Learn Cypress, Http and Mobx

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

Developing logic-rich applications is a key skill to have.

The TypeScript–React combination helps you unlock that skill, and it’s a great developer experience in terms of writing understandable and refactorable HTML. But the default state management for React has a long way to go to feel simple and maintainable — and that’s where MobX makes your life so much easier. MobX keeps things simple without using complicated setups like `provider` and `connect` that provide way too little value for all the mental overhead. 

In this course, you’ll see how to model your React application logic using simple JavaScript classes — and with the help of MobX, make those classes the beating heart of your React applications. You’ll learn:

- that you don't need advanced annotations and TypeScript features to use MobX
- how to easily refactor code through TypeScript
- how to use TypeScript to track the flow of state as properties change

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

Develop React Applications with Mobx and TypeScript

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

MobX State Tree (MST) is a library that helps you organize your application states in a very structured manner. It allows you to create a component model, but for your data!

Course instructor Michel Weststrate—creator of Mobx—will teach you to model application state after your problem domain with MST. You will get hands-on practice and see how MST lets you solve problems with its out-of-the-box support for asynchronous actions, patches, snapshots, and middleware.

Over the 17 lessons, you’ll build a little bookshop application using React, MST, and create-react-app, while learning how to manage the lifecycle of your data by describing data models. 

Join Michel in one of the most popular courses on egghead!

Manage Application State with Mobx-state-tree

In this course, we will learn the fundamentals of the Hypertext Transport Protocol (HTTP) by exploring several popular HTTP APIs such as the GitHub API. Starting with the basic structure of an HTTP request and response, we will then delve into the specifics of each element of the request/response messages. Using concrete examples from these APIs, we will cover request methods, response status codes, messages headers, and message bodies. Along the way, you'll learn about specific message headers, such as `Cache-Control`, and `Cookie`  and how they control the behavior of clients/browsers and HTTP API services.

This course uses HTTPie, if you would like to follow along with the instructor you can download the client [here](https://httpie.org/).

The Hypertext Transfer Protocol (HTTP) is an application-level protocol for distributed, collaborative, hypermedia information systems. It is a generic, stateless, protocol which can be used for many tasks beyond its use for hypertext, such as name servers and distributed object management systems, through extension of its request methods, error codes and headers.

http

Understand the Basics of HTTP

MobX is designed to enable building web applications with a complex data model in an intuitive and very performant manner. Using React and MobX is currently the simplest way to build component based web applications.

"Half the code, twice the fun" is how people describe MobX, or "So simple, I cannot believe it just works". 



Manage Complex State in React Apps with MobX

As developers, we're often working closely with APIs to make requests in the browser or on the backend with a server, but we might not always know exactly how those requests work or how they should look.

Postman is a tool that lets us create, manage, and test API endpoints all within a UI so we can wrangle our APIs and understand how they work.

Create, Manage, and Test API Requests with Postman

Since MST offers a runtime type system, it can create and compose types on the fly, making it possible to reuse logic in new and powerful ways.

In this lesson you will learn:
* That MST types are immutable and composed together behind the scenes
* How to compose types explicitly by using `types.compose`
* How to create dynamic, parameterized types by leveraging that MST types are first class javascript citizens

Create Dynamic Types and use Type Composition to Extract Common Functionality

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

Create Custom Cypress Commands

External libraries tend to be synchronous, so how do we integrate other powerful tools into the Cypress framework? This lesson walks us through merging in the Lodash library to Cypress to allow us to slice and dice data to more accurately assert on just the pieces of data we care about.

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