ESLint VS jest

Let's be honest - setting up tools for a new project can be a frustrating process. Especially when you want to jump straight to coding part. This is often the case with ESLint and Prettier, two popular tools in the JavaScript ecosystem that can sometimes interfere with each other when it comes to code formatting. Fortunately, there's a simple solution to this process, and it's called eslint-plugin-prettier.

Do you have the need to find and fix problems in your JavaScript? Then ESLint is for you. With over 120 million downloads each month, it's definitely one of the most popular projects out there. The latest version introduces a new configuration system, designed to simplify available configuration options. Old and deprecated rules have been removed, and a new configuration inspector has been added. Check out the blog for all the highlights, and a migration guide.

ESLint: A pluggable and configurable linter tool for identifying and reporting on patterns in JavaScript.

Automating code checks with static code analysis allows us to enforce code styling effectively. By integrating tools into our workflow, we can identify errors at an early stage, while coding instead of blocking us at the end. For instance, flake8 checks Python code for style and errors, eslint performs similar checks for JavaScript, and prettier automatically formats code to maintain consistency.

If you're a developer, you're surely familiar with Prettier and ESLint. With over 8 years of existence, they have established themselves as references in the JavaScript ecosystem.

eslint is used to avoid code errors

No lint errors: The committed code does not contain any lint errors (eslint).

Let’s walk through the steps for a one-time setup to configure husky pre-commit and pre-push hooks, ESLint with code styles conventions, prettier code formatter, and lint-staged. Husky automatically runs a script on each commit or push. This is useful for linting files to enforce code styles that keeps the entire code base following conventions.

GitHub | Website

ESLint: A pluggable and configurable linter tool for identifying and reporting on patterns in JavaScript.

There are several testing approaches you can take to ascertain the functionality of the auth API. One way would be to automate the testing using unit tests with tools like Jest and Supertest. Alternatively, you can make use of API clients like Postman or the Thunder Client VS Code extension to test the API.

GitHub | Website

Jest

you have selected a testing framework. In my case, it's Jest with Supertest

Jest, created and maintained by Facebook, is a JavaScript testing framework with a focus on simplicity. It is often recognized for its zero-configuration setup and seamless integration, especially with React applications, making it a favored choice for developers in both small-scale projects and large enterprise applications.

Jest (https://jestjs.io/)

console.error Jest encountered an unexpected token Jest failed to parse a file. This happens e.g. when your code or its dependencies use non-standard JavaScript syntax, or when Jest is not configured to support such syntax. Out of the box Jest supports Babel, which will be used to transform your files into valid JS based on your Babel configuration. By default "node\_modules" folder is ignored by transformers. Here's what you can do: • If you are trying to use ECMAScript Modules, see https://jestjs.io/docs/ecmascript-modules for how to enable it. • If you are trying to use TypeScript, see https://jestjs.io/docs/getting-started#using-typescript • To have some of your "node\_modules" files transformed, you can specify a custom "transformIgnorePatterns" in your config. • If you need a custom transformation specify a "transform" option in your config. • If you simply want to mock your non-JS modules (e.g. binary assets) you can stub them out with the "moduleNameMapper" config option. You'll find more details and examples of these config options in the docs: https://jestjs.io/docs/configuration For information about custom transformations, see: https://jestjs.io/docs/code-transformation

Note: I will be using Jest as testing framework throughout the examples.

We use Jest Framework for testing. Jest is not a dogma, and, of course, in its place can be any other test runner, such as Mocha or Ava. Let's focus on tests. I'll provide a short example because I don’t want to waste your time. You can find the full version here. It's crucial to read the comments in the code below. Let's go!

Jest has long been my favorite got to test runner when it comes to UI unit and integration testing. With tools like React Testing Library (Testing Library framework for React) you get the benefit of very easy to write and maintain tests, as well as a quick and efficient way to run our tests.