Add jest tests.

.babelrc

@@ -1,11 +1,3 @@
 {
-  "presets": [
-    [
-      "env", {
-        "targets": {
-          "node": "current"
-        }
-      }
-    ]
-  ]
+  "presets": ["env"]
 }

.eslintrc

@@ -0,0 +1,8 @@
+{
+  "root": true,
+  "extends": "airbnb",
+  "plugins": ["jest"],
+  "env": {
+    "jest/globals": true
+  }
+}

.gitignore

@@ -1,3 +1,2 @@
 node_modules
-build
 .idea

package.json

@@ -4,8 +4,8 @@
   "description": "Data structures on JavaScript",
   "main": "index.js",
   "scripts": {
-    "build": "babel src -d build",
-    "babel-node": "babel-node"
+    "lint": "eslint ./src/*",
+    "test": "jest"
   },
   "repository": {
     "type": "git",
@@ -19,7 +19,15 @@
   },
   "homepage": "https://github.com/trekhleb/data-structures#readme",
   "devDependencies": {
+    "@types/jest": "^22.2.2",
     "babel-cli": "^6.26.0",
-    "babel-preset-env": "^1.6.1"
+    "babel-preset-env": "^1.6.1",
+    "eslint": "^4.19.1",
+    "eslint-config-airbnb": "^16.1.0",
+    "eslint-plugin-import": "^2.9.0",
+    "eslint-plugin-jest": "^21.15.0",
+    "eslint-plugin-jsx-a11y": "^6.0.3",
+    "eslint-plugin-react": "^7.7.0",
+    "jest": "^22.4.3"
   }
 }

src/data-structures/linked-list/LinkedList.js

@@ -1,6 +1,6 @@
-import { Node } from './Node';
+import Node from './Node';
 
-export class LinkedList {
+export default class LinkedList {
   constructor() {
     this.head = null;
   }
@@ -17,12 +17,12 @@ export class LinkedList {
 
     // Rewind to last node.
     let currentNode = this.head;
-    while (currentNode.nextNode !== null) {
-      currentNode = currentNode.nextNode;
+    while (currentNode.next !== null) {
+      currentNode = currentNode.next;
     }
 
     // Attach new node to the end of linked list.
-    currentNode.nextNode = newNode;
+    currentNode.next = newNode;
 
     return newNode;
   }
@@ -31,21 +31,19 @@ export class LinkedList {
     this.head = new Node(value, this.head);
   }
 
-  deleteWithValue(value) {
-
-  }
-
-  render() {
+  toArray() {
+    const listArray = [];
     let currentNode = this.head;
-    let index = 0;
 
-    while(currentNode.nextNode !== null) {
-      console.log(`Node #${index} data: ${currentNode.value}`);
-      currentNode = currentNode.nextNode;
-      index++;
+    while (currentNode) {
+      listArray.push(currentNode.value);
+      currentNode = currentNode.next;
     }
 
-    // Print the tail.
-    console.log(`Node #${index} data: ${currentNode.value}`);
+    return listArray;
+  }
+
+  toString() {
+    return this.toArray().toString();
   }
 }

src/data-structures/linked-list/Node.js

@@ -0,0 +1,6 @@
+export default class Node {
+  constructor(value, next = null) {
+    this.value = value;
+    this.next = next;
+  }
+}

src/data-structures/linked-list/__test__/LinkedList.test.js

@@ -0,0 +1,23 @@
+import LinkedList from '../LinkedList';
+
+describe('LinkedList', () => {
+  it('should create empty linked list', () => {
+    const linkedList = new LinkedList();
+    expect(linkedList).toBeDefined();
+  });
+
+  it('should append node to linked list', () => {
+    const linkedList = new LinkedList();
+    linkedList.append(1);
+    linkedList.append(2);
+    expect(linkedList.toString()).toBe('1,2');
+  });
+
+  it('should prepend node to linked list', () => {
+    const linkedList = new LinkedList();
+    linkedList.append(1);
+    linkedList.append(2);
+    linkedList.prepend(3);
+    expect(linkedList.toString()).toBe('3,1,2');
+  });
+});

src/data-structures/linked-list/__test__/Node.test.js

@@ -0,0 +1,9 @@
+import Node from '../Node';
+
+describe('Node', () => {
+  it('should create list node with value', () => {
+    const node = new Node(1);
+    expect(node.value).toBe(1);
+    expect(node.next).toBeNull();
+  });
+});

src/data_structures/linked_list/Node.js

@@ -1,6 +0,0 @@
-export class Node {
-  constructor(value, nextNode = null) {
-    this.value = value;
-    this.nextNode = nextNode;
-  }
-}

src/data_structures/linked_list/index.js

@@ -1,11 +0,0 @@
-import { LinkedList } from "./LinkedList";
-
-const linkedList = new LinkedList();
-
-linkedList.append(1);
-linkedList.append(2);
-linkedList.append(3);
-linkedList.prepend(4);
-linkedList.prepend(5);
-
-linkedList.render();