From f8bd4fd8fa6c8dcb0d26f54a6ed7d80e5443d65b Mon Sep 17 00:00:00 2001
From: Adrian Mejia <me@adrianmejia.com>
Date: Fri, 19 Apr 2019 12:27:58 -0400
Subject: [PATCH] fix(linked-list): insert in the middle bug

When inserting an item on the middle of a linked list one reference was not being updated properly.

Fixed #8
---
 src/data-structures/linked-lists/linked-list.js      | 2 +-
 src/data-structures/linked-lists/linked-list.spec.js | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/data-structures/linked-lists/linked-list.js b/src/data-structures/linked-lists/linked-list.js
index b9440791..13670de7 100644
--- a/src/data-structures/linked-lists/linked-list.js
+++ b/src/data-structures/linked-lists/linked-list.js
@@ -96,7 +96,7 @@ class LinkedList {
       newNode.next = current; // <5>
 
       current.previous.next = newNode; // <6>
-      if (current.next) { current.next.previous = newNode; } // <7>
+      current.previous = newNode; // <7>
       this.size += 1;
       return newNode;
     }
diff --git a/src/data-structures/linked-lists/linked-list.spec.js b/src/data-structures/linked-lists/linked-list.spec.js
index e7b438b5..85345fc9 100644
--- a/src/data-structures/linked-lists/linked-list.spec.js
+++ b/src/data-structures/linked-lists/linked-list.spec.js
@@ -165,8 +165,12 @@ describe('LinkedList Test', () => {
       it('should insert at the middle', () => {
         const newNode = linkedList.add('middle', 1);
         expect(newNode.value).toBe('middle');
+        // checking the 4 surrounding links were updated
         expect(newNode.next.value).toBe('found');
         expect(newNode.previous.value).toBe(0);
+        expect(linkedList.get(0).next.value).toBe('middle');
+        expect(linkedList.get(2).previous.value).toBe('middle');
+
         expect(linkedList.size).toBe(3);
         expect(linkedList.first.value).toBe(0);
       });