MinHeapAdhoc.test.js

import MinHeapAdhoc from '../MinHeapAdhoc';

describe('MinHeapAdhoc', () => {
  it('should create an empty min heap', () => {
    const minHeap = new MinHeapAdhoc();

    expect(minHeap).toBeDefined();
    expect(minHeap.peek()).toBe(undefined);
    expect(minHeap.isEmpty()).toBe(true);
  });

  it('should add items to the heap and heapify it up', () => {
    const minHeap = new MinHeapAdhoc();

    minHeap.add(5);
    expect(minHeap.isEmpty()).toBe(false);
    expect(minHeap.peek()).toBe(5);
    expect(minHeap.toString()).toBe('5');

    minHeap.add(3);
    expect(minHeap.peek()).toBe(3);
    expect(minHeap.toString()).toBe('3,5');

    minHeap.add(10);
    expect(minHeap.peek()).toBe(3);
    expect(minHeap.toString()).toBe('3,5,10');

    minHeap.add(1);
    expect(minHeap.peek()).toBe(1);
    expect(minHeap.toString()).toBe('1,3,10,5');

    minHeap.add(1);
    expect(minHeap.peek()).toBe(1);
    expect(minHeap.toString()).toBe('1,1,10,5,3');

    expect(minHeap.poll()).toBe(1);
    expect(minHeap.toString()).toBe('1,3,10,5');

    expect(minHeap.poll()).toBe(1);
    expect(minHeap.toString()).toBe('3,5,10');

    expect(minHeap.poll()).toBe(3);
    expect(minHeap.toString()).toBe('5,10');
  });

  it('should poll items from the heap and heapify it down', () => {
    const minHeap = new MinHeapAdhoc();

    minHeap.add(5);
    minHeap.add(3);
    minHeap.add(10);
    minHeap.add(11);
    minHeap.add(1);

    expect(minHeap.toString()).toBe('1,3,10,11,5');

    expect(minHeap.poll()).toBe(1);
    expect(minHeap.toString()).toBe('3,5,10,11');

    expect(minHeap.poll()).toBe(3);
    expect(minHeap.toString()).toBe('5,11,10');

    expect(minHeap.poll()).toBe(5);
    expect(minHeap.toString()).toBe('10,11');

    expect(minHeap.poll()).toBe(10);
    expect(minHeap.toString()).toBe('11');

    expect(minHeap.poll()).toBe(11);
    expect(minHeap.toString()).toBe('');

    expect(minHeap.poll()).toBe(undefined);
    expect(minHeap.toString()).toBe('');
  });

  it('should heapify down through the right branch as well', () => {
    const minHeap = new MinHeapAdhoc();

    minHeap.add(3);
    minHeap.add(12);
    minHeap.add(10);

    expect(minHeap.toString()).toBe('3,12,10');

    minHeap.add(11);
    expect(minHeap.toString()).toBe('3,11,10,12');

    expect(minHeap.poll()).toBe(3);
    expect(minHeap.toString()).toBe('10,11,12');
  });
});