test-flat

A test framework extension to support resources teardown and cleanup in flat tests.

Motivation

Writing flat (shallow) test suites has a number of advantages. However, testing frameworks rarely support before/after hooks as a part of an individual test. Such support would allow to create and clean up resources necessary for a single test suite, without having to rely on beforeEach/afterEach global hooks.

Getting started

Install

$ npm install test-flat --save-dev

Extend Jest

// jest.setup.js
import 'test-flat'

Example

Here's an example of a flat test suite that tears down a Puppeteer browser and cleans up afterwards as a part of a single test suite:

import * as puppeteer from 'puppeteer'

test.flat(
  'renders the header element on the homepage',
  (context) => {
    await context.page.goto('https://github.com')
    const headerElement = await context.page.evaluate(() => {
      return document.getElementById('header')
    })

    expect(headerElement).toBeTruthy()
  },
  async () => {
    // Create a browser and a new page
    // before the test suite.
    const browser = await puppeteer.launch()
    const page = await browser.newPage()
    return {
      browser
      page,
    }
  },
  async (context) => {
    // Await until the browser is closed
    // before finishing the test.
    return context.browser.close()
  }
)

Both test.only.flat and test.skip.flat are supported.

API

function flatTest<Context>(
  title: string,
  suite: (context: Context) => Promise<any>,
  before?: () => Promise<Context>,
  after?: (context: Context) => Promise<any>
): void

title

A test suite title.

suite

A test suite itself.

Test suite function in test-flat is always an asynchronous function and does not support the done callback argument.

before

An optional teardown hook to create any resources necessary for the respective test. Anything returned from this hook will be available as the context argument in the suite and after functions.

after

An optional cleanup hook executed after the test is finished (passed or failed). Accepts an optional context argument to clean up the resources created as a part of the before hook.