doubly-linked-list-typed/test/index.test.ts

Doubly Linked List

import {DoublyLinkedList} from '../src';

describe('DoublyLinkedList Operation Test', () => {
    let list: DoublyLinkedList<number>;
    let objectList: DoublyLinkedList<{ keyA: number }>;

    beforeEach(() => {
        list = new DoublyLinkedList();
        objectList = new DoublyLinkedList();
    });

    it('should initialize an empty list', () => {
        expect(list.length).toBe(0);
        expect(list.head).toBeNull();
        expect(list.tail).toBeNull();
    });

    it('should push elements to the list', () => {
        list.push(1);
        list.push(2);
        list.push(3);
        expect(list.length).toBe(3);
        expect(list.head!.val).toBe(1);
        expect(list.tail!.val).toBe(3);
    });

    it('should pop elements from the end of the list', () => {
        list.push(1);
        list.push(2);
        const poppedValue = list.pop();
        expect(poppedValue).toBe(2);
        expect(list.length).toBe(1);
        expect(list.head!.val).toBe(1);
        expect(list.tail!.val).toBe(1);
    });
    it('should insert elements at specific positions', () => {
        list.push(1);
        list.push(2);
        list.push(3);

        // Inserting at the beginning
        list.insertAt(0, 0);
        expect(list.length).toBe(4);
        expect(list.getAt(0)).toBe(0);
        expect(list.getAt(1)).toBe(1);

        // Inserting in the middle
        list.insertAt(2, 1.5);
        expect(list.length).toBe(5);
        expect(list.getAt(2)).toBe(1.5);
        expect(list.getAt(3)).toBe(2);

        // Inserting at the end
        list.insertAt(5, 4);
        expect(list.length).toBe(6);
        expect(list.getAt(5)).toBe(4);
        expect(list.tail!.val).toBe(4);
    });

    it('should delete elements at specific positions', () => {
        list.push(1);
        list.push(2);
        list.push(3);

        // Deleting from the beginning
        const deletedValue = list.deleteAt(0);
        expect(deletedValue).toBe(1);
        expect(list.length).toBe(2);
        expect(list.head!.val).toBe(2);

        // Deleting from the middle
        list.deleteAt(0); // Deleting the second element
        expect(list.length).toBe(1);
        expect(list.head!.val).toBe(3);

        // Deleting from the end
        list.deleteAt(0);
        expect(list.length).toBe(0);
        expect(list.head).toBeNull();
        expect(list.tail).toBeNull();
    });

    it('should delete elements by value', () => {
        list.push(1);
        list.push(2);
        list.push(3);

        list.delete(2);
        expect(list.length).toBe(2);
        expect(list.head!.val).toBe(1);
        expect(list.tail!.val).toBe(3);

        list.delete(1);
        expect(list.length).toBe(1);
        expect(list.head!.val).toBe(3);

        list.delete(3);
        expect(list.length).toBe(0);
        expect(list.head).toBeNull();
        expect(list.tail).toBeNull();
    });

    it('should reverse the linked list', () => {
        list.push(1);
        list.push(2);
        list.push(3);

        list.reverse();

        expect(list.toArray()).toEqual([3, 2, 1]);
        expect(list.toArrayReverse()).toEqual([1, 2, 3]);
    });

    it('should map elements using a callback function', () => {
        list.push(1);
        list.push(2);
        list.push(3);

        const mappedList = list.map(val => val * 2);

        expect(mappedList.toArray()).toEqual([2, 4, 6]);
    });

    it('should filter elements using a callback function', () => {
        list.push(1);
        list.push(2);
        list.push(3);
        list.push(4);

        const filteredList = list.filter(val => val % 2 === 0);

        expect(filteredList.toArray()).toEqual([2, 4]);
    });

    it('should reduce elements using a callback function and an initial value', () => {
        list.push(1);
        list.push(2);
        list.push(3);
        list.push(4);

        const sum = list.reduce((acc, val) => acc + val, 0);

        expect(sum).toBe(10);
    });

    it('should insert an element after a specific value', () => {
        list.push(1);
        list.push(2);
        list.push(3);

        list.insertAfter(2, 2.5);

        expect(list.toArray()).toEqual([1, 2, 2.5, 3]);
    });

    it('should insert an element before a specific value', () => {
        list.push(1);
        list.push(2);
        list.push(3);

        list.insertBefore(2, 1.5);

        expect(list.toArray()).toEqual([1, 1.5, 2, 3]);
    });
    it('should find the first element that satisfies a condition', () => {
        list.push(1);
        list.push(2);
        list.push(3);

        const found = list.find(val => val % 2 === 0);

        expect(found).toBe(2);
    });

    it('should find the index of an element', () => {
        list.push(1);
        list.push(2);
        list.push(3);

        const index = list.indexOf(2);

        expect(index).toBe(1);
    });

    it('should find the last element that satisfies a condition', () => {
        list.push(1);
        list.push(2);
        list.push(3);
        list.push(4);

        const lastEven = list.findLast(val => val % 2 === 0);

        expect(lastEven).toBe(4);
    });

    it('should clear the linked list', () => {
        list.push(1);
        list.push(2);
        list.push(3);

        list.clear();

        expect(list.length).toBe(0);
        expect(list.head).toBe(null);
        expect(list.tail).toBe(null);
    });

    it('should create a reversed array of values', () => {
        list.push(1);
        list.push(2);
        list.push(3);

        const reversedArray = list.toArrayReverse();

        expect(reversedArray).toEqual([3, 2, 1]);
    });

    it('should reverse the linked list', () => {
        list.push(1);
        list.push(2);
        list.push(3);

        list.reverse();

        expect(list.toArray()).toEqual([3, 2, 1]);
        expect(list.head?.val).toBe(3);
        expect(list.tail?.val).toBe(1);
    });

    it('should iterate over each element and apply a callback', () => {
        list.push(1);
        list.push(2);
        list.push(3);

        const result: number[] = [];
        list.forEach(val => {
            result.push(val * 2);
        });

        expect(result).toEqual([2, 4, 6]);
    });

    it('should create a new linked list by applying a mapping function', () => {
        list.push(1);
        list.push(2);
        list.push(3);

        const mappedList = list.map(val => val * 2);

        expect(mappedList.toArray()).toEqual([2, 4, 6]);
    });

    it('should create a new linked list by filtering elements', () => {
        list.push(1);
        list.push(2);
        list.push(3);
        list.push(4);

        const filteredList = list.filter(val => val % 2 === 0);

        expect(filteredList.toArray()).toEqual([2, 4]);
    });

    it('should reduce the linked list to a single value', () => {
        list.push(1);
        list.push(2);
        list.push(3);

        const sum = list.reduce((acc, val) => acc + val, 0);

        expect(sum).toBe(6);
    });

    it('should insert a new value after an existing value', () => {
        list.push(1);
        list.push(2);
        list.push(3);

        const success = list.insertAfter(2, 4);
        expect(success).toBe(true);
        expect(list.toArray()).toEqual([1, 2, 4, 3]);
    });

    it('should insert a new value before an existing value', () => {
        list.push(1);
        list.push(2);
        list.push(3);

        const success = list.insertBefore(2, 0);
        expect(success).toBe(true);
        expect(list.toArray()).toEqual([1, 0, 2, 3]);
    });

    it('should not insert a new value after a non-existing value', () => {
        list.push(1);
        list.push(2);
        list.push(3);

        const success = list.insertAfter(4, 5);
        expect(success).toBe(false);
        expect(list.toArray()).toEqual([1, 2, 3]);
    });

    it('should not insert a new value before a non-existing value', () => {
        list.push(1);
        list.push(2);
        list.push(3);

        const success = list.insertBefore(4, 0);
        expect(success).toBe(false);
        expect(list.toArray()).toEqual([1, 2, 3]);
    });

    it('should insert and manipulate objects with numeric properties', () => {
        const obj1 = {keyA: 10};
        const obj2 = {keyA: 20};
        const obj3 = {keyA: 30};

        objectList.push(obj1);
        objectList.push(obj2);
        objectList.push(obj3);

        expect(objectList.toArray()).toEqual([obj1, obj2, obj3]);

        const newObj = {keyA: 25}; // Corrected newObj value
        const insertSuccess = objectList.insertBefore(obj2, newObj);
        expect(insertSuccess).toBe(true);

        const findNode = objectList.findNode(newObj); // Use newObj instead of obj2
        expect(findNode?.val).toEqual(newObj);

        const deleted = objectList.delete(newObj); // Use newObj instead of obj2
        expect(deleted).toBe(true);

        const poppedObj = objectList.pop();
        expect(poppedObj).toBe(obj3);

        const shiftedObj = objectList.shift();
        expect(shiftedObj).toBe(obj1);
    });
});