@sumup/cra-template

A create-react-app template for JavaScript React apps with SumUp's frontend stack.

Table of Contents

• 💻 Prerequisites
• ✨ Setting up a new JavaScript SumUp React project
• 🛠 Development workflow
  • Firing up the tools
  • Adding a new component
  • Linting your code
  • Writing tests
• 📖 Useful resources
• ⚠️ Troubleshooting
  • Debug mode
  • Broken build due to ESLint version
• Code of conduct (CoC)
  • Maintainers
• About SumUp

💻 Prerequisites

• You should have Node.js installed at a version equal or above v14.0.0. If you cannot do that, see the Troubleshooting section for ways around this requirement.
• At the moment this project reqires yarn (classic) to be installed on your system. Yarn is a package manager for JavaScript. You can read how to install the Yarn CLI in their documentation.

✨ Setting up a new JavaScript SumUp React project

1. Open your terminal.
2. Navigate to the directory you would like to place your project in.
3. Run yarn create react-app my-app --template @sumup, where my-app is the name of your project.

This will create the folder my-app and initialize a new project inside. The project will be based on create-react-app and will use SumUp's Circuit UI component library and Foundry toolkit.

Optional: CRA will use React version ^17.0.0 with the new JSX runtime. You can remove any synthetic default React import statements from the codebase (i.e. import React from 'react'). If you do, make sure you disable the corresponding ESLint rules in .eslintrc.js, by providing overrides to Foundry in a second argument. See the React team's blog post covering the new runtime for details about the ESLint rules.

🛠 Development workflow

Firing up the tools

Run yarn start to start the development build. The app should automatically open in your browser. Changes you make to src/App.js should be visible on the page almost immediately.

To create a production build of your app, run yarn build. react-scripts will create an optimized production build of your application inside the build folder of your project. It will also provide you with additional details on what to do with them.

Adding a new component

We try to make adding new components as easy as possible. Run yarn create:component YourComponentName to launch the plop CLI exposed and configured by Foundry.

Linting your code

A linter is a tool that checks your code for

• problems that will cause it to break when run, or
• code style that violates a given set of rules the project is following.

Linting serves as a first line of defence against evil bugs on production.​ Your project will be set up to use a version of the popular ESLint linter for JavaScript provided by Foundry. You can lint your code and apply automatic fixes by running yarn lint. Usually, your editor is able to integrate with ESLint.

Writing tests

Writing tests is great. Tests are the second line of defence against bugs ending up on production. By covering your application in unit and integration tests, you can be sure you did not break anything when, for example, shipping refactored code to production. Your new React project comes with testing built in. By running yarn test you will start the test runner, Jest. As you add tests or make changes to your code, Jest will re-run tests and show you the results. The app will come with react-testing-library set up for writing UI tests for your React components. Check out src/App.spec.js for examples.

For component tests we export a custom render method for testing-library/react from src/test-utils.js. The custom render method ensures components are wrapped in a ThemeProvider with the Circuit UI theme. Components created with the create:component script will have a *.spec.js file with the local render method imported. The import should look something like this. The Testing Library docs for React contain more details on how to add more React providers for your tests.

import { render } from '../../test-utils';

📖 Useful resources

• The docs for create-react-app contain a lot of solutions for common problems when writing a React application.
• Foundry docs.
• Circuit UI docs and storybook.
• The README for@testing-library/react.

⚠️ Troubleshooting

Debug mode

create-react-app has a debug mode. To output verbose logging to your console, add the --debug flag when creating your app. For example:

yarn create react-app my-debugging-app --debug --template @sumup

Broken build due to ESLint version

Because we depend on create-react-app@latest there is a chance that the shipped ESLint version in react-scripts is different from the one shipped with Foundry. Both projects are toolkits. When the build for your application fails, try to create your app with a version of CRA that ships the same version of ESLint as the Foundry's canary channel.