import { describe, it, test, expect, jest, afterEach, beforeEach } from '@jest/globals'
import { add } from '@sanjo/mathematics'
import { createCachingFunction } from './createCachingFunction.js'
import { identity } from '@sanjo/identity'

describe('createCachingFunction', () => {
  it('caches the result', () => {
    const cachingAdd = createCachingFunction(add)
    jest.spyOn(cachingAdd.cache, 'set')
    const result = cachingAdd(1, 2)
    expect(cachingAdd.cache.set).toHaveBeenCalledWith([1, 2], result)
  })

  describe('when the result is cached', () => {
    it('returns the cached result', () => {
      const cachingFn = createCachingFunction(identity)
      const argument = 1
      const mockedResult = {}
      cachingFn.cache.set([argument], mockedResult)
      jest.spyOn(cachingFn.cache, 'retrieve')
      const result = cachingFn(argument)
      expect(cachingFn.cache.retrieve).toHaveBeenCalledWith([argument])
      expect(result).toBe(mockedResult)
    })
  })
})