Learn Cypress, Jest and Ngrx-store

Imagine the following.

You join a new project and after getting access to the repo you notice that there's no tests.

You decide to ask the team whether they are in different repo or something and unfortunately the answer is:

>We don't have any tests, we didn't have the time.

😐

In this collection we're going to learn how to add e2e tests with cypress.io to an existing React app in order to do two things:

- 🌟 Ensure that our app currently works as intended
- 🌟 Allow us to add features to it with a technique called "Cypress Driven Development" 

In less than 20 minutes we're going to go through:

- ⚡️Adding cypress.io setup to an existing project
- ⚡️Testing search functionality with `data-cy` properties
- ⚡️Using "Cypress Driven Development" to add a new feature to an app
- ⚡️Use Cypress UI to debug an API response
- ⚡️How to use `cy.only` and `cy.skip` in order for us to build our e2e test suite faster

and much more!

Fast, easy and reliable testing for anything that runs in a browser.

cypress

Add e2e tests with cypress to a React application

One of the most important — but most ignored — practices for web developers is performing end-to-end testing on applications before they go live into production. You know: making sure they work like they’re supposed to. But testing can be tedious, and definitely not fun.

In this course, Brett Cassette will show you how you can test all layers of your application stack, simultaneously, with Cypress. When you use Cypress, it’s like having a robot that uses your app the way a real user would. Cypress reports if things work the way you designed them to — and if they don’t — every step of the way. And it’s fun.

After completing this course, you’ll be ready to apply the same E2E testing principles to your own applications. Stop leaning on your QA department (if it exists) to stress-test your application, and ship your app knowing it’s ready. 


Test Production Ready Apps with Cypress

As your Angular application grows, it becomes more difficult to manage application state.

NgRx can help with that!

In this course, we will learn how to convert an Angular application from using stateful services into using NgRx.

We will accomplish this by adding a new feature, including building a reducer and actions. We'll also touch on using selectors to query our state, managing collections with NgRx entity, async operations, and hiding implementation details with the facade pattern.

Angular is a development platform for creating applications using modern web standards. Angular includes a wealth of essential features such as mobile gestures, animations, filtering, routing, data binding, security, internationalization, and beautiful UI components. It's extremely modular, lightweight, and easy to learn.

angular

Reactive State Management in Angular with ngrx

In this collection, we build a minimal flashcard application using React, primarily focusing on function components and the hooks API. To make sure we can understand and maintain existing code, there are also a few lessons toward the end that use class components so you can get familiar with the syntax. We cover important React concepts, and sprinkle in libraries that are pretty standard in the ecosystem like @reach/router, Jest, and React testing library. We start with create-react-app so we can get right into it without worrying about configuring tooling. There's [a separate course for that here](https://egghead.io/courses/modern-javascript-tooling-with-react?af=5mx0ie)

jest

Build a React App with the Hooks API

The tools available for unit testing have come a long way. While testing may never be “easy”, the available tools have certainly moved testing closer to the simple end of the spectrum. Full end to end testing hasn’t quite kept the same pace and as a result many applications are testing manually and often by users in production. Cypress provides a testing environment that makes end-to-end testing fast and reliable with a simple API that makes creating automated unit tests for your web applications a no-brainer.


End to End testing with Cypress

In this course we are going to work through properly setting up Enzyme with Jest to test rendered components. This includes the nitty gritty of making our testing environment work with various versions of React. After we get our environment setup ready, we’ll work through the different ways we can render a component within our test pages. With a rendered component we can now test component methods and properties to assert that they are what is intended. 

React is one of the web’s most popular frameworks for building JavaScript applications. 

If you know what you’re doing, React can drastically simplify how you build, use, and maintain code.

Whether you’re a React newbie or you’re ready for advanced techniques, you can level-up with egghead. Explore our in-depth courses, lessons, and community resources to build more powerful applications and crack open your career.

react

Test React Components with Enzyme and Jest

End-to-end testing assures you of a few things: that all the integrated pieces of an application properly function, all those pieces work together as expected, and your tests include and simulate real-user scenarios — something unit and integration tests just don't do.

This course introduces you to two great tools for E2E testing: 

* Puppeteer opens and runs applications in a Chromium browser and performs the actions it's given.
* Jest asserts that the integrated pieces work as expected and that add-on libraries like Faker and pixelmatch take our tests to the next level.

Over 9 lessons, we will create common application features and use Puppeteer and Jest to run different types of tests against them. You'll get practice using these tools to render content, mimic user activity, automate tests, and measure the overall performance of your application.

End to End Testing with Google's Puppeteer and Jest

***Note: RxJS imports have changed since the publication of this course. The concepts being taught on RxJS are still applicable.**

Angular has many built-in features for working closely with RxJS to help you build entirely reactive applications. This course will teach you how to use Angular with RxJS. We will learn how to use the ngrx/store library to manage state in a clean, reactive "Redux style."

This course assumes you've got a working knowledge of Angular and reactive programming with RxJS. If you don't, you might want to watch the following courses to get you up to speed! 
- [Get Started with Angular](https://egghead.io/courses/get-started-with-angular) 
- [Introduction to Reactive Programming with RxJS](
https://egghead.io/series/introduction-to-reactive-programming). 
- [Step by Step Async Programming with RxJS](https://egghead.io/series/step-by-step-async-javascript-with-rxjs) 
- [Getting Started With Redux](https://egghead.io/series/getting-started-with-redux), a course by Redux's, Dan Abramov.

We also have Intermediary Angular courses if you'd like to acquire more in-depth knowledge. 
- [Dependency Injection](https://egghead.io/courses/angular-2-dependency-injection-di-explained
- [Components, Directives](https://egghead.io/courses/building-angular-components)
- [Forms](https://egghead.io/courses/intro-to-angular-forms)
- [Router](https://egghead.io/courses/intro-to-angular-router)
- [Animating Web Apps](https://egghead.io/courses/animate-angular-web-applications)



Build Redux Style Applications with Angular, RxJS, and ngrx/store

Here are all the Egghead.io lessons about testing with Jest! http://facebook.github.io/jest (https://kcd.im/egghead-jest)

Testing JavaScript with Jest

Kent walks us through the internals of dom-testing-library and react-testing-library. 

There is a lot of set-up and tear down when testing UI components. These two libraries take away a lot of the work required to test React components well. 

Jest is commonly used in tandem with react-testing-library to assert results of your components. Jest simulates most browser apis with jsdom. react-testing-library helps you get values out of your components the same way your end users will. 

Links from the show:
- [Testing Library](https://testing-library.com)
- [Testing Javascript](https://testingjavascript.com)
- [Unit vs Integration vs E2E](https://kentcdodds.com/blog/unit-vs-integration-vs-e2e-tests)
- [Why you shouldn't ReactDOM.render to the body](https://medium.com/@dan_abramov/two-weird-tricks-that-fix-react-7cf9bbdef375)
- [Effective Snapshot Testing]( https://kentcdodds.com/blog/effective-snapshot-testing/)
- [Dev Tips with Kent](https://youtu.be/ttmvAm6esSc)
- https://kcd.im/news

Understanding how react-testing-library works with Kent C. Dodds

So you have a production application, and it doesn't use Cypress yet.

In this course, you'll learn how to add Cypress to your existing npm application, and run it for the first time.

Recommended Homework: 
- Look through the tests Cypress spins up for you and learn how typical Cypress tests are setup

Install Cypress in a Production Application

Using cy.server, cy.route, and cy.wait, we can intercept requests to our real backend, and return known mock responses.

The pros of using this approach:
- It's much faster than interacting with the real backend
- Doesn't need to seed data to the backend
- Easy control of requests and responses
- Can mock network delay and failure

Cons:
- No guarantee the stubs match the real backend responses
- Not full end-to-end testing

Recommended Homework:
- Mock the route to create a new todo, and reply with a 200
- Mock the route to edit an existing todo, and reply with a 200

Mock Your Backend with Cypress

Cypress can do more than end-to-end testing. It can fully drive remote applications, including ones you don't own, much more reliably than Selenium.

In this example, we'll use Cypress to build a web scraper to mine data from applications we don't own. This data could be used to power other applications, filtered for data relevant to your use cases, sent to your calendar, or any number of uses. 

Since Cypress is easy to automate, it's easy to integrate with cron or a job framework to run a scraper in an automated fashion.

Create a Web Scraper with Cypress

We can reuse our stubbed responses between tests by using Cypress fixtures. In this lesson, learn how to share data between tests.

Reuse Data with Cypress Fixtures

Learn how to setup your [Cypress development environment](https://docs.cypress.io/guides/tooling/intelligent-code-completion.html#Reference-type-declarations-via-tsconfig) with Intellisense, custom Cypress configuration in cypress.json, and [get settings autocompletion in VSCode](https://docs.cypress.io/guides/tooling/intelligent-code-completion.html#Set-up-in-your-Dev-Environment-1).  

Recommended Homework:
- Setup your Cypress dev environment

Setup Your Cypress Dev Environment

If we want to do full end-to-end testing, then we need to seed our database into a reliable state at the start of every test. In this lesson, we'll learn how to build a Cypress plugin that updates the data in our database.

Seed Your Database in Cypress

Learn how to target the elements on your UI, interact with them, and make assertions on their state.

Recommended Homework:
- Write a test that creates a new todo and asserts that the todo is present on the DOM
- Write a test that finishes a todo, and asserts that the todo shows as completed

Write Your First Cypress Integration Test

Which selectors your choose for your tests matter, a lot. In this lesson, we'll see the recommended Cypress best practices for selectors, and why we should prefer the data-cy attribute.

Recommended Homework:
- Finish the example using cy.contains, and remove the false positives to get a richer sense of why data-cy is a better choice for our selector

Use the Most Robust Selector for Cypress Tests

The Cypress programming model is similar to async and await. When you write Cypress commands, they will be enqueued to be run at a later time, but they will run in the same order as you write them. 

Recommended Homework:
- Verify that Cypress commands run in the order you write them, and not based on when they asynchronously finish. Recommended solutions include using timeouts, and/or synchronously available values as with cy.wrap


Debug and Log with Cypress

Cypress doesn't provide out-of-the-box ability to make assertions on our frontend stores, so let's expose the store to the tests, and assert on it. We'll use our knowledge of Cypress's asynchronous programming style to access properties and functions on the store using cy.its and cy.invoke.

Recommended Homework:
- Consider why it's valuable to test against your frontend store when you can test against the UI

Assert on Your Redux Store with Cypress

Do you need to reuse complex Cypress calls often (like when accessing the store)? 

You can turn them into custom Cypress commands, and even customize their output in the time-traveling debugger, so it's easy to see a snapshot at the point your command ran!

 Recommended Homework:
- Review the Best Practices for Custom Commands - https://docs.cypress.io/api/cypress-api/custom-commands.html#Best-Practices

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