Println("OMGHAI!")
 
-	var items = []*gildedrose.Item{
+	var items = []*domain.Item{
 		{"+5 Dexterity Vest", 10, 20},
 		{"Aged Brie", 2, 0},
 		{"Elixir of the Mongoose", 5, 7},