couchpotato-linked-list/dist/ds/list/linked-list.test.js

DoublyLinkedList implementation in javascript

"use strict";

var _linkedList = require("./linked-list");

describe('Item is the basic node for a linked list', function () {
  test('node can be created with a value, or with both value and next node', function () {
    var n = new _linkedList.Item(10);
    expect(n.getValue()).toBe(10);
  });
  test('node can be created with a value, or with both value and next node', function () {
    var n = new _linkedList.Item(10);
    var nn = new _linkedList.Item(20, n);
    expect(nn.getValue()).toBe(20);
    expect(nn.getNext()).toBe(n);
  });
});
describe('LinkedList using Item', function () {
  test('Empty Linked list with head and tail pointing to null', function () {
    var ll = new _linkedList.LinkedList();
    expect(ll.head()).toBe(null);
    expect(ll.tail()).toBe(null);
    expect(ll.length()).toBe(0);
  });
  test('Linked list - prepend an element', function () {
    var ll = new _linkedList.LinkedList();
    ll.prepend(1);
    expect(ll.head().getValue()).toBe(1);
    expect(ll.tail().getValue()).toBe(1);
    expect(ll.length()).toBe(1);
    ll.prepend(2);
    expect(ll.head().getValue()).toBe(2);
    expect(ll.tail().getValue()).toBe(1);
    expect(ll.length()).toBe(2);
    ll.prepend(3);
    var first = ll.head();
    var second = first.getNext();
    var third = second.getNext();
    expect(first.getValue()).toBe(3);
    expect(second.getValue()).toBe(2);
    expect(third.getValue()).toBe(1);
    expect(second.getPrev().getValue()).toBe(3);
  });
  test('Linked list - append an element', function () {
    var ll = new _linkedList.LinkedList();
    ll.append(1);
    expect(ll.head().getValue()).toBe(1);
    expect(ll.tail().getValue()).toBe(1);
    expect(ll.length()).toBe(1);
    ll.append(2);
    expect(ll.head().getValue()).toBe(1);
    expect(ll.tail().getValue()).toBe(2);
    expect(ll.length()).toBe(2);
    var first = ll.head();
    var second = ll.tail();
    expect(first.getNext()).toBe(second);
    expect(second.getPrev()).toBe(first);
    expect(first.getPrev()).toBe(null);
    expect(second.getNext()).toBe(null);
  });
  test('Linked list - remove from first', function () {
    var ll = new _linkedList.LinkedList();
    expect(ll.removeFromFront()).toBe(undefined);
    ll.append(1);
    var fn = ll.removeFromFront();
    expect(fn.getValue()).toBe(1);
    expect(fn.getNext()).toBe(null);
    expect(fn.getPrev()).toBe(null);
    expect(ll.head()).toBe(null);
    expect(ll.tail()).toBe(null);
    expect(ll.length()).toBe(0);
    ll.append(1);
    ll.append(2);
    ll.append(3);
    var fn1 = ll.removeFromFront();
    expect(fn1.getValue()).toBe(1);
    expect(fn1.getNext()).toBe(null);
    expect(fn1.getPrev()).toBe(null);
    expect(ll.head().getValue()).toBe(2);
    expect(ll.length()).toBe(2);
    expect(ll.head().getPrev()).toBe(null);
  });
  test('Linked list - remove from last', function () {
    var ll = new _linkedList.LinkedList();
    expect(ll.removeFromEnd()).toBe(undefined);
    ll.append(1);
    var last = ll.removeFromEnd();
    expect(last.getValue()).toBe(1);
    expect(last.getNext()).toBe(null);
    expect(last.getPrev()).toBe(null);
    expect(ll.head()).toBe(null);
    expect(ll.tail()).toBe(null);
    expect(ll.length()).toBe(0);
    ll.append(1);
    ll.append(2);
    ll.append(3);
    var last1 = ll.removeFromEnd();
    expect(last1.getValue()).toBe(3);
    expect(last1.getNext()).toBe(null);
    expect(last1.getPrev()).toBe(null);
    expect(ll.head().getValue()).toBe(1);
    expect(ll.tail().getValue()).toBe(2);
    expect(ll.length()).toBe(2);
    expect(ll.tail().getNext()).toBe(null);
  });
  test('Linked list - get a node from a given index', function () {
    var ll = new _linkedList.LinkedList();
    ll.append(1);
    ll.append(2);
    ll.append(3);
    ll.append(4);
    ll.append(5);
    ll.append(6);
    expect(ll.get(0)).toBe(1);
    expect(ll.get(2)).toBe(3);
    expect(ll.get(ll.length() - 1)).toBe(6);
    expect(ll.get(ll.length())).toBe(undefined);
    expect(ll.get(-1)).toBe(undefined);
  });
  test('Linked list - remove a given node', function () {
    var ll = new _linkedList.LinkedList();
    ll.append(0);
    expect(ll.removeAt(0)).toBe(0);
  });
});