Testing Node.js Backends

👋 hi there! My name is Kent C. Dodds! This is a workshop repo to teach you how to test your Node.js Apps!

TestingJavaScript.com

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Prerequisites

• Have fundamental understanding and experience with automated testing and tools. (Additional learning material: But really, what is a JavaScript test? and But really, what is a JavaScript mock?)
• Have experience with modern JavaScript APIs and features.

System Requirements

• git v2 or greater
• NodeJS v12 or greater
• yarn v1 or greater (or 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
yarn --version # or 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

If you want to commit and push your work as you go, you'll want to fork first and then clone your fork rather than this repo directly.

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-node-apps.git
cd testing-node-apps
node setup

This may take a few minutes. It will ask you for your email. This is optional and just automatically adds your email to the links in the project to make filling out some forms easier.

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).

If you can't get the setup script to work, then just make sure you have the right versions of the requirements listed above, and run the following commands:

npm install
npm run validate

It's recommended you run everything locally in the same environment you work in every day, but if you're having issues getting things set up, you can also set this up using GitHub Codespaces (video demo) or Codesandbox.

App Intro

App Demo

This is the backend for Bookshelf. I recommend you play around with it a little bit to get an idea of the kind of data we're dealing with here.

Data Model

• User

  • id: string
  • username: string

• List Item

  • id: string
  • bookId: string
  • ownerId: string
  • rating: number (-1 is no rating, otherwise it's 1-5)
  • notes: string
  • startDate: number (Date.now())
  • finishDate: number (Date.now())

For convenience, our we return a book object on each list item which is the book it's associated to. You're welcome frontend folks!

/me wishes we could use GraphQL

• Book

  • id: string
  • title: string
  • author: string
  • coverImageUrl: string
  • pageCount: number
  • publisher: string
  • synopsis: string

Running the tests

npm test

This will start Jest in watch mode. Read the output and play around with it. You'll be working in the .exercise files.

Exercises

• src/**/__tests__/[title].md: Background, Exercise Instructions, Extra Credit
• src/**/__tests__/[title].exercise.js: Exercise with Emoji helpers
• src/**/__tests__/[title].final.js: Final version
• src/**/__tests__/[title].final.extra-#.js: Final version of extra credit
• src/**/[title].js: The source file that you'll be testing

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.

Here's the order of exercises we'll be doing as well as where you can find the markdown file associated with each.

1. 🏋 Testing Pure Functions: src/utils/__tests__/auth.md
2. 🏋 Testing Middleware: src/utils/__tests__/error-middleware.md
3. 🏋 Testing Controllers: src/routes/__tests__/list-items-controller.md
4. 🏋 Testing Authentication API Routes: src/__tests__/auth.md
5. 🏋 Testing CRUD API Routes: src/__tests__/list-items.md

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 🐨 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.

Troubleshooting

"node setup" not working

If you're confident that your system meets the system requirements above, then you can skip the system validation and manually setup the project:

npm install
npm run validate

If those scripts fail, please try to work out what went wrong by the error message you get. If you still can't work it out, feel free to open an issue with all the output from that script. I will try to help if I can.

Contributors

Thanks goes to these wonderful people (emoji key):

Kent C. Dodds 💻 📖 🚇 ⚠️

Justin Dorfman 🔍

Andrew Mason 📖

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]

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/tna-ws-feedback