Learn Cloudflare, Jest and Rust

Cloudflare Workers let you write JavaScript Service Workers that run directly in Cloudflare's 200+ edge locations around the world.

With a Cloudflare Worker, you can modify your site's HTTP requests and responses, make parallel requests, and even reply directly from the edge.

Cloudflare Workers are written against a similar API to the W3C Service Workers standard. However, while Service Workers run inside the end user's browser, Cloudflare Workers run on Cloudflare's servers. This means that Cloudflare Workers can implement trusted code (which the client cannot tamper with), and will work no matter what browser the user is running.

In this course, Kristian Freeman will teach you how to build and deploy a Serverless API with Cloudflare Workers. By learning how to build your own serverless JSON APIs, you can effectively manage a highly-available backend for your projects, without needing to learn DevOps or manage services.

Cloudflare secures and ensures the reliability of your external-facing resources such as websites, APIs, and applications. It protects your internal resources such as behind-the-firewall applications, teams, and devices. And it is your platform for developing globally-scalable applications.

cloudflare

Build a Serverless API with Cloudflare Workers

In this course, Chris takes a README-driven approach to build out a Rust CLI that supports content authoring for a digital garden.

Specifically, you'll work through the first command for the CLI, writing files. You start by initializing a new Cargo binary crate through creating the `write` command that allows you to create files (and their contents) to the folder that you set. 

Step by step you'll learn about:
- Handling user input
- Error handling
- Rust Move semantics
- Rust Copy semantics
- Integration testing

...and more!

Rust is a systems programming language that runs blazingly fast, prevents segfaults, and guarantees thread safety.

rust

Creating a Digital Garden CLI with Rust

Cloudflare Workers is a serverless application platform that enables you to create and deploy functions to Cloudflare's Edge Network.

Unlike other serverless providers that only have regional data centers, Cloudflare's Edge Network consists of hundreds of servers all over the world.

Cloudflare Workers is a powerful platform, and this course serves as a great introduction for what it can do.

Follow along with Kristian Freeman as you build a localization engine that renders data based on the Edge location nearest to the application's user.

After this course, you'll be ready to start experimenting with your own Cloudflare Workers projects. *Need an idea?* *[Check out the suggested Portfolio Project for this course.](https://egghead.io/projects/introduction-to-cloudflare-workers)*

Introduction to Cloudflare Workers

Rust is a modern language that is close to the metal. It's got the performance of C, but with a more friendly syntax and community.

It's also memory safe, and ensures your applications are bug free by catching errors at compile time instead of runtime.

These features make Rust a great choice for developing code for embedded systems, web servers, and CLI apps. You can even compile Rust into WebAssembly in order to run it in-browser!

But as the saying goes, "before you learn to run, you must learn to walk".

In this course, you will write your first Rust application.

Starting from “Hello World” you’ll quickly move on to learning about Rust’s types, configuration files, and the `cargo` package manager along with classics like functions, loops, and handling user input.

More Rust-specific concepts like macros and pattern matching will also be introduced.

Check out these [**community notes for this course on Github**](https://github.com/eggheadio-projects/write-your-first-program-with-the-rust-language).

Next Steps: [Basic Types in Rust](https://egghead.io/playlists/data-types-in-rust-ab72)

Write Your First Program with the Rust Language

[Rustlings](https://github.com/rust-lang/rustlings) is a set of exercises that serves as a great introduction to the Rust language. It covers many concepts from the [Rust book](https://doc.rust-lang.org/book/) by asking you to work through sets of exercises.

This collection walks you through Rustlings in a way that explains what's going on in each exercise. We cover everything from basic types to generics and threading.

Learning Rust by Working Through the Rustlings Exercises

This collection contains videos that explore the basic types in Rust, including **Fixed size Integer**, **Pointer sized Integer**, **Boolean**, **Strings**, **Characters**, **Arrays**, **Tuples** and more.

If you're just starting out learning Rust and [wrote your first program](https://egghead.io/courses/write-your-first-program-with-the-rust-language), this collection is the right place to get more familiar with the language!

Basic Types in Rust

Many languages work on a compilation story to WebAssembly, but Rust is already ready for primetime. Why?


- Rust is a stable language and great replacement for C and C++. 
- Due to the reference and borrowing concept, Rust doesn’t need a Garbage Collector and can be used for a production-ready WebAssembly project. 
- The Rust/Wasm team has built some sophisticated tooling for straightforward interoperability between Rust and JavaScript.

This course gives you the tools to compile to WebAssembly with Rust. Over 11 lessons, we’ll set up a project and explore various paths of communication and interoperability between Rust and JavaScript.

Using WebAssembly with Rust

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.

jest

End to End Testing with Google's Puppeteer and Jest

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)

Build a React App with the Hooks API

Best practices for building & testing redux applications have changed dramatically over time. This course aims to be a comprehensive and up-to-date resource for those seeking to confidently test their redux apps. Whether you're just getting started or want to improve on your existing testing strategy, there will be something in this course for you.

This first few lessons of this course look at how to add jest to an existing react/redux application that was built on top of [vite](https://vitejs.dev/). We cover basic functionality like using `npm test` vs `npx jest` and generating and using [code coverage](https://jestjs.io/docs/cli#--coverageboolean) to inform our testing strategy.

The next 10 or so lessons cover the specifics of unit testing the redux code in our application. We'll go over how to test reducers, selectors and thunks. As part of this we'll touch on mocking APIs and using [Redux Mock Store](https://github.com/reduxjs/redux-mock-store) as well as running actions through our applications' actual reducers to broaden our test coverage.

In the final part of this course we'll look at how we can test our redux connected react components using the various utilities that come with the [React Testing Library](https://testing-library.com/docs/react-testing-library/intro/). We'll cover simulating various kinds of user input with the [User Event Module](https://testing-library.com/docs/ecosystem-user-event), populating our redux store with test data, using [jest spies](https://jestjs.io/docs/jest-object#jestspyonobject-methodname), how to wait for asynchronous tasks to complete, and several approaches for finding & asserting that visual elements exist on the page.

This course is built on top of content that was created for the [Modern Redux with RTK and TypeScript](https://app.egghead.io/playlists/modern-redux-with-redux-toolkit-rtk-and-typescript-64f243c8) course and I highly recommend you start there if you haven't completed it already. It does expect a *basic* familiarity with react, redux and jest. TypeScript is used in these lessons, but is not a major focus and hopefully won't distract you too much if you prefer plain JavaScript.

No matter your experience level with redux and testing react applications, I'm confident your abilities will level up as you watch this course and follow along with the examples.

Thank you!

Confidently Testing Redux Applications with Jest & TypeScript

The Edge is one of the most exciting new topics in web development. At the front of the pack is Cloudflare, whose network boasts servers located in hundreds of cities all over the world instead of in regions like "East" or "West".

More servers in more locations mean a faster experience for your users.

But what about the data part of the equation?

If the application you're working on skews more toward "reading" rather than "writing" data, Cloudflare Workers KV is a perfect fit.

Once you create a KV namespace— the "KV" stands for "key-value"— Cloudflare keeps track of your application data. The most commonly accessed data will be propagated around the world to the various Edge servers, while less popular data will be stored in more central locations.

Kristian Freeman has produced courses that introduce how to build and deploy sites and JSON APIs powered by Cloudflare Workers.

Today, he will show you how Workers KV can be integrated into a Cloudflare Workers project through building a Todo App.

## The Project

![todo-app-screenshot](https://res.cloudinary.com/dg3gyk0gu/image/upload/v1639014074/course-resources/Build-data-driven-applications-on-the-edge-with-Workers-and-Workers-KV/CleanShot_2021-12-08_at_16.46.39_2x.png)

Before you groan about a bland Todo App, think about it this way: 

The Todo App is the perfect example of the CRUD operations. Cloudflare KV has its own nuances for reading and writing data through a concept called Binding that is easier to grok when you understand the larger example as a whole.

As the course progresses, Kristian shares examples of how you can store more complex key-values, along with data operations like editing and filtering.

One of the coolest features that Cloudflare KV allows for is user-specific data that is tied to the IP address the request originates from. In other words, you'll be able to share your deployed Todo app with anyone around the world, and they will only see their personal items.

## **Gain these Skills**

- Manipulating data using Cloudflare Workers KV
- Make data unique to each user without logging in
- Effectively store lightweight data in Cloudflare Workers KV
- Setting up a key-value store and connected projects
- Reading and writing to a serverless key-value store
- Storing complex values in a Cloudflare KV store

## **Prerequisites**

You'll need to have a basic understanding of what Cloudflare Workers is recommended but not necessary. This course is relatively beginner-friendly into the world of Workers KV that you can get by with no knowledge on Cloudflare Workers. 

But if you want to get the most out of this course, we would recommend taking [Introduction to Cloudflare Workers](https://egghead.io/courses/introduction-to-cloudflare-workers-5aa3) to get a better understanding of how Workers KV comes into play. 

## **What's Next? (You might also like these resources:)**

Follow along with Kristian Freeman as you build a localization engine that renders data based on the Edge location nearest to the application's user. → [Introduction to Cloudflare Workers](https://egghead.io/courses/introduction-to-cloudflare-workers-5aa3) 

Learn how to build your own serverless APIs so you can manage a highly available backend for your projects. No Learning DevOps or managing services necessary. →  [Build a Serverless API with Cloudflare Workers](https://egghead.io/courses/build-a-serverless-api-with-cloudflare-workers-d67ca551)

Using Cloudflare Pages and Cloudflare Workers, it's easy to create dynamic front ends that you can deploy in just seconds from GitHub. → [Deploy Dynamic Frontend Applications with Cloudflare Pages](https://egghead.io/courses/deploy-dynamic-frontend-applications-with-cloudflare-pages-6aaa00a1)

Build Data-Driven Applications on the Edge with Workers and Workers KV

Jest is a painless JavaScript unit testing framework from Facebook. It is designed to be super easy to setup and is packed full of powerful features. In this lesson we see how easy it is to add to your TypeScript project. This will be followed by a quick example application.

Getting started with Jest using TypeScript

React Storybook allows for easy snapshot testing integration with Facebook's Jest testing framework. Snapshot testing allows you to capture the state of your UI and then notify you when that UI has been altered. We can easily create and update snapshots with Storybook!
 




Jest Snapshot Testing with React Storybook

The reducer is at the center of how Redux manages state. In this lesson we’ll create a reducer function and see how Redux takes in state and actions and returns updated state. We’ll write and run unit tests using Jest to verify that our reducer function is working as expected.

Create a Redux-Style Reducer Function

In this lesson we are going to set up our basic app, set our environment variables, define our targeted viewport, and install Jest, Puppeteer, and Faker. We'll use these features to write our end to end tests. 

Setup and Install Dependencies for Testing with Google's Puppeteer

Now that we have our setup and environment ready for using Puppeteer to test our create-react-app, we can write our first tests. We will test our h1 and navigation, to make sure that they load correctly. In this lesson, we will be able to watch puppeteer open up a browser and evaluate our tests in real time. 

Test HTML Content on a Webpage with Puppeteer

In this lesson we are going to test a form submission by replicating keyboard input, mouse clicks, and touchscreen events. This will be done with random user information generated by Faker. We will test this in different contexts, including an iPhone 6 environment.

Replicate User Activity with Faker and Puppeteer

In this lesson we are going to test that a cookie is saved to the document whenever our login form is submitted. Then we will also learn how to set cookies from within our tests. 

Work with Document Cookies in Tests with Puppeteer

In this lesson we are going to write two tests that check our application for any console logs an page errors. We will also learn how we can log these out to our terminal. 

Check for Console Logs and Exceptions with Puppeteer

In this lesson we are going to take a screenshot and a pdf of our application. We'll add this to conditionally run when one of our tests fail. This way we can see what our test was seeing when it failed. These screenshots can help debug why tests fail. 