dferber90

Visual Regression Testing with Jest

This is a walkthrough of how to set up Visual Regression Testing with Jest for an application created with create-react-app.

The following walkthrough uses React as an example, but the approach should work for any modern frontend library! I assume it can be used with Angular, Vue, Cycle.js and more.

This gist walks you through a create-react-app application as an example of how to set up Visual Regression Testing in Jest using libraries I wrote recently which enable this: jsdom-screenshot, jest-transform-css and jest-transform-file.

Godofbrowser

// for multiple requests
let isRefreshing = false;
let failedQueue = [];

const processQueue = (error, token = null) => {
  failedQueue.forEach(prom => {
    if (error) {
      prom.reject(error);
    } else {
      prom.resolve(token);

markerikson

const createMySocketMiddleware = (url) => {
    return storeAPI => {
        let socket = createMyWebsocket(url);

        socket.on("message", (message) => {
            storeAPI.dispatch({
                type : "SOCKET_MESSAGE_RECEIVED",
                payload : message
            });
        });

fokusferit

Shallow

Real unit test (isolation, no children render)

Simple shallow

Calls:

• constructor
• render

markerikson

import React from "react";
import ReactDOM from "react-dom";

import configureStore from "./store/configureStore";


const store = configureStore();


const rootEl = document.getElementById("root");

rsms

function sleep(duration) {
  return new Promise(function(resolve, reject) {
    setTimeout(()=> { resolve(0) }, duration);
  })
}

async function delayedMessage(message, delay) {
  let remainingTime = await sleep(delay)
  console.log(message, `(remaining time: ${remainingTime})`)
}