Effector

Effector is a small JavaScript library for testing asynchronous functions. It was inspired by Redux-Saga and its effects model. In the project I was working on, a saga was overkill for what should have been a simple async function. I also thought testing the generator function was not as intuitive as it should be. Effector tries to make testing asynchronous functions simple and understandable.

Installing

Install Effector into your project with your favorite javascript package manager:

npm install --save-dev effector

Usage

In the function you want to test, wrap your asynchronous calls with Effector's call method. Let's say we've got an api for ordering food. A method that looks like this:

import {fetchMenu, orderFood} from 'restaurant'

async function quicklyOrder () {
  const menu = await fetchMenu()
  const deliveryTime = await orderFood(menu[0])
  return deliveryTime
}

would look like this using Effector's call method:

import {fetchMenu, orderFood} from 'restaurant'
import {call} from 'effector'

async function quicklyOrder () {
  const menu = await call(fetchMenu)
  const deliveryTime = await call(orderFood, menu[0])
  return deliveryTime
}

Doing this allows you to easily test the quicklyOrder method in a testing framework like Jest:

import {fetchMenu, orderFood} from 'restaurant'
import {quicklyOrder} from 'my-food-app'
import {mockCall, useMockCalls, resetMockCalls} from 'effector/lib/test'

// Setup mock calling
useMockCalls()

// make sure to clean up mock calls after every test
afterEach(() => {
  resetMockCalls()
})

it('orders the first thing on the menu', async () => {
  mockCall(fetchMenu, ['chicken', 'beef', 'pork'])
  const mockOrderFood = mockCall(orderFood, jest.fn(() => '30 minutes')
  const deliveryTime = await quicklyOrder()
  expect(mockOrderFood).toHaveBeenCalledWith('chicken')
  expect(deliveryTime).toBe('30 minutes')
})

jwillesen/effector

Effector

Installing

Usage