moy-fp/test/Functor/Task/index.test.js

A functional programming library.

import Task from '../../../src/Functor/Task/index'

/**
 * you should not use this similar funciton to get value anywhere in your application
 * if you must need the inner value, you may need Comonad
 * here is just simple for test
 */
const inspect = x => new Promise(
  (resolve, reject) => x.fork(
    x => reject(`Task.reject(${typeof x === 'function' ? 'x => x + 1' : x})`),
    x => resolve(`Task.resolve(${typeof x === 'function' ? 'x => x + 1' : x})`),
  )
)

describe('test Task', () => {
  test('reject', () => {
    expect(
      inspect(Task(
        (reject, resolve) => reject(12)
      ))
    ).rejects.toBe('Task.reject(12)')
  })

  test('resolve', () => {
    expect(
      inspect(Task.of(12))
    ).resolves.toBe('Task.resolve(12)')
  })
})

describe('test map', () => {
  test('reject', () => {
    expect(
      inspect(Task(
        (reject, resolve) => reject(12)).map(
          x => x + 1
        )
      )
    ).rejects.toBe('Task.reject(12)')
  })

  test('resolve', () => {
    expect(
      inspect(Task.of(12).map(x => x + 1))
    ).resolves.toBe('Task.resolve(13)')
  })
})

describe('test join', () => {
  test('reject', () => {
    expect(
      inspect(Task(
        (reject, resolve) => resolve(
          Task(
            (rej, res) => rej(12)
          )
        )
      ).join())
    ).rejects.toBe('Task.reject(12)')
  })

  test('resolve', () => {
    expect(
      inspect(Task.of(Task.of(12)).join())
    ).resolves.toBe('Task.resolve(12)')
  })
})

describe('test chain', () => {
  test('reject', () => {
    expect(
      inspect(Task(
        (reject, resolve) => reject(12)
      ).chain(
        x => Task.of(x + 1)
      ))
    ).rejects.toBe('Task.reject(12)')
  })

  test('resolve', () => {
    expect(
      inspect(Task.of(12).chain(
        x => Task.of(x + 1)
      ))
    ).resolves.toBe('Task.resolve(13)')
  })
})

describe('test ap', () => {
  test('reject', () => {
    expect(
      inspect(Task(
        (reject, resolve) => reject(x => x + 1)
      ).ap(
        Task.of(12)
      ))
    ).rejects.toBe('Task.reject(x => x + 1)')
  })

  test('resolve', () => {
    expect(
      inspect(Task.of(x => x + 1).ap(
        Task.of(12)
      ))
    ).resolves.toBe('Task.resolve(13)')
  })
})

test('test Object.prototype.toString.call',() => {
  expect(
    Object.prototype.toString.call(
      Task.of(12)
    )
  ).toBe('[object Task]')
})