Introduction to Modernizing an Enterprise React App

Video Course Overview - Modernizing an Enterprise React App

Get familiar with the sample React application's folder structure and current functionality.

What We'll Build In This React Course - Hardware Handler

Introduction

Module 1 Introduction

Learn about the motivation behind React Hooks, the benefits it can bring, and the rules that apply to all Hooks in a React application.

React Hooks - Understanding The Basic Rules and Benefits

The useState Hook is the most similar to traditional state in React class-based components, and we'll look at examples of how it works to keep track of state in functional components.

React's useState Hook - Track Functional Component States

useEffect is a game-changing hook: originally compared to lifecycle methods in React components, it's close but not truly a direct comparison.

How Does React's useEffect Hook Work?

While less often discussed, the useRef Hook deserves covering because a time will come when it's the right solution to reach for; here, we'll talk about how useRef's "mutable" value property can be useful.

Learning About The React useRef Hook And Mutable Values

Context is a powerful API to pass state within React applications, and with the introduction of the useContext Hook, accessing state in any component (class or functional) is possible.

A Step-by-Step Guide to Using React's useContext Hook

Custom hooks are arguably the most important addition of all the hooks released with React 16.8.0. Explore how custom hooks can dramatically simplify sharing code between components.

An Introduction To Custom Hooks In React

This lesson is a summary of the React Hooks we've covered in Module 1.0

Module 1 Summary

React Hooks

Introduction to Module 2: Upgrading React App Version

Module 2 Introduction

Before we can do anything else, we must upgrade our sample app's React version to start taking advantage of the advances.

Upgrade the React app version

Avoid one of the most common developer woes: different devs coding with different environment versions with the help of Volta and Node Engines.

Dev Teams, Lock Down Environment Versions With Volta

This lesson is a summary of module 2.0, where we upgraded our React version and locked in our project configuration.

Module 2 Summary

Upgrade the React App

Introduction to module 3: Code formatting setup

Module 3 Introduction

Code formatting, especially when it's set up, so you don't even have to think about it, is the best.

Code Formatting - An Overview Of Prettier And How To Set It Up

Make JavaScript code quality better and avoid bugs with the help of a linter and a strict set of rules.

How To Set Up ESLint For Modernizing A React App

This lesson is a summary of the automated code formatting and linting we set up with the help Prettier and ESLint in Module 3.0.

Module 3 Summary

Configure Prettier and ESLint

Introduction to Module 4: Refactoring to hooks

Module 4 Introduction

We dip our toes into converting a class component to a functional one with Hardware Handler's home page.

Refactor Home.js

We get our first real taste of adding hooks while refactoring the App component.

Refactor App.js

The checkout page uses multiple API calls to correctly display the items a product manager wants to ship to stores.

Refactor Checkout.js

Ah forms, a painful Achilles heel of most web applications (React apps included) since the beginning of time.

Refactor ProductForm.js

We saved the best (i.e. the most complicated) component for last. The product list, with its filters and products, is no match for our newly honed skills though.

Refactor ProductList.js

This lesson is a summary of Module 4.0, where we systematically refactored our app's outdated class components to now use React Hooks.

Module 4 Summary

Refactor React Classes to React Hooks

Module 5 Introduction

We'll write our first custom hook to fetch department info for our application in one centralized place.

Our First Custom Hook: useDepartments

Custom hooks are good for more than just drying up duplicated code; they also help simplify our components.

Simplify Complex Components with the useProducts Hook

Some custom hooks can help simplify code beyond the original components they touch.

The useCheckout Hook will do Double Duty in our App

This lesson is a summary of module 5.0's custom hooks we added to Hardware Handler.

Module 5 Summary

Create Custom Hooks for the App

Introduction to module 6: The useContext Hook

Module 6 Introduction

Bring the Context API into Hardware Handler to decrease our reliance on props.

Simplify React Prop Management With A Context Hook

Context doesn't necessarily need to live at the top level of a component to be useful.

Setting Up Contexts To Share Functions Within A React App

This lesson summarizes our addition of the Context API and useContext Hooks in Module 6.0.

Module 6 Summary

Incorporate the Context API

Module 7 Introduction

This library took aim at a few fundamental flaws in the traditional way of integration testing JavaScript applications and really changed the game when it comes to automated testing.

Introducing React Testing Library And Its Automation Capabilities

We've got a little setup work to do before we get to the actual business of writing our tests.

Strategies For Simplifying Integration Testing For React Apps

React Testing Library's approach to integration testing like a user would interact with the DOM works very well with React's function-based components.

How To Write Tests For React Container Components

Test Hardware Handler's custom hooks

Not all of our testing for our React app relies so heavily on RTL — some files Jest can handle on its own.

A Guide To API Service Layer Testing With The Jest Framework

This lesson is a summary of module 7.0, where we started adding unit and integration tests to our app to increase our confidence our app works as expected.

Module 7 Summary

Integration Testing with Jest and React Testing Library

Module 8 Introduction

End-to-end testing has never been the easiest thing to do, but Cypress challenges that statement in a big way.

Cypress.io And End-To-End Testing - What You Need To Know

Cypress gives us a big helping hand organizing and getting started with our own e2es.

Add Cypress To A React App For Automated End-To-End Testing

Cypress makes the process of writing e2es relatively simple with lots of built-in methods and documentation to show you the way to use it effectively.

Write And Run End-To-End Test Flows With Cypress.io

The Studio feature makes e2e test writing faster and easier than it's ever been before.

Try out Cypress Studio

This lesson is a summary of module 8.0, where we integrated Cypress into a React app and wrote automated end-to-end tests.

Module 8 Summary

End-to-End Testing with Cypress

Introduction to module 9: Design system libraries

Module 9 Introduction

Design systems provide more than just a bunch of prebuilt components for developers.

Why use a Design System?

Setting Ant Design up takes a little doing because it's so customizable.

How To Add Ant Design System To A React App

Ant Design's thorough documentation makes the process of replacing custom components less difficult than it might otherwise be.

Swap out Some Simple Components

While these components require a little more effort to get working, the improvements they provide are worth the time.

How To Add An Ant Design System Form To A React App

This lesson summarizes module 9.0, where we learned about the benefits of a design system and incorporated the popular Ant Design into our own app.

Module 9 Summary

Bonus Module: Add a Design System Library

Recapping Modernizing an Enterprise React App

Summing It All Up

In this course we'll dive into all the ways to modernize an existing React application - from tooling and linting, to testing and Hooks. React is a powerful, extremely popular JavaScript framework, but keeping applications up to date with all that it has to offer is tough - especially when dealing with the larger, enterprise-level business applications many developers are responsible for.

## Why this course

The newline Guide to Modernizing an Enterprise React application will cover everything you need to know to confidently work on a React application of any size, in any state, and leave it better than when you found it. 

While many React tutorials start with the latest version of React, or gloss over all the other things required to make sure apps vital to a company's success keep running, this course does not. In 54 lessons spanning 10 modules, it tackles head-on, the many things that must be considered when building and maintaining large, complex React apps.

## Course modules 

As you progress through this course, you'll gain a deeper understanding for how and why React Hooks came to be, the importance of various types of automated testing and project configuration, and how to leverage design systems to improve your application. You will gain a detailed understanding of how to modernize a React app in a real-world scenario, bringing it in line with today's development standards. 

![Home page of the Hardware Handler sample React application](https://d2uusema5elisf.cloudfront.net/courses/newline-guide-to-modernizing-an-enterprise-react-app/module_10/lesson_00.00/public/assets/hardware-handler-home-page.png)

### Part one: tooling and setup

The first part of this course will consist of getting familiar with our example application, and doing the behind-the-scenes work to set it up for success. 

We'll learn about why React Hooks came about and how to use them, how to upgrade an outdated React app successfully, and how to use tools like Volta, ESLint and Prettier to improve the app's code and development experience.

- Module 0: Meet Hardware Handler - our outdated, but promising React application.
- Module 1: [React Hooks](https://reactjs.org/docs/hooks-intro.html#motivation) - why they were created, the issues they solve and how the most common ones work.
- Module 2: Upgrading a React app - our app needs an upgrade to use Hooks, and we'll streamline development with [Volta](https://volta.sh/).
- Module 3: Project configuration - adding [Prettier](https://prettier.io/) and [ESLint](https://eslint.org/) to our app will dramatically improve code quality.  

### Part two: refactoring the code

With our app configured for success, we'll get down to the business of refactoring Hardware Handler. 

I'll show you my strategy for converting class components to functional ones, and we'll go file-by-file keeping the app's functionality intact while upgrading it to use hooks - including custom hooks, and the Context API. 

- Module 4: Classes to functions - we'll take every class component and turn it into a functional component.
- Module 5: [Custom hooks](https://reactjs.org/docs/hooks-custom.html) - we'll identify where custom hooks can simplify our functional components further.
- Module 6: [Context API](https://reactjs.org/docs/context.html) - a few strategically placed React contexts will round out our code improvements.

### Part three: testing

An updated application is only half the battle for enterprise-level apps; development teams must also be confident in their continued success as the apps expand in size and scope. 

We'll add automated testing to our app using the widely accepted testing frameworks React Testing Library and Cypress.

- Module 7: Integration testing - the popular combination of [Jest](https://jestjs.io/) and [React Testing Library](https://testing-library.com/docs/react-testing-library/intro/) will be used to unit test smaller pieces of our app.
- Module 8: End-to-end testing - the ease of writing e2es with [Cypress Studio](https://www.cypress.io/) will blow you away.

### Bonus: design systems

Finally, I've included a special bonus module about how to incorporate design systems into an already existing application, and switch out components in a systematic way. Design systems and component libraries are quickly gaining ground - especially in big orgs with lots of apps and development teams. 

Being able to effectively use one is an important skill to learn.

- Module 9: [Ant Design](https://ant.design/) - we'll swap in the robust design system's components to handle our app's more complex interactions for us.

![Product page of the Hardware Handler sample React application](https://d2uusema5elisf.cloudfront.net/courses/newline-guide-to-modernizing-an-enterprise-react-app/module_10/lesson_00.00/public/assets/hardware-handler-product-page.png)

## Bottom Line

In 10 modules, we'll go step-by-step taking an app from outdated in every way to up to today's high standards, giving you ample practice and hands-on examples along the way. 

If you've been wanting to get more confident in your React skills _and_ see what it takes to build enterprise apps in today's world, this is the course for you.

![Checkout page of the Hardware Handler sample React application](https://d2uusema5elisf.cloudfront.net/courses/newline-guide-to-modernizing-an-enterprise-react-app/module_10/lesson_00.00/public/assets/hardware-handler-check-out.png)

In this course, you'll learn all the pieces that go into modernizing an existing React application so it can take advantage of the latest framework features and run well for years to come.

The newline Guide to Modernizing an Enterprise React App

How to modernize an existing React application according to today's standards

How React Hooks work compared to class components

How config tools Volta and Node engines simplify development

How to set up ESLint and Prettier to improve code quality

How to upgrade an existing React app and refactor the app as you go

How to write integration tests with React Testing Library to ensure app functionality

How end-to-end tests with Cypress can test mission critical user flows

How to incorporate a component library to speed up design and development time

We've made it to the last lesson in this module — hurray! And I have a feeling you're really going to like this lesson because Cypress has gone and done what developers for years have wished was possible with testing: it's made it possible to 

 feature is still in experimental mode at the time I'm writing this, but hopefully, it will be out of experimental mode in the not too distant future.

For this lesson, we'll enable Cypress Studio and learn how to 

 Cypress what we'd like it to test instead of having to write all the test code ourselves. It's pretty cool and speeds up test writing time by leaps and bounds.

Enable the experimental Cypress Studio in our app

As I said, Cypress Studio is not fully out of beta mode yet, so in order to take advantage of it, we'll need to add a special flag in our app.

 variable a few lessons ago, and add the following line to our file.

{
  "baseUrl": "http://localhost:3000",
  "experimentalStudio": true
}

, we're ready to start using Cypress Studio. Easy enough to enable it, right?

The first step, just as it was for our other e2e tests, begins with determining what we want to test and making a test file for that particular flow.

For this test, another important functionality in Hardware Handler is that a user should be able to add products to the checkout when they go the 

. This is where we'll tell Cypress Studio to write our new test adding items to the checkout.

Right after creating this file, we'll set up a 

 block to contain our test. Keep the initial 

 simple. Our test will drill down into the details soon enough.

describe('Add products to checkout', () => {});

Mock our data and API calls for the department and product APIs

Before we can show Cypress how we want it to test, we need to set up a few mocks and some data for it to use whenever the test runs.

 component, you'll see that when the component loads, it needs data from the 

 — so we'll need to mock data for both of those to serve up for this test.

We already have the mocked department data we need from our last lesson, so it's a matter of just importing that mock. Create a 

, and we'll start it off very similar to the one we did in our last lesson for the 

import * as departmentMocks from '../support/service_mocks/department_mocks';

describe('Add products to checkout', () => {
  beforeEach(() => {
    cy.visit('/');
    cy.server();
    cy.fixture('department_data.json').then((rc) => {
      departmentMocks.getAllDepartments(rc.departments);
    });
  });

 will bring us to the landing page of Hardware Handler, and then the combination of 

 will ensure that any HTTP calls made to the department API's 

 function will be intercepted and the mocked data in our 

Next, we must create data and a mock for the product API's 

 request, its setup is practically identical to the 

 mock call we already defined above it, but it doesn't even need to accept any arguments beyond a 

Here's how that API call mock should look.

export const getAllProducts = (response, status = 200) => {
  cy.route({
    method: 'GET',
    url: '/products',
    response,
    status,
  }).as('getAllProducts');
};

Our new product mock needs some product data to supply when it's called, so once more, we'll open up our 

This file will hold an array of mocked product data, and each 

 object will have the following properties: 

---
title: 'Getting The Most Out Of Cypress.io's Studio Feature During Testing'
role: 'LESSON'
description: "The Studio feature makes e2e test writing faster and easier than it's ever been before."
privateVideoUrl: https://fullstack.wistia.com/medias/al3w9rtr4u
isPublicLesson: false
code: https://gitlab.com/fullstackio/books/newline-course-apps/paige-niedringhaus-modernizing-an-enterprise-react-app-app/-/tree/main/code/module_09/lesson_09.02/protected/source_code/hardware-handler-8-ending?ref_type=heads
---

# Try out Cypress Studio

We've made it to the last lesson in this module — hurray! And I have a feeling you're really going to like this lesson because Cypress has gone and done what developers for years have wished was possible with testing: it's made it possible to _show_ an e2e how it should conduct a test.

This [Cypress Studio](https://docs.cypress.io/guides/core-concepts/cypress-studio) feature is still in experimental mode at the time I'm writing this, but hopefully, it will be out of experimental mode in the not too distant future.

**For this lesson, we'll enable Cypress Studio and learn how to _show_ Cypress what we'd like it to test instead of having to write all the test code ourselves. It's pretty cool and speeds up test writing time by leaps and bounds.**

### Enable the experimental Cypress Studio in our app

As I said, Cypress Studio is not fully out of beta mode yet, so in order to take advantage of it, we'll need to add a special flag in our app.

Open the `cypress.json` file where we added the `baseUrl` variable a few lessons ago, and add the following line to our file.

```json  { actualFilename=../lesson_09.02/protected/source_code/hardware-handler-8-ending/client/cypress.json endChar=71 endLine=5 startChar=0 startLine=1 statedFilename=client/cypress.json url=https&#x3A;//gitlab.com/fullstackio/books/newline-guide-to-modernizing-an-enterprise-react-app/module_09/lesson_09.04/.lesson_09.02/protected/source_code/hardware-handler-8-ending/client/cypress.json }
{
  "baseUrl": "http://localhost:3000",
  "experimentalStudio": true
}
```

With this line of `"experimentalStudio": true;`, we're ready to start using Cypress Studio. Easy enough to enable it, right?

#### Test a user can add products to checkout

The first step, just as it was for our other e2e tests, begins with determining what we want to test and making a test file for that particular flow.

For this test, another important functionality in Hardware Handler is that a user should be able to add products to the checkout when they go the **My Products** page. Let's get to it.

**Make a new `add_products_to_checkout_spec.js` file**

Inside of the `integrations/` folder, make a new file named `add_products_to_checkout_spec.js`. This is where we'll tell Cypress Studio to write our new test adding items to the checkout.

Right after creating this file, we'll set up a `describe` block to contain our test. Keep the initial `describe` simple. Our test will drill down into the details soon enough.

```javascript
describe('Add products to checkout', () => {});
```

**Mock our data and API calls for the department and product APIs**

Before we can show Cypress how we want it to test, we need to set up a few mocks and some data for it to use whenever the test runs.

If you look at our actual `<ProductList>` component, you'll see that when the component loads, it needs data from the `departmentApi` and from the `productApi` — so we'll need to mock data for both of those to serve up for this test.

We already have the mocked department data we need from our last lesson, so it's a matter of just importing that mock. Create a `beforeEach` where we'll set up these mocks.

Right inside of the `describe`, make a `beforeEach`, and we'll start it off very similar to the one we did in our last lesson for the `add_new_product_spec.js` file.

```javascript
import * as departmentMocks from '../support/service_mocks/department_mocks';

describe('Add products to checkout', () => {
  beforeEach(() => {
    cy.visit('/');
    cy.server();
    cy.fixture('department_data.json').then((rc) => {
      departmentMocks.getAllDepartments(rc.departments);
    });
  });
```

Just like before, `cy.visit` will bring us to the landing page of Hardware Handler, and then the combination of `cy.server` and `cy.fixture` will ensure that any HTTP calls made to the department API's `getAllDepartments` function will be intercepted and the mocked data in our `department_data.json` file will be returned in its stead.

Next, we must create data and a mock for the product API's `getAllProducts` HTTP call.

**Add a new mock to our `product_mocks.js` file**

Open the `product_mocks.js` file inside of the `support/service_mocks/` folder and add a new function named `getAllProducts`.

Since `getAllProducts` is a `GET` request, its setup is practically identical to the `addNewProduct` mock call we already defined above it, but it doesn't even need to accept any arguments beyond a `response` and a `status`.

Here's how that API call mock should look.

```javascript { actualFilename=../lesson_09.02/protected/source_code/hardware-handler-8-ending/client/cypress/support/service_mocks/product_mocks.js endLine=17 startLine=10 statedFilename=cypress/support/service_mocks/product_mocks.js url=https&#x3A;//gitlab.com/fullstackio/books/newline-guide-to-modernizing-an-enterprise-react-app/module_09/lesson_09.04/.lesson_09.02/protected/source_code/hardware-handler-8-ending/client/cypress/support/service_mocks/product_mocks.js#L10 }
export const getAllProducts = (response, status = 200) => {
  cy.route({
    method: 'GET',
    url: '/products',
    response,
    status,
  }).as('getAllProducts');
};
```

**Create mocked product data**

Our new product mock needs some product data to supply when it's called, so once more, we'll open up our `fixtures/` folder where our `department_data.json` lives and create a new file named `product_data.json`.

This file will hold an array of mocked product data, and each `product` object will have the following properties: `id`, `name`, `brand`, `description`, `retailPrice`, `departmentId`.

Since our `department_data` mocks include departments for Patio Furniture and Flooring, I made product test data to match those two departments, but feel free to make your own substitutions for these products.

```json  { actualFilename=../lesson_09.02/protected/source_code/hardware-handler-8-ending/client/cypress/fixtures/product_data.json endChar=1468 endLine=53 startChar=0 startLine=1 statedFilename=cypress/fixtures/product_data.json url=https&#x3A;//gitlab.com/fullstackio/books/newline-guide-to-modernizing-an-enterprise-react-app/module_09/lesson_09.04/.lesson_09.02/protected/source_code/hardware-handler-8-ending/client/cypress/fixtures/product_data.json }
{
  "products": [
    {
      "id": 1,
      "name": "Cantilever Umbrella",
      "brand": "Backgate",
      "description": "The fanciest umbrella with an ultra strong curved arm so there is no pole marring your perfect view.",
      "retailPrice": 29000,
      "departmentId": 22
    },
    {
      "id": 2,
      "name": "Shag Rug",
      "brand": "Fauxhawk",
      "description": "You thought once was enough, but guess what? This rug is back for round 2.",
      "retailPrice": 6999,
      "departmentId": 37
    },
    {
      "id": 3,
      "name": "Table and Chair Set",
      "brand": "Backgate",
      "description": "What's a table without some chairs to match? Have a seat and enjoy.",
      "retailPrice": 18250,
      "departmentId": 22
    },
    {
      "id": 4,
      "name": "Arabesque Tile",
      "brand": "Tile & More",
      "description": "This is some seriously classy file flooring. Easy clean, easy install to boot.",
      "retailPrice": 1299,
      "departmentId": 37
    },
    {
      "id": 5,
      "name": "Area rug",
      "brand": "Carpets r' Us",
      "description": "This lovely area rug warms up any room instantly.",
      "retailPrice": 31799,
      "departmentId": 37
    },
    {
      "id": 6,
      "name": "Outdoor Chaise Lounge",
      "brand": "Sandy Furniture",
      "description": "Why sit up and when you can lounge by the pool living your best life?",
      "retailPrice": 23900,
      "departmentId": 22
    }
  ]
}
```