Unit test Hyperapp components using Cypress
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cypress-hyperapp-unit-test

Unit test Hyperapp components using Cypress

NPM

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TLDR

  • What is this? This package allows you to use Cypress test runner to unit test your Hyperapp components with zero effort. The component runs in the real browser with full power of Cypress E2E test runner: live GUI, powerful API, screen recording, historical DOM snapshots, CI support, cross-platform.

  • The line between unit testing a component that renders into a DOM, makes HTTP requests, uses browser API and an end-to-end test for a complete web application is becoming very blurry in my opinion. Hope this little bridge between Hyperapp and Cypress test runner proves it. See examples below - some of them are testing individual components, some full apps. But the unit and end-to-end tests look and run very much alike.

Install

Requires Node version 6 or above.

npm install --save-dev cypress-hyperapp-unit-test

also requires peer dependencies in your project

npm install cypress hyperapp

API

You can import this module from your own tests

import { mount } from 'cypress-hyperapp-unit-test'
// import or code state, action and view
beforeEach(() => {
  mount(state, actions, view)
})
// you get fresh mini-app running in each test

Use

In your Cypress spec files (the example below is from file cypress/integration/hello-world-spec.js) mount the application, just like you would "normally".

import { mount } from 'cypress-hyperapp-unit-test'
import { h } from 'hyperapp'
// view function we are testing
const view = (state, actions) => h('div', { class: 'greeting' }, 'Hello, World')
describe('Hello World', () => {
  beforeEach(() => {
    const state = {}
    const actions = {}
    // no state or actions for this simple example
    mount(state, actions, view)
  })
  it('shows greeting', () => {
    // use any Cypress command - we have
    // real Hyperapp application for testing
    cy.contains('.greeting', 'Hello, World')
  })
})

Start Cypress using $(npm bin)/cypress open and execute the spec. You have full end-to-end test run but with your component! Why waste time on unit testing inside synthetic DOM's blackbox if you could see the result, inspect the DOM, investigate how it works using time-travelling debugger?

Hello World shows greeting

Examples

Unit tests and E2E tests start looking very much alike. Compare TodoList unit test and TodoMVC end-to-end test.

Repo organization

  • src/index.js the main file implementing mount
  • components different Hyper components for testing
  • actions pure actions functions used from components and tests
  • apps one or more complete bundled applications (build them using npm run build)
  • cypress/integration example spec files showing various test situations

See video of tests running on CI on the project's Cypress Dashboard

API Extras

  • Mounted component's actions object is attached to the global Cypress.main variable. The name main was picked because that's what Hyperapp uses in its docs const main = app(state, ...)
  • The mount function adds an action _getState to the actions object, if there is not one already present. This allows you to get the current state of the component for inspection.
Cypress.main.setName('Joe')
Cypress.main
  ._getState()
  .its('name')
  .should('equal', 'Joe')
Cypress.main.setAge(37)
Cypress.main._getState().should('deep.equal', {
  name: 'Joe',
  age: 37
})

Note: the Cypress.main wraps returned Hyperapp actions with cy.then to queue the calls through the Cypress command queue. Thus the above code looks synchronous, but in reality there could be DOM updates, network calls, etc, and it still works.

Package scripts

  • npm run build bundles complete applications if you want to run tests against full applications
  • npm run cy:open starts Cypress GUI, which is great for TDD mode
  • npm run cy:run runs Cypress headlessly, testing all specs. Same command runs on CI with additional --record argument to record the run and send to the Cypress Dashboard

Similar adaptors

Small print

Author: Gleb Bahmutov <gleb.bahmutov@gmail.com> © 2017

License: MIT - do anything with the code, but don't blame me if it does not work.

Support: if you find any problems with this module, email / tweet / open issue on Github

MIT License

Copyright (c) 2017 Gleb Bahmutov <gleb.bahmutov@gmail.com>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.