dist-javascript-algorithms-and-data-structures/dist/data-structures/linked-list/__test__/LinkedList.test.js

Algorithms and data-structures implemented on JavaScript

"use strict";

var _LinkedList = _interopRequireDefault(require("../LinkedList"));

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

describe('LinkedList', () => {
  it('should create empty linked list', () => {
    const linkedList = new _LinkedList.default();
    expect(linkedList.toString()).toBe('');
  });
  it('should append node to linked list', () => {
    const linkedList = new _LinkedList.default();
    expect(linkedList.head).toBeNull();
    expect(linkedList.tail).toBeNull();
    linkedList.append(1);
    linkedList.append(2);
    expect(linkedList.toString()).toBe('1,2');
    expect(linkedList.tail.next).toBeNull();
  });
  it('should prepend node to linked list', () => {
    const linkedList = new _LinkedList.default();
    linkedList.prepend(2);
    expect(linkedList.head.toString()).toBe('2');
    expect(linkedList.tail.toString()).toBe('2');
    linkedList.append(1);
    linkedList.prepend(3);
    expect(linkedList.toString()).toBe('3,2,1');
  });
  it('should delete node by value from linked list', () => {
    const linkedList = new _LinkedList.default();
    expect(linkedList.delete(5)).toBeNull();
    linkedList.append(1);
    linkedList.append(1);
    linkedList.append(2);
    linkedList.append(3);
    linkedList.append(3);
    linkedList.append(3);
    linkedList.append(4);
    linkedList.append(5);
    expect(linkedList.head.toString()).toBe('1');
    expect(linkedList.tail.toString()).toBe('5');
    const deletedNode = linkedList.delete(3);
    expect(deletedNode.value).toBe(3);
    expect(linkedList.toString()).toBe('1,1,2,4,5');
    linkedList.delete(3);
    expect(linkedList.toString()).toBe('1,1,2,4,5');
    linkedList.delete(1);
    expect(linkedList.toString()).toBe('2,4,5');
    expect(linkedList.head.toString()).toBe('2');
    expect(linkedList.tail.toString()).toBe('5');
    linkedList.delete(5);
    expect(linkedList.toString()).toBe('2,4');
    expect(linkedList.head.toString()).toBe('2');
    expect(linkedList.tail.toString()).toBe('4');
    linkedList.delete(4);
    expect(linkedList.toString()).toBe('2');
    expect(linkedList.head.toString()).toBe('2');
    expect(linkedList.tail.toString()).toBe('2');
    linkedList.delete(2);
    expect(linkedList.toString()).toBe('');
  });
  it('should delete linked list tail', () => {
    const linkedList = new _LinkedList.default();
    linkedList.append(1);
    linkedList.append(2);
    linkedList.append(3);
    expect(linkedList.head.toString()).toBe('1');
    expect(linkedList.tail.toString()).toBe('3');
    const deletedNode1 = linkedList.deleteTail();
    expect(deletedNode1.value).toBe(3);
    expect(linkedList.toString()).toBe('1,2');
    expect(linkedList.head.toString()).toBe('1');
    expect(linkedList.tail.toString()).toBe('2');
    const deletedNode2 = linkedList.deleteTail();
    expect(deletedNode2.value).toBe(2);
    expect(linkedList.toString()).toBe('1');
    expect(linkedList.head.toString()).toBe('1');
    expect(linkedList.tail.toString()).toBe('1');
    const deletedNode3 = linkedList.deleteTail();
    expect(deletedNode3.value).toBe(1);
    expect(linkedList.toString()).toBe('');
    expect(linkedList.head).toBeNull();
    expect(linkedList.tail).toBeNull();
  });
  it('should delete linked list head', () => {
    const linkedList = new _LinkedList.default();
    expect(linkedList.deleteHead()).toBeNull();
    linkedList.append(1);
    linkedList.append(2);
    expect(linkedList.head.toString()).toBe('1');
    expect(linkedList.tail.toString()).toBe('2');
    const deletedNode1 = linkedList.deleteHead();
    expect(deletedNode1.value).toBe(1);
    expect(linkedList.toString()).toBe('2');
    expect(linkedList.head.toString()).toBe('2');
    expect(linkedList.tail.toString()).toBe('2');
    const deletedNode2 = linkedList.deleteHead();
    expect(deletedNode2.value).toBe(2);
    expect(linkedList.toString()).toBe('');
    expect(linkedList.head).toBeNull();
    expect(linkedList.tail).toBeNull();
  });
  it('should be possible to store objects in the list and to print them out', () => {
    const linkedList = new _LinkedList.default();
    const nodeValue1 = {
      value: 1,
      key: 'key1'
    };
    const nodeValue2 = {
      value: 2,
      key: 'key2'
    };
    linkedList.append(nodeValue1).prepend(nodeValue2);

    const nodeStringifier = value => `${value.key}:${value.value}`;

    expect(linkedList.toString(nodeStringifier)).toBe('key2:2,key1:1');
  });
  it('should find node by value', () => {
    const linkedList = new _LinkedList.default();
    expect(linkedList.find({
      value: 5
    })).toBeNull();
    linkedList.append(1);
    expect(linkedList.find({
      value: 1
    })).toBeDefined();
    linkedList.append(2).append(3);
    const node = linkedList.find({
      value: 2
    });
    expect(node.value).toBe(2);
    expect(linkedList.find({
      value: 5
    })).toBeNull();
  });
  it('should find node by callback', () => {
    const linkedList = new _LinkedList.default();
    linkedList.append({
      value: 1,
      key: 'test1'
    }).append({
      value: 2,
      key: 'test2'
    }).append({
      value: 3,
      key: 'test3'
    });
    const node = linkedList.find({
      callback: value => value.key === 'test2'
    });
    expect(node).toBeDefined();
    expect(node.value.value).toBe(2);
    expect(node.value.key).toBe('test2');
    expect(linkedList.find({
      callback: value => value.key === 'test5'
    })).toBeNull();
  });
  it('should create linked list from array', () => {
    const linkedList = new _LinkedList.default();
    linkedList.fromArray([1, 1, 2, 3, 3, 3, 4, 5]);
    expect(linkedList.toString()).toBe('1,1,2,3,3,3,4,5');
  });
  it('should find node by means of custom compare function', () => {
    const comparatorFunction = (a, b) => {
      if (a.customValue === b.customValue) {
        return 0;
      }

      return a.customValue < b.customValue ? -1 : 1;
    };

    const linkedList = new _LinkedList.default(comparatorFunction);
    linkedList.append({
      value: 1,
      customValue: 'test1'
    }).append({
      value: 2,
      customValue: 'test2'
    }).append({
      value: 3,
      customValue: 'test3'
    });
    const node = linkedList.find({
      value: {
        value: 2,
        customValue: 'test2'
      }
    });
    expect(node).toBeDefined();
    expect(node.value.value).toBe(2);
    expect(node.value.customValue).toBe('test2');
    expect(linkedList.find({
      value: 2,
      customValue: 'test5'
    })).toBeNull();
  });
  it('should reverse linked list', () => {
    const linkedList = new _LinkedList.default(); // Add test values to linked list.

    linkedList.append(1).append(2).append(3);
    expect(linkedList.toString()).toBe('1,2,3');
    expect(linkedList.head.value).toBe(1);
    expect(linkedList.tail.value).toBe(3); // Reverse linked list.

    linkedList.reverse();
    expect(linkedList.toString()).toBe('3,2,1');
    expect(linkedList.head.value).toBe(3);
    expect(linkedList.tail.value).toBe(1); // Reverse linked list back to initial state.

    linkedList.reverse();
    expect(linkedList.toString()).toBe('1,2,3');
    expect(linkedList.head.value).toBe(1);
    expect(linkedList.tail.value).toBe(3);
  });
});