Testing React Applications 🧐

👋 hi there! My name is Kent C. Dodds! This is a workshop repo to teach you about increasing your deploy confidence by using Jest and React Testing Library to test your react components.

Pre-Workshop Instructions/Requirements

NOTE: This repository is used for a two-part workshop

In order for us to maximize our efforts during the workshop, please complete the following things to prepare.

• 📺 only necessary if the workshop is remote via Zoom

• 👋 specific to the material for this workshop

• 👋 Setup the project (follow the setup instructions below) (~5 minutes)

• 📺 Install and setup Zoom on the computer you will be using (~5 minutes)

• 📺 Watch Use Zoom for KCD Workshops (~8 minutes).

• 👋 Watch The Beginner's Guide to React (available free on Egghead.io), or have the equivalent experience with React (147 minutes)

• 👋 Go through my Learn React Hooks Workshop, or have the equivalent basic experience of using hooks. You should be experienced with useState, useEffect, and useRef.

• 👋 Go through my Advanced React Hooks, or have the equivalent basic experience of using advanced hooks. You should be experienced with useContext, useReducer, useMemo, and useCallback.

The more prepared you are for the workshop, the better it will go for you.

System Requirements

• git v2 or greater
• NodeJS v10 or greater
• npm v6 or greater

All of these must be available in your PATH. To verify things are set up properly, you can run this:

git --version
node --version
npm --version

If you have trouble with any of these, learn more about the PATH environment variable and how to fix it here for windows or mac/linux.

Setup

After you've made sure to have the correct things (and versions) installed, you should be able to just run a few commands to get set up:

git clone https://github.com/kentcdodds/testing-react-apps.git
cd testing-react-apps
npm run setup --silent

If you get any errors, please read through them and see if you can find out what the problem is. If you can't work it out on your own then please file an issue and provide all the output from the commands you ran (even if it's a lot).

Running the app

To get the app up and running (and really see if it worked), run:

npm start

This should start up your browser. If you're familiar, this is a standard react-scripts application.

You can also open the deployment of the app on Netlify.

There's not much to it. The whole reason we have the app is just so you can see examples of the components that we'll be testing.

Running the tests

npm test

This will start Jest in watch mode. Read the output and play around with it. All the tests will start out in a passing state. Your job will be to follow the emoji's instructions to test the components using the tools and patterns described.

Workshop Outline

Let's get some rock-solid confidence in our React Apps! 💎

👋 I'm Kent C. Dodds

• 🏡 Utah
• 👩 👧 👦 👦 👦 🐕
• 🏢 https://kentcdodds.com
• 🐦/🐙 @kentcdodds
• 🏆 https://testingjavascript.com
• 🥚 https://kcd.im/egghead
• 🥋 https://kcd.im/fem
• 💌 https://kcd.im/news
• 📝 https://kcd.im/blog
• 📺 https://kcd.im/devtips
• 💻 https://kcd.im/coding
• 📽 https://kcd.im/youtube
• 🎙 https://kcd.im/3-mins
• ❓ https://kcd.im/ama

Schedule

• 😴 Logistics
• 💪 01. simple test with ReactDOM
• 💪 02. simple test with React Testing Library
• 😴 10 Minutes
• 💪 03. Avoid implementation details
• 💪 04. form testing
• 🌮 30 Minutes
• 💪 05. mocking HTTP requests
• 💪 06. mocking modules
• 😴 10 Minutes
• 💪 07. testing with context and a custom render method
• 😴 10 Minutes
• 💪 08. testing custom hooks
• ❓ Q&A

Questions

Please do ask! Interrupt me. If you have an unrelated question, please ask on my AMA.

Zoom (for remote workshops)

• Help us make this more human by keeping your video on if possible
• Keep microphone muted unless speaking
• Breakout rooms

Exercises

• src/__tests__/exercise/00.md: Background, Exercise Instructions, Extra Credit
• src/__tests__/exercise/00.js: Exercise with Emoji helpers
• src/__tests__/final/00.js: Final version
• src/__tests__/final/00.extra-0.js: Final version of extra credit

The purpose of the exercise is not for you to work through all the material. It's intended to get your brain thinking about the right questions to ask me as I walk through the material.

Helpful Emoji 🐨 💪 🏁 💰 💯 🦉 📜 💣 👨‍💼 🚨

Each exercise has comments in it to help you get through the exercise. These fun emoji characters are here to help you.

• Kody the Koala Bear 🐨 will tell you when there's something specific you should do
• Matthew the Muscle 💪 will indicate what you're working with an exercise
• Chuck the Checkered Flag 🏁 will indicate that you're working with a final version
• Marty the Money Bag 💰 will give you specific tips (and sometimes code) along the way
• Hannah the Hundred 💯 will give you extra challenges you can do if you finish the exercises early.
• Olivia the Owl 🦉 will give you useful tidbits/best practice notes and a link for elaboration and feedback.
• Dominic the Document 📜 will give you links to useful documentation
• Berry the Bomb 💣 will be hanging around anywhere you need to blow stuff up (delete code)
• Peter the Product Manager 👨‍💼 helps us know what our users want
• Alfred the Alert 🚨 will occasionally show up in the test failures with potential explanations for why the tests are failing.

Workshop Feedback

Each exercise has an Elaboration and Feedback link. Please fill that out after the exercise and instruction.

At the end of the workshop, please go to this URL to give overall feedback. Thank you! https://kcd.im/tra-ws-feedback

Contributors

Thanks goes to these wonderful people (emoji key):

Kent C. Dodds 💻 📖 🚇 ⚠️

This project follows the all-contributors specification. Contributions of any kind welcome!

License

This material is available for private, non-commercial use under the GPL version 3. If you would like to use this material to conduct your own workshop, please contact me at [email protected]