@exercism/eslint-config-tooling

This is the shared eslint configuration used by various pieces of tooling, such as the JavaScript Analyzer, Representer, and Test Runner. The same configuration is used for the TypeScript tooling as well as various other pieces of technology. Shareable configs are designed to work with the extends feature of .eslintrc files. This means you can use the same configuration Exercism uses in your own projects!

Usage

To use the configuration for students, open your eslint configuration file, and add the following value to extends. For example, for JSON based configuration files:

{
  "extends": "@exercism/eslint-config-tooling"
}

Configuration

Find the configuration here. It's goal is to help detect and prevent common problems, and enforce a consistent code style.

The rules are based on:

• eslint:recommended
• plugin:import
• A few extra rules that catch common issues but are not enabled via the recommended plugin.

It also includes the prettier plugin because we use prettier to achieve consistent code formatting. This plugin turns off rules that conflict with formatting.

Because most of the tooling is primarily focussing on running on Node, only node and es2021 are turned on as environment, but when extending this configuration, you can add more (or turn those off).

Type-based rules

In order to be able to use type information in the eslint rules, the appropiate parser option must be set.

{
  "parserOptions": {
    "tsconfigRootDir": __dirname,
    "project": ["./tsconfig.json"]
  }
}

"tsconfigRootDir": __dirname, is not required, but allows your editor to not infer this value, which it almost always does incorrectly, especially when you do not open the repository at git root / location of the .eslint configuration file. Setting the tsconfigRootDir forces the root directory for eslint to be the value given, and stop the editor and editor plugins from inferring the value. Setting it to a value of __dirname is only available in JavaScript based configuration files.

Setup with multiple tsconfig.json and ts-paths

When working with multiple folders and a composite tsconfig.json structure and/or using the compilerOptions with paths, you might have difficulty resolving issues around it not being able to find files, definitions, and more. A common problem is eslint complaining about files not being present or included in the configuration. Another common problem is types reporting as any to eslint, even when they do resolve inside the editor.

An easy way to resolve this is to create a new tsconfig.eslint.json that includes all the files in the project, including the test files. That tsconfig.eslint.json should then be referred in project, instead of the regular configuration file. You can check out the JavaScript Analyzer for an example.