Learn Egghead, Jest and Twit

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

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

In this course we’ll learn how to create Twitter bots. We’ll first learn how to interface with the Twitter API using Twit.js, which allows us to post statuses, search tweets, and interact with followers. We’ll create several example bots that show the diversity of possibilities, using powerful tools such as RiTa.js, Google’s Cloud Vision API, and Tracery. We’ll learn how to tweet data from Google Spreadsheets, and to compose and tweet a song for an audio bot. We’ll also learn how to host our bot logic on Heroku and Docker. 

Twitter API Client for node

Supports both the REST and Streaming API.

twit

Create your own twitter bots

This is the video companion to the [egghead.io Instructor Guide](https://howtoegghead.com/instructor/).

Screencasting is hard! There are virtually infinite ways to produce one. For an egghead.io lesson we expect several key aspects to be met. We want to make sure that our lessons have depth and clarity. Clarity is important and starts with the technical aspects of recording your screen and voice. Once we have achieved this objective level of clarity, we dip into the stylistic aspects of recording a lesson. The style is subjective, and the goal of an egghead.io lesson is not to have an army of uniform drone producing flavorless video content for the masses.

Our mission is to make you a badass screencaster. We want to push you to another level. We've found that a small set of standard practices will create an awesome experience for the student, and eliminate frustration as we teach by providing a repeatable pattern for success. It’s not complicated. In fact, it is simple, but it isn’t easy.


This course will show you how to produce an egghead.io lesson. We strive for consistency in style, and these lessons will demonstrate the core elements that create our brand screencasts. Let’s learn how together.

Bite-size video tutorials for badass web developers.

egghead

Record Badass Screencasts for egghead.io

Miscellaneous one-off lessons on debugging, productivity hacks, and JavaScript tricks.

JavaScript® (often shortened to JS) is a lightweight, interpreted, object-oriented language with first-class functions, most known as the scripting language for Web pages, but used in many non-browser environments as well such as node.js or Apache CouchDB. It is a prototype-based, multi-paradigm scripting language that is dynamic, and supports object-oriented, imperative, and functional programming styles.

javascript

Tips and Tricks

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

The Chrome Developer Tools (DevTools for short), are a set of web authoring and debugging tools built into Google Chrome.

chrome-devtools

Your page is showing high CPU usage and spinning up your laptop fan, but nothing is visibly happening. What is it doing, and why is it so slow?

This lesson is a real-world performance diagnosis of this very page, right here on egghead. Two infinite (but hidden) animations were causing CPU usage to spike, and Chrome's Task Manager and Performance tools helped uncover the elements causing the problem. You'll see how to use the profiler to record a snapshot, and learn a trick for discovering animations running in the background.

Diagnose a Slow Page Using Developer Tools

codesandbox.io provides one of the fastest ways to start a new React project. In this lesson, we will take a first look at codesandbox, its interface, and the default React project it creates.

Use Codesandbox to Start a New React Application

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

By re-assigning a couple mouse buttons, you can drastically improve the speed you can edit your lessons in Screenflow. This lesson shows how to customize using the Logitech software, but the concept should work for any mouse customization software as well.

Faster Edits in Screenflow with Mouse Customizations

Sometimes you have an idea that you want to quickly record, but the idea of setting up a project just to get it recorded gets in your way. I'm going to walk your through scripting away the main setup pain points so that you can focus on creating content.

Automate egghead Lesson Setup with ZSH Shell Functions

When making your font sizes large, your code will often get to long to fit on the screen. This lesson shows you how to use "word wrap" or "prettier print width" to adjust your code to fit within the editor.

Reformat Code to Fit the Screen

To be useful and trustworthy, your CLIs should be extraordinarily reliable. Investing in testing early will reap rewards in future. We show how to set up basic tests with Jest and Oclif's test helpers.

Test Node.js CLIs with Jest and Oclif

Components do more than just render an initial view based on props. Components may also maintain their own internal state and update that state in response to events. Those state changes, will then lead to updates to the rendered output. In this lesson, we'll cover how to test a component and verify that it behaves as expected when we simulate a click event.

Test Component Interactions with Jest and Testing Library

As the core unit of functionality in a React application, our components should be tested. Using Jest and Testing Library, we can render our individual components right in a test context and make assertions about their rendered output and behavior. Tests are a great way to work through API decisions, provide living documentation for your code, and to allow for confidence when refactoring. In this lesson, we'll create an initial test to verify the initial rendered output for a component, given specific props.

Test Component Rendering with Jest and Testing Library

Our unit tests should never rely on code that is outside our control and they certainly shouldn't be calling across the network to a server. A good test needs to be repeatable and fast and relying on outside systems and/or data doesn't help us meet those goals. In this lesson, we'll use mocks to create an environment where we control the response for service calls. This will allow us to be confident in our assertions and ensure our tests aren't flaky.

Mock Modules in a React Component Test

Any time your test interacts with a React component in a way that results in a state update, you need to make sure you wrap that interaction in an `act` function call, otherwise you'll get the "not wrapped in act(...)" warning.

In this lesson you'll learn how you can use `act` with `@testing-library/react-hooks` to avoid potential bugs in your custom React hooks.

This is based on my blog post: [Fix the "not wrapped in act(...)" warning](https://kentcdodds.com/blog/fix-the-not-wrapped-in-act-warning)

Fix the "not wrapped in act(...)" warning when testing Custom Hooks

The dreaded `act(...)` warning is really annoying, but actually really important. I've yet to see it be wrong (even when I thought it must be!). Every time it's pointing out something that is important that I'm missing in my test. In this lesson we'll identify a missing piece to our test and use act to make sure we avoid that in the future.

This is based on my blog post: [Fix the "not wrapped in act(...)" warning](https://kentcdodds.com/blog/fix-the-not-wrapped-in-act-warning)

Fix the "not wrapped in act(...)" warning

There aren't many places you need to manually use `act` if you're using [React Testing Library's async utilities](https://testing-library.com/docs/dom-testing-library/api-async), but if you're using fake timers, you need to manually use `act` to avoid missing bugs in your code.

In this lesson you'll learn how to identify the cause of `act` warnings and how to resolve them.

This is based on my blog post: [Fix the "not wrapped in act(...)" warning](https://kentcdodds.com/blog/fix-the-not-wrapped-in-act-warning)

Fix the "not wrapped in act(...)" warning with Jest fake timers

Use cases for `useImperativeHandle` are few and far between, but if you're testing a component that uses this React hook, you need to wrap any function you expose which results in state updates when called in React's `act` utility. Otherwise you could be missing important things in your tests that could result in bugs shipped to production.

In this lesson we'll learn how to identify what needs to be wrapped in `act(...)` and how to wrap those interactions.

This is based on my blog post: [Fix the "not wrapped in act(...)" warning](https://kentcdodds.com/blog/fix-the-not-wrapped-in-act-warning)

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