JavaScript/Data-Structures/Heap/test/MinPriorityQueue.test.js

import { MinPriorityQueue } from '../MinPriorityQueue'

describe('MinPriorityQueue', () => {
  const values = [5, 2, 4, 1, 7, 6, 3, 8]
  const capacity = values.length
  let queue

  beforeEach(() => {
    queue = new MinPriorityQueue(capacity)
    values.forEach(v => queue.insert(v))
  })

  it('Check heap ordering', () => {
    const mockFn = jest.fn()
    queue.print(mockFn)

    expect(mockFn.mock.calls.length).toBe(1) // Expect one call
    expect(mockFn.mock.calls[0].length).toBe(1) // Expect one argument

    const heap = mockFn.mock.calls[0][0]
    expect(heap.length).toBe(capacity)
    expect(heap).toStrictEqual([1, 2, 3, 5, 7, 6, 4, 8])
  })

  it('heapSort() expected to reverse the heap ordering', () => {
    queue.heapReverse()
    const mockFn = jest.fn()
    queue.print(mockFn)

    expect(mockFn.mock.calls.length).toBe(1)
    expect(mockFn.mock.calls[0].length).toBe(1)

    const heap = mockFn.mock.calls[0][0]
    expect(heap.length).toBe(capacity)
    expect(heap).toStrictEqual([8, 7, 6, 5, 4, 3, 2, 1])
  })

  describe('delete() function work properly', () => {
    it('return undefined if heap is empty', () => {
      const minqueue = new MinPriorityQueue(capacity)
      const min = minqueue.delete()
      expect(min).toBe(undefined)
    })
    it('return min value and remove it', () => {
      const sortedValues = values.sort()
      let initialSize = queue.size
      sortedValues.forEach((minValue, index) => {
        const min = queue.delete()
        expect(min).toBe(minValue)
        expect(queue.size).toBe(--initialSize)
      })
      expect(queue.size).toBe(0)
    })
  })
})