diff --git a/DoublyLinkedList/DoublyLinkedList.go b/DoublyLinkedList/DoublyLinkedList.go
index e6e39f9..5310ae2 100644
--- a/DoublyLinkedList/DoublyLinkedList.go
+++ b/DoublyLinkedList/DoublyLinkedList.go
@@ -18,20 +18,23 @@ func (list *LinkedList) InsertFirst(i int) {
 		data.next = list.head
 	}
 	list.head = data
+
+	if list.tail == nil{
+		list.tail = data
+	}
 }
 
 func (list *LinkedList) InsertLast(i int) {
 	data := &Node{data: i}
-	if list.head == nil {
-		list.head = data
-		list.tail = data
-		return
-	}
 	if list.tail != nil {
 		list.tail.next = data
 		data.prev = list.tail
 	}
 	list.tail = data
+
+	if list.head == nil {
+		list.head = data
+	}
 }
 
 func (list *LinkedList) RemoveByValue(i int) bool {
@@ -40,7 +43,11 @@ func (list *LinkedList) RemoveByValue(i int) bool {
 	}
 	if list.head.data == i {
 		list.head = list.head.next
-		list.head.prev = nil
+		if list.head != nil {
+			list.head.prev = nil
+		} else {
+			list.tail = nil
+		}
 		return true
 	}
 	if list.tail.data == i {
diff --git a/DoublyLinkedList/DoublyLinkedList_test.go b/DoublyLinkedList/DoublyLinkedList_test.go
new file mode 100644
index 0000000..24bcc38
--- /dev/null
+++ b/DoublyLinkedList/DoublyLinkedList_test.go
@@ -0,0 +1,221 @@
+package DoublyLinkedList
+
+import "testing"
+
+func TestLinkedList_InsertFirst(t *testing.T) {
+	ll := LinkedList{}
+
+	var f, l int
+
+	for i := 1; i <= 1000; i++ {
+		ll.InsertFirst(i)
+		if f, _ = ll.GetFirst(); f != i {
+			t.Fatalf("GetFirst Error want:%d but return:%d", i, f)
+		}
+		if l, _ = ll.GetLast(); l != 1 {
+			t.Fatalf("GetFirst Error want:%d but return:%d", 1, l)
+		}
+	}
+
+	if ll.GetSize() != 1000{
+		t.Fatal()
+	}
+}
+
+func TestLinkedList_InsertLast(t *testing.T) {
+	ll := LinkedList{}
+
+	var f, l int
+
+	for i := 1; i <= 1000; i++ {
+		ll.InsertLast(i)
+		if f, _ = ll.GetLast(); f != i {
+			t.Fatalf("GetFirst Error want:%d but return:%d", i, f)
+		}
+		if l, _ = ll.GetFirst(); l != 1 {
+			t.Fatalf("GetFirst Error want:%d but return:%d", 1, l)
+		}
+	}
+
+	if ll.GetSize() != 1000{
+		t.Fatal()
+	}
+}
+
+func TestLinkedList_GetSize(t *testing.T) {
+	ll := LinkedList{}
+	count := 1000
+	for i := 1; i <= count; i++ {
+		ll.InsertFirst(i)
+		if ll.GetSize() != i {
+			t.Fatal()
+		}
+	}
+}
+
+func TestLinkedList_GetSize2(t *testing.T) {
+	ll := LinkedList{}
+	count := 1000
+	for i := 1; i <= count; i++ {
+		ll.InsertLast(i)
+		if ll.GetSize() != i {
+			t.Fatal()
+		}
+	}
+}
+
+func TestLinkedList_GetFirst(t *testing.T) {
+	ll := LinkedList{}
+	count := 1000
+	for i := 1; i <= count; i++ {
+		ll.InsertFirst(i)
+	}
+
+	if v, _ := ll.GetFirst(); v != count {
+		t.Fatal()
+	}
+}
+
+func TestLinkedList_GetLast(t *testing.T) {
+	ll := LinkedList{}
+	count := 1000
+	for i := 1; i <= count; i++ {
+		ll.InsertLast(i)
+	}
+
+	if v, _ := ll.GetLast(); v != count {
+		t.Fatal()
+	}
+}
+
+func TestLinkedList_GetItemsFromStart(t *testing.T) {
+	ll := LinkedList{}
+	count := 1000
+	for i := 1; i <= count; i++ {
+		ll.InsertFirst(i)
+	}
+
+	//from 1000 to 1
+	for _, v := range ll.GetItemsFromStart() {
+		if v != count {
+			t.Fatal()
+		}
+		count--
+	}
+}
+
+func TestLinkedList_GetItemsFromEnd(t *testing.T) {
+	ll := LinkedList{}
+	count := 1000
+	for i := 1; i <= count; i++ {
+		ll.InsertFirst(i)
+	}
+
+	//from 1 to 1000
+	index := 1
+	for _, v := range ll.GetItemsFromEnd() {
+		if v != index {
+			t.Fatal()
+		}
+		index++
+	}
+}
+
+func TestLinkedList_SearchValue(t *testing.T) {
+	ll := LinkedList{}
+	count := 1000
+	for i := 1; i <= count; i++ {
+		ll.InsertFirst(i)
+	}
+
+	for i := 1; i <= count; i++ {
+		if !ll.SearchValue(i) {
+			t.Fatal()
+		}
+	}
+
+	if ll.SearchValue(1001) {
+		t.Fatal()
+	}
+	if ll.SearchValue(0) {
+		t.Fatal()
+	}
+}
+
+func TestLinkedList_RemoveByValue(t *testing.T) {
+	ll := LinkedList{}
+	count := 1000
+	for i := 1; i <= count; i++ {
+		ll.InsertFirst(i)
+	}
+
+	for i := 1; i <= count; i++ {
+		ll.RemoveByValue(i)
+		if ll.SearchValue(i) {
+			t.Fatal()
+		}
+	}
+
+	if ll.GetSize() > 0 {
+		t.Fatal()
+	}
+}
+
+func TestLinkedList_RemoveByValue1(t *testing.T) {
+	ll := LinkedList{}
+	count := 1000
+	for i := 1; i <= count; i++ {
+		ll.InsertLast(i)
+	}
+
+	for i := 1; i <= count; i++ {
+		ll.RemoveByValue(i)
+		if ll.SearchValue(i) {
+			t.Fatal()
+		}
+	}
+
+	if ll.GetSize() > 0 {
+		t.Fatal()
+	}
+}
+
+func TestLinkedList_RemoveByIndex(t *testing.T) {
+	ll := LinkedList{}
+	count := 1000
+	for i := 1; i <= count; i++ {
+		ll.InsertLast(i)
+	}
+
+	//from 1 to 1000
+	for i := 1; i <= count; i++ {
+		ll.RemoveByIndex(0)
+		if ll.SearchValue(i) {
+			t.Fatal()
+		}
+	}
+
+	if ll.GetSize() > 0 {
+		t.Fatal()
+	}
+}
+
+func TestLinkedList_RemoveByIndex2(t *testing.T) {
+	ll := LinkedList{}
+	count := 1000
+	for i := 1; i <= count; i++ {
+		ll.InsertFirst(i)
+	}
+
+	//from 1 to 1000
+	for i := 1; i <= count; i++ {
+		ll.RemoveByIndex(ll.GetSize() - 1)
+		if ll.SearchValue(i) {
+			t.Fatal()
+		}
+	}
+
+	if ll.GetSize() > 0 {
+		t.Fatal()
+	}
+}